2648:. To achieve densification at lower temperatures, several techniques can be employed: additives such as SiC can be used in order to form a liquid phase at the sintering temperature, the surface oxide layer can be removed, or the defect concentration can be increased. SiC can react with the surface oxide layer in order to provide diboride surfaces with higher energy: adding 5–30 vol% SiC has demonstrated improved densification and oxidation resistance of UHTCs. SiC can be added as a powder or a polymer to diboride UHTCs. The addition of SiC as a polymer has several advantages over the more traditional addition of SiC as a powder because SiC forms along the grain boundaries when added as a polymer, which increases measures of fracture toughness (by ~24%). In addition to improved mechanical properties, less SiC needs to be added when using this method, which limits the pathways for oxygen to diffuse into the material and react. Although addition of additives such as SiC can improve densification of UHTC materials, these additives lower the maximum temperature at which UHTCs can operate due to the formation of
2880:
for use in space nuclear power applications. While boron carbide is the most popular material for fast breeder reactors due to its lack of expense, extreme hardness comparable to diamond, and high cross-section, it completely disintegrates after a 5% burnup and is reactive when in contact with refractory metals. Hafnium diboride also suffers from high susceptibility to material degradation with boron transmutation, but its high melting point of 3,380 °C and the large thermal neutron capture cross section of hafnium of 113
1614:
materials. However, the different methods of processing UHTCs can lead to great variation in hardness values. UHTCs exhibit high flexural strengths of > 200 MPa at 1,800 °C, and UHTCs with fine-grained particles exhibit higher flexural strengths than UHTCs with coarse grains. It has been shown that diboride ceramics synthesized as a composite with silicon carbide (SiC) exhibit increased fracture toughness (increase of 20% to 4.33 MPam) relative to the pure diborides. This is due to material
290:
2196:(SHS). This technique takes advantage of the high exothermic energy of the reaction to cause high temperature, fast combustion reactions. Advantages of SHS include higher purity of ceramic products, increased sinterability, and shorter processing times. However, the extremely rapid heating rates can result in incomplete reactions between Zr and B, the formation of stable oxides of Zr, and the retention of
77:
411:
them on modified nuclear ordnance Mk12A reentry vehicles and launching them on
Minuteman III ICBMs. Sharp B-1 had a HfB2/SiC nosecone with a tip radius of 3.5 mm which experienced temperatures well above 2,815 °C during reentry, ablating away at an airspeed of 6.9 km/s as predicted; however, it was not recovered and its axially-symmetric cone shape did not provide
36:
2787:/20 vol%SiC can be prepared with 99% density at 2,000 °C in 5 min via spark plasma sintering. ZrB2-SiC composites have also been prepared by spark plasma sintering at 1,400 °C over a period of 9 min. Spark plasma sintering has proven to be a useful technique for the synthesis of UHTCs, especially for preparation of UHTCs with smaller grain sizes.
136:
2831:, and stoichiometric boron content. Boron acts as a "burnable" neutron absorber because its two isotopes, 10B and 11B, both transmute into stable nuclear reaction products upon neutron absorption (4He + 7Li and 12C, respectively) and therefore act as sacrificial materials which protect other components which become more
2766:/20 vol.% SiC by 25%. Sintered density has also been shown to increase with the addition of Fe (up to 10% w/w) and Ni (up to 50% w/w) to achieve densifications of up to 88% at 1,600 °C. More advances in pressureless sintering must be made before it can be considered a viable method for UHTC processing.
2668:
of UHTC pellets obtained from this method. In order to achieve >99% densification from hot pressing, temperatures of 1,800–2,000 °C and pressures of 30 MPa or greater are required. UHTC materials with 20 vol.% SiC and toughened with 5% carbon black as additives exhibit increased densification
1643:
A significant enhancement in hardness (~30%) of (Hf-Ta-Zr-Nb)C material compared to the monolithic UHTCs (HfC, TaC, ZrC, NbC) and in comparison to the hardest monocarbide (HfC) and the binary (Hf-Ta)C was recorded. The mechanism behind this enhancement in hardness maybe because of bonding behavior or
1242:
and HfN have similarly strong covalent bonds but their refractory nature makes them especially difficult to synthesize and process. The stoichiometric nitrogen content can be varied in these complexes based on the synthetic technique utilized; different nitrogen content will give different properties
2879:
Due to the combination of refractory properties, high thermal conductivity, and the advantages of large stoichiometric boron content outlined in the above discussion of integral neutron absorbing fuel pellet cladding, refractory diborides have been used as control rod materials and have been studied
2778:
is suppressed by rapid heating over the range 1,500–1,900 °C; this minimizes the time the material has to coarsen. Higher densities, cleaner grain boundaries, and elimination of surface impurities can all be achieved with spark plasma sintering. Spark plasma sintering also uses a pulsed current
2663:
Hot pressing is a popular method for obtaining densified UHTC materials that relies upon both high temperatures and pressures to produce densified materials. Powder compacts are heated externally and pressure is applied hydraulitically. In order to improve densification during hot pressing, diboride
2753:
by pressureless sintering is very difficult to obtain; Chamberlain et al. have only been able to obtain ~98% densification by heating at 2,150 °C for 9 h (Figure 3). Efforts to control grain size and improve densification have focused on adding third phases to the UHTCs, some examples of these
1624:
The UHTC composites show higher mechanical properties like
Tensile strength, Young's modulus, hardness, flexural strength, and fracture toughness at high temperatures as compared to monolithic UHTCs. The high sintering temperature and pressure result in high residual stress in the composites, which
2398:
with B. At temperatures higher than 1600 °C, pure diborides can be obtained from this method. Due to the loss of some boron as boron oxide, excess boron is needed during borothermic reduction. Mechanical milling can lower the reaction temperature required during borothermic reduction. This is
2795:
UHTCs, specifically Hf and Zr based diboride, are being developed to handle the forces and temperatures experienced by leading vehicle edges in atmospheric reentry and sustained hypersonic flight. The surfaces of hypersonic vehicles experience extreme temperatures in excess of 2,500 °C while
1632:
The Young's modulus for TiC-WC (3.5 wt%) - CNT(2 wt%) at 1,600 °C is 428 GPa vs 300 GPa for TiC and the flexural toughness of TiC-WC (3.5 wt%) - CNT (2 wt%) at the same temperature is 8.1 MPa m as compared to TiC which is 3.7 MPa m. For ZrC the fracture toughness at 1,900 °C is 4 MPa m
415:
data needed to evaluate the performance of UHTCs in linear leading edges. To improve the characterization of UHTC mechanical strength and better study their performance, SHARP-B2, was recovered and included four retractable, sharp wedge-like protrusions called "strakes" which each contained three
410:
In order to test real world performance of UHTC materials in reentry environments, NASA Ames conducted two flight experiments in 1997 and 2000. The slender
Hypersonic Aero-thermodynamic Research Probes (SHARP B1 and B2) briefly exposed the UHTC materials to actual reentry environments by mounting
2773:
is another method for the processing of UHTC materials. Spark plasma sintering often relies on slightly lower temperatures and significantly reduced processing times compared to hot pressing. During spark plasma sintering, a pulsed direct current passes through graphite punch rods and dies with
2896:
has been used as a drained cathode in the electroreduction of molten Al(III). In drained-cathode processes, aluminum can be produced with an electrode gap of only 0.25 m with an accompanying reduction in required voltage. However, implementation of such technology still faces hurdles: with a
1613:
Table 3 lists UHTC carbides and borides mechanical properties. It is extremely important that UHTCs are able to retain high bending strength and hardness at high temperatures (above 2000 °C). UHTCs generally exhibit hardness above 20 GPa due to the strong covalent bonds present in these
466:, though significant work has continued in characterizing the nitrides, oxides, and carbides of the group four and five elements. In comparison to carbides and nitrides, the diborides tend to have higher thermal conductivity but lower melting points, a tradeoff which gives them good thermal
1628:
At 1,200 °C, the flexural strength of SiC is 170 MPa vs SiC-ZrC (10 wt%) is 350 MPa. At 2,000 °C, Titanium
Carbide's flexural strength is 410 MPa vs TiC-WC (5% vol) is 491 MPa vs TiC-SiC (40% vol) is 543 MPa. Similarly the flexural strength for TaC-SiC (20% vol) is 715 MPa at
1553:
resulting from bonding between boron 2p orbitals and metal d orbitals; before group (IV), the number of available electrons in a unit cell is insufficient to fill all bonding orbitals, and beyond it they begin to fill the antibonding orbitals. Both effects reduce the overall
2891:
Titanium diboride is a popular material for handling molten aluminum due to its electrical conductivity, refractory properties, and its ability to wet with molten aluminum providing a superior electrical interface while not contaminating the aluminum with boron or titanium.
2863:
at the end of a fuel cycle. In addition to this deleterious effect of integrating a neutron absorber on the surface of a fuel pellet, boron coatings have the effect of creating a power density bulge in the middle of a nuclear reactor fuel cycle through the superposition of
2664:
powders can undergo milling by attrition to obtain powders of <2μm. Milling also allows for more uniform dispersion of the additive SiC. Hot pressing temperature, pressure, heating rate, reaction atmosphere, and holding times are all factors that affect the density and
2643:
is only achieved at temperatures above 1800 °C once grain boundary diffusion mechanisms become active. Unfortunately, processing of UHTCs at these temperatures results in materials with larger grain sizes and poor mechanical properties including reduced toughness and
2796:
also being exposed to high-temperature, high-flow-rate oxidizing plasma. The material design challenges associated with developing such surfaces have so far limited the design of orbital re-entry bodies and hypersonic air-breathing vehicles such as scramjets and DARPA's
2733:
can lower densification temperatures and can react with surface oxides to promote densification. Hot pressing may result in improved densities for UHTCs, but it is an expensive technique that relies on high temperatures and pressures to provide useful materials.
2200:. Stoichiometric reactions have also been carried out by reaction of attrition milled (wearing materials by grinding) Zr and B powder (and then hot pressing at 600 °C for 6 h), and nanoscale particles have been obtained by reacting attrition milled Zr and B
2638:
Diboride-based UHTCs often require high-temperature and -pressure processing to produce dense, durable materials. The high melting points and strong covalent interactions present in UHTCs make it difficult to achieve uniform densification in these materials.
2803:
Sharp edges dramatically reduce drag, but the current generation of thermal protection system materials are unable to withstand the considerably higher forces and temperatures experienced by sharp leading edges in reentry conditions. The relation between
1515:
In comparison with carbide and nitride-based ceramics, diboride-based UHTCs exhibit higher thermal conductivity (refer to Table 2, where we can see that hafnium diboride has thermal conductivity of 105, 75, 70 W/m*K at different temperature while
2816:, enhancing the fuel efficiency of sustained flight vehicles such as DARPA's HTV-3 and the landing cross-range and operational flexibility of reusable orbital spaceplane concepts being developed such as the Reaction Engines Skylon and Boeing X-33.
382:
2937:
single crystals to 212.96 MPa, with flexural strength highly correlated to the size of grains in the annealed ceramic material. Conductivity at 500 °C was found to be 0.005 Ω cm for the 40% SiC composite, versus 0.16 Ω cm in pure SiC.
1647:
For applications based on combustion harsh environments and aerospace, Monolithic UHTCs are of concern because of their low fracture toughness and brittle behavior. UHTC composites are a potential approach to overcome these deficiencies.
2523:
UHTCs can be prepared from solution-based synthesis methods as well, although few substantial studies have been conducted. Solution-based methods allow for low temperature synthesis of ultrafine UHTC powders. Yan et al. have synthesized
3908:
Fattahi, M.; Asl, M.S.; Delbari, S.A.; Namini, A.S.; Ahmadi, Z.; Mohammadi, M. Role of nano-WC addition on microstructural, mechanical and thermal characteristics of TiC-SiCw composites. Int. J. Refract. Met. Hard Mater. 2020, 90,
2928:
allows for its conductivity to decrease with increasing temperature, preventing uncontrollable electrical discharge while maintaining high operational upper bounds for operation. It was also found that through incorporation of 40%
2897:
reduction in voltage, there is a concomitant reduction in heat generation and better insulation at the top of the reactor is required. In addition to improved insulation, the technology requires better bonding methods between TiB
2740:
is another method for processing and densifying UHTCs. Pressureless sintering involves heating powdered materials in a mold in order to promote atomic diffusion and create a solid material. Compacts are prepared by uniaxial die
2858:
fuel pellets in
Westinghouse AP-1000 nuclear reactors. The high thermal neutron absorbance of boron also has the secondary effect of biasing the neutron spectrum to higher energies, so the fuel pellet retains more radioactive
2561:
soon follows. The polymer must be stable, processable, and contain boron and carbon in order to be useful for the reaction. Dinitrile polymers formed from the condensation of dinitrile with decaborane satisfy these criteria.
2207:(10 nm in size). Unfortunately, all of the stoichiometric reaction methods for synthesizing UHTCs employ expensive charge materials, and therefore these methods are not useful for large-scale or industrial applications.
378:, with research at the center continuing to the present through funding from the NASA Fundamental Aeronautics Program. UHTCs also saw expanded use in varied environments, from nuclear engineering to aluminum production.
4781:
Guron, Marta M., Myung Jong Kim, and Larry G. Sneddon. (2008). "A Simple
Polymeric Precursor Strategy for the Syntheses of Complex Zirconium and Hafnium‐Based Ultra High‐Temperature Silicon‐Carbide Composite Ceramics".
2378:
phases have been formed using a plasma voltage and current of 50 V and 500 A, respectively. These coating materials exhibit uniform distribution of fine particles and porous microstructures, which increased hydrogen
474:
of many UHTCs are shown in Table 1. Despite the high melting points of pure UHTCs, they are unsuitable for many refractory applications because of their high susceptibility to oxidation at elevated temperatures.
1532:
sufficient for the failure of SiC; indeed, it was found that hollow cylinders could not be cracked by an applied radial thermal gradient without first being notched on the inner surface. UHTCs generally exhibit
2602:(PECVD) has also been used to prepare UHTC diborides. After plasma of the reacting gases is created (by radio frequency or direct current discharge between two electrodes) the reaction takes place, followed by
2139:
are greatly enhanced through the inclusion of 30% weight silicon carbide due to the formation of a protective glassy surface layer upon the application of temperatures in excess of 1,000 °C composed of
2144:. To determine the effect of SiC content on diboride oxidation, ManLabs conducted a series of furnace oxidation experiments, in which the oxidation scale thickness as a function of temperature for pure HfB
2552:
can be dispersed in boron carbide polymeric precursors prior to reaction. Heating the reaction mixture to 1,500 °C results in the in situ generation of boron carbide and carbon, and the reduction of
4152:
Liu, Han et al. "Microstructure and mechanical properties of the spark plasma sintered TaC/SiC composites: Effects of sintering temperatures". Journal of The
European Ceramic Society 32 (2012): 3617-3625
446:
on the rear strakes was much higher than expected. The material failures were found to result from very large grain sizes in the composites and pure ceramics, with cracks following macroscopic crystal
2544:
at 1,500 °C. The synthesized powders exhibit 200 nm crystallite size and low oxygen content (~ 1.0 wt%). UHTC preparation from polymeric precursors has also been recently investigated. ZrO
2695:-SiC composites at 1800 °C. These additives react with impurities to form a transient liquid phase and promote sintering of the diboride composites. The addition of rare earth oxides such as Y
1267:(5–7.8 x 10 K) and improved oxidation resistance in comparison to other classes of UHTCs. Thermal expansion, thermal conductivity and other data are shown in Table 2. The crystal structures,
1562:
and therefore the enthalpy of formation and melting point. Experimental evidence shows that as one moves across the transition metal series in a given period, the enthalpy of formation of MB
4825:
Zhou, Shanbao; et al. (2010). "Microstructure, mechanical properties and thermal shock resistance of zirconium diboride containing silicon carbide ceramic toughened by carbon black".
2800:
because the bow shock in front of a blunt body protects the underlying surface from the full thermal force of the onrushing plasma with a thick layer of relatively dense and cool plasma.
2286:
mixture yields increased conversion to the diboride, and particle sizes of 25–40 nm at 800 °C. After metallothermic reduction and DSHS reactions, MgO can be separated from ZrB
386:
389:
388:
384:
383:
4095:
Ni, Dewei; Cheng, Yuan; Zhang, Jiaping; Liu, Ji-Xuan; Zou, Ji; Chen, Bowen; Wu, Haoyang; Li, Hejun; Dong, Shaoming; Han, Jiecai; Zhang, Xinghong; Fu, Qiangang; Zhang, Guo-Jun (2022).
390:
2669:
above 1,500 °C, but these materials still require temperatures of 1,900 °C and a pressure of 30 MPa in order to obtain near theoretical densities. Other additives such as
430:
as shown in Figure 1. The vehicle was successfully recovered, despite the fact that it impacted the sea at three times the predicted velocity. The four rear strake segments (HfB
3438:
Cedillos-Barraza, Omar; Manara, Dario; Boboridis, K.; Watkins, Tyson; Grasso, Salvatore; Jayaseelan, Daniel D.; Konings, Rudy J. M.; Reece, Michael J.; Lee, William E. (2016).
3027:
Lawson, John W., Murray S. Daw, and
Charles W. Bauschlicher (2011). "Lattice thermal conductivity of ultra high temperature ceramics ZrB2 and HfB2 from atomistic simulations".
2160:/20% SiC has the best oxidation resistance. Extreme heat treatment leads to greater oxidation resistance as well as improved mechanical properties such as fracture resistance.
2749:
that hinders densification occurs during sintering due to the low-intrinsic sinterability and the strong covalent bonds of Ti, Zr, and Hf diborides. Full densification of ZrB
1566:
ceramics increases and peaks at Ti, Zr, and Hf before decaying as the metal gets heavier. As a result, the enthalpies of formation of several important UHTCs are as follows:
154:
2606:. The deposition takes place at lower temperatures compared to traditional CVD because only the plasma needs to be heated to provide sufficient energy for the reaction. ZrB
218:
and are highly resistant to thermal shock, meaning they can withstand sudden and extreme changes in temperature without cracking or breaking. Chemically, they are usually
289:
2363:
and better sinterability. Boron carbide must be subjected to grinding prior to the boron carbide reduction in order to promote oxide reduction and diffusion processes.
4992:
4945:
4811:
4633:
4335:
3822:
3745:
3613:
3424:
3370:
3082:
2218:
to their respective diborides can also be achieved via metallothermic reduction. Inexpensive precursor materials are used and reacted according to the reaction below:
2370:
if a UHTC coating is desired. Precursor or powder particles react with plasma at high temperatures (6,000–15,000 °C) which greatly reduces the reaction time. ZrB
4085:
Vinci A, Zoli L, Sciti D, et al. Mechanical behaviour of carbon fibre reinforced TaC/SiC and ZrC/SiC composites up to 2100 °C. J Eur Ceram Soc 2019, 39: 780–787
3838:
2267:
via SHS often leads to incomplete conversion of reactants, and therefore double SHS (DSHS) has been employed by some researchers. A second SHS reaction with Mg and
387:
49:
2783:
that cleans surface oxides off of the powder. This enhances grain boundary diffusion and migration as well as densification of the material. The UHTC composite ZrB
1243:
to the material, such as how if x exceeds 1.2 in ZrNx, a new optically transparent and electrically insulating phase appears to form. Ceramic borides such as HfB
4474:
Zoli, Luca; Costa, Anna Luisa; Sciti, Diletta (December 2015). "Synthesis of nanosized zirconium diboride powder via oxide-borohydride solid-state reaction".
4244:
Tului, Mario; et al. (2008). "Effects of heat treatments on oxidation resistance and mechanical properties of ultra high temperature ceramic coatings".
3662:
Fahrenholtz, W. G.; et al. (2004). "Processing and characterization of ZrB 2-based ultra-high temperature monolithic and fibrous monolithic ceramics".
2193:
2920:/60%SiC composites have been used as novel conducting ceramic heaters which display high oxidation resistance and melting points, and do not display the
2599:
1640:
The high strength of the materials is obtained due to the high homogeneities of the microstructures and the solute dispersion in the microstructures.
458:
Most research conducted in the last two decades has focused on improving the performance of the two most promising compounds developed by
Manlabs, ZrB
4138:
Min-Haga, Eungi and
William D. Scott. "Sintering and mechanical properties of ZrC-ZrO2 composites". Journal of Materials Science 23 (1988): 2865-2870
1549:
structures with alternating hexagonal sheets of metal and boride atoms. In such structures, the principal frontier electronic states are bonding and
5198:
5143:
5090:
3875:
3873:
K. Sairam; J.K. Sonber; T.S.R.Ch. Murthy; C. Subramanian; R.K. Fotedar; R.C. Hubli. (2014). "Reaction spark plasma sintering of niobium diboride".
5057:
4918:
4860:
4784:
4536:
4308:
4279:
3275:
2909:
capital cost of the former and the design difficulty of the latter. Composite materials must have each component degrade at the same rate, or the
4161:
Stanley R. Levine and Elizabeth J. OpilaGlenn Research Center, Cleveland, Ohio. Characterization of an Ultra-High Temperature Ceramic Composite.
1274:
Table 2. Thermal expansion coefficients across selected temperature ranges and thermal conductivity at a fixed temperature for selected UHTCs.
4534:
Yan, Yongjie; et al. (2006). "New Route to Synthesize Ultra‐Fine Zirconium Diboride Powders Using Inorganic–Organic Hybrid Precursors".
4355:
3768:
2990:
385:
374:
such as the National Aerospace Plane, Venturestar/X-33, Boeing X-37, and the Air Force's Blackstar program. New research in UHTCs was led by
5055:
Venkateswaran, T.; et al. (2006). "Densification and properties of transition metal borides-based cermets via spark plasma sintering".
4684:
Reich, Silvia; et al. (1992). "Deposition of thin films of Zirconium and Hafnium Boride by plasma enhanced chemical vapor deposition".
3534:
Barraud, Elodie; et al. (2008). "Mechanically activated solid-state synthesis of hafnium carbide and hafnium nitride nanoparticles".
3254:
Bargeron, C. B.; et al. (1993). "Oxidation Mechanisms of Hafnium Carbide and Hafnium Diboride in the Temperature Range 1400 to 21C".
4392:
Karuna Purnapu Rupa, P.; et al. (2010). "Microstructure and Phase Composition of Composite Coatings Formed by Plasma Spraying of ZrO
419:
The SHARP-B2 test that followed permitted recovery of four segmented strakes which had three sections, each consisting of a different HfB
5345:
5158:
Sironen, Charlton (2012). "Neutronic characteristics of using zirconium diboride and gadolinium in a Westinghouse 17x17 fuel assembly".
4402:
55:
2854:
creates a gap between coating and fuel, and increases the fuel's centerline temperature; such cladding materials have been used on the
2805:
4026:"High-temperature Mechanical Properties and Their Influence Mechanisms of ZRC-Modified C-SiC Ceramic Matrix Composites up to 1600 °C"
450:. Since this test, NASA Ames has continued refining production techniques for UHTC synthesis and performing basic research on UHTCs.
317:
properties of binary ceramics, they discovered that the early transition metal borides, carbides, and nitrides had surprisingly high
4447:
1234:
carbides have high melting points due to covalent carbon networks although carbon vacancies often exist in these materials; indeed,
190:
172:
117:
63:
301:
Materials Laboratory to begin funding the development of a new class of materials that could withstand the environment of proposed
5141:
Xu, Liang; et al. (2012). "Study on in-situ synthesis of ZrB2 whiskers in ZrB2 ZrC matrix powder for ceramic cutting tools".
3764:"Ultrahigh temperature ceramics (UHTCs) based on ZrB2 and HfB2 systems: Powder synthesis, densification and mechanical properties"
2986:"Ultrahigh temperature ceramics (UHTCs) based on ZrB2 and HfB2 systems: Powder synthesis, densification and mechanical properties"
2188:
via stoichiometric reaction is thermodynamically favorable (ΔG=−279.6 kJ mol) and therefore, this route can be used to produce ZrB
2921:
3805:
Rhodes, W. H., Clougherty, E. V. and Kalish, D. (1970). "Research and Development of Refractory Oxidation Resistant Diborides".
3730:
Rhodes, W. H., Clougherty, E. V. and Kalish, D. (1968). "Research and Development of Refractory Oxidation Resistant Diborides".
4889:
4827:
4766:
Kaufman, Larry & Edward V. Clougherty. (1963). "Investigation of Boride Compounds for Very High-Temperature Applications".
3536:
3168:
2797:
87:
4916:
Chamberlain, Adam L., William G. Fahrenholtz, and Gregory E. Hilmas. (2005). "Pressureless sintering of zirconium diboride".
3393:
2913:
and thermal conductivity of the surface will be lost with active material still remaining deeper within the electrode plate.
4306:
Chamberlain, Adam L., William G. Fahrenholtz, and Gregory E. Hilmas. (2009). "Reactive hot pressing of zirconium diboride".
2240:
Mg is used as a reactant in order to allow for acid leaching of unwanted oxide products. Stoichiometric excesses of Mg and B
5257:
Cheminant-Coatanlem, P.; et al. (1998). "Microstructure and nanohardness of hafnium diboride after ion irradiations".
4225:
2411:
and B after milling. This method is also not very useful for industrial applications due to the loss of expensive boron as
5118:
4887:
Zhang, Xinghong; et al. (2008). "Effects of Y2O3 on microstructure and mechanical properties of ZrB2- SiC ceramics".
1534:
371:
302:
2955:
Wuchina, E.; et al. (2007). "UHTCs: ultra-high temperature ceramic materials for extreme environment applications".
5390:
5380:
5259:
3664:
3227:
442:/SiC/C) failed. The actual heat flux was 60% less than expected, actual temperatures were much lower than expected, and
4176:"Introduction to H2020 project C3HARME – next generation ceramic composites for combustion harsh environment and space"
2100:, which is rapidly lost at the elevated temperatures UHTCs are most useful at; boron, for example, readily oxidizes to
214:
that can withstand extremely high temperatures without degrading, often above 2,000 °C. They also often have high
4445:
Peshev, P. & G. Bliznakov. (1968). "On the borothermic preparation of titanium, zirconium and hafnium diborides".
3986:
Mao, Haobo; Shen, Fuqiang; Zhang, Yingyi; Wang, Jie; Cui, Kunkun; Wang, Hong; Lv, Tao; Fu, Tao; Tan, Tianbiao (2021).
2568:(CVD) of titanium and zirconium diborides is another method for preparing coatings of UHTCs. These techniques rely on
1625:
can be released at high temperatures. Therefore, the mechanical properties increase with the increase in temperature.
4246:
3225:
Shimada, Shiro. (2002). "A thermoanalytical study on the oxidation of ZrC and HfC powders with formation of carbon".
4959:
Wang, Xin-Gang, Wei-Ming Guo, and Guo-Jun Zhang. (2009). "Pressureless sintering mechanism and microstructure of ZrB
3988:"Microstructure and Mechanical Properties of Carbide Reinforced TiC-Based Ultra-High Temperature Ceramics: A Review"
5385:
3029:
2876:
cermets are being studied which would extend fuel lifetime by superimposing three simultaneous degradation curves.
2808:
and temperature in a leading edge is inversely proportional, i.e. as radius decreases temperature increases during
297:
Beginning in the early 1960s, demand for high-temperature materials by the nascent aerospace industry prompted the
5012:
4723:
2088:
While UHTCs have desirable thermal and mechanical properties, they are susceptible to oxidation at their elevated
281:. However, ongoing research is focused on improving the processing techniques and mechanical properties of UHTCs.
5341:"The Development of an Electroconductive SiC-ZrB Composite through Spark Plasma Sintering under Argon Atmosphere"
2565:
375:
270:
242:
3317:
Jenkins, R.; et al. (1988). "Powder Diffraction File: from the International Center for Diffraction Data".
3273:
Levine, Stanley R.; et al. (2002). "Evaluation of ultra-high temperature ceramics for aeropropulsion use".
2746:
2301:
reduction is one of the most popular methods for UHTC synthesis. The precursor materials for this reaction (ZrO
366:
spaceplane development. Three decades later, however, research interest was rekindled by a string of 1990s era
358:
UHTC research was largely abandoned after the pioneering mid-century Manlabs work due to the completion of the
3214:. 2nd Annual Conference on Composites, Materials and Structures, Cocoa Beach, FL, United States. Vol. 22.
2351:
has also been observed as a product from the reaction, but if the reaction is carried out with 20–25% excess B
2184:. This reaction provides for precise stoichiometric control of the materials. At 2,000 K, the formation of ZrB
1218:
are brittle due to the strong bonds that exist between carbon atoms. The largest class of carbides, including
4647:
Pierson, J. F.; et al. (2000). "Low temperature ZrB2 remote plasma enhanced chemical vapor deposition".
4162:
298:
5173:
Sinclair, John (1974). "Compatibility of Refractory Materials for Nuclear Reactor Poison Control Systems".
4503:"Synthesis of group IV and V metal diboride nanocrystals via borothermal reduction with sodium borohydride"
3807:
5126:
4565:
2737:
2603:
2594:
for coating on metal (and other material) surfaces. Mojima et al. have used CVD to prepare coatings of ZrB
2573:
1252:
266:
5006:
Khanra, A. K. & M. M. Godkhindi. (2005). "Effect of Ni additives on pressureless sintering of SHS ZrB
3353:
Schwetz, K. A., Reinmoth, K. and Lipp (1981). "A. Production and Industrial Uses of Refractory Borides".
2905:
or applying composite coatings each present their own unique challenges, with the high cost and large TiB
2347:
This method requires a slight excess of boron, as some boron is oxidized during boron carbide reduction.
2111:
which becomes a liquid at 490 °C and vaporizes very rapidly above 1,100 °C; in addition, their
5230:
4986:
4939:
4805:
4627:
4329:
3816:
3739:
3607:
3418:
3364:
3326:
3076:
2615:
2610:
has been prepared via PECVD at temperatures lower than 600 °C as a coating on zircalloy. Zirconium
2291:
2201:
2089:
306:
2819:
Zirconium diboride is used in many boiling water reactor fuel assemblies due to its refractory nature,
3440:"Investigating the highest melting temperature materials: A laser melting study of the TaC-HFC system"
95:
5305:
5268:
5021:
4732:
4721:
Sonber, J. K. & A. K. Suri. (2011). "Synthesis and consolidation of zirconium diboride: review".
4695:
4658:
4607:
4411:
4364:
4187:
4037:
3935:
3847:
3777:
3712:
3673:
3451:
3409:
Pankratz, L. B., Stuve, J. M. and Gokcen, N. A. (1984). "Thermodynamic Data for Mineral Technology".
3355:
3137:
3110:
3038:
2999:
2820:
2780:
2723:
2124:
1550:
1211:
676:
521:
318:
215:
5225:
Ewing, Robert A. & Duane Neuman Sunderman. (1961). "Effects of Radiation Upon Hafnium Diboride".
4596:
coated on copper plate by chemical vapour deposition, and its corrosion and oxidation stabilities".
2844:
1621:
Table. 3 Flexural strength, hardness, and Young's Modulus at given temperatures for selected UHTCs.
3199:. 16th AIAA/DLR/DGLR International Space Planes and Hypersonic Systems and Technologies Conference.
3164:"Overview of United States space propulsion technology and associated space transportation systems"
3133:
2957:
2152:
20 v% SiC were compared. At temperatures greater than 2,100 K the oxide scale thickness on pure HfB
326:
1263:. Borides exhibit high thermal conductivity (on the order of 75–105 W/mK) and low coefficients of
5321:
5037:
4965:
4748:
4686:
4427:
4205:
4118:
3689:
3644:
3064:
2824:
2813:
2681:
1581:
1251:
benefit from very strong bonding between boron atoms as well as strong metal to boron bonds; the
427:
348:
334:
250:
211:
1255:
structure with alternating two-dimensional boron and metal sheets give these materials high but
293:
Figure 1. An UHTC strake composed of three different sections with different UHTC compositions.
17:
4065:
3961:
3516:
3477:
3389:
2809:
2580:
2348:
2261:
2169:
1268:
1264:
1239:
1032:
936:
645:
416:
different UHTC compositions which were extended into the reentry flow at different altitudes.
412:
254:
4854:
Zhu, Tao; et al. (2009). "Densification, microstructure and mechanical properties of ZrB
4174:
Sciti, Diletta; Silvestroni, Laura; Monteverde, Frédéric; Vinci, Antonio; Zoli, Luca (2018).
5354:
5313:
5276:
5207:
5099:
5066:
5029:
4974:
4927:
4898:
4869:
4836:
4793:
4740:
4703:
4666:
4649:
4615:
4598:
4574:
4545:
4514:
4483:
4456:
4419:
4372:
4317:
4288:
4255:
4195:
4108:
4055:
4045:
3999:
3951:
3943:
3884:
3855:
3785:
3681:
3636:
3595:
3584:"Mechanical, Thermal and Oxidation Properties of Refractory Hafnium and Zirconium Compounds"
3545:
3508:
3467:
3459:
3284:
3236:
3177:
3054:
3046:
3007:
2966:
2836:
2380:
1595:
1567:
1555:
1529:
1190:
1166:
1066:
1022:
998:
905:
840:
809:
741:
583:
467:
395:
341:
235:
27:
Type of refractory ceramics that can withstand extremely high temperatures without degrading
5243:
3339:
2742:
2712:
2670:
2367:
2120:
1517:
1260:
1235:
1128:
1097:
967:
871:
775:
614:
552:
258:
5084:
Zhao, Yuan; et al. (2009). "Effect of holding time and pressure on properties of ZrB
4377:
4350:
3790:
3763:
3685:
3012:
2985:
2329:
is prepared at greater than 1,600 °C for at least 1 hour by the following reaction:
2248:
are often required during metallothermic reductions in order to consume all available ZrO
2176:
can be synthesized by stoichiometric reaction between constituent elements, in this case
5309:
5272:
5025:
4736:
4699:
4662:
4611:
4415:
4368:
4191:
4041:
3939:
3851:
3781:
3716:
3677:
3455:
3141:
3114:
3042:
3003:
2359:
remains. Lower synthesis temperatures (~1,600 °C) produce UHTCs that exhibit finer
5070:
4873:
4321:
4292:
4060:
4025:
3956:
3923:
3472:
3439:
3318:
2665:
2587:
2541:
2400:
2322:
2101:
707:
447:
5280:
4840:
4670:
4563:
Su, Kai & Larry G. Sneddon. (1993). "A polymer precursor route to metal borides".
4024:
Sha, Jianjun; Wang, Shouhao; Dai, Jixiang; Zu, Yufei; Li, Wenqiang; Sha, Ruyi (2020).
3922:
Castle, Elinor; Csanádi, Tamás; Grasso, Salvatore; Dusza, Ján; Reece, Michael (2018).
3599:
3582:
Opeka, M. M., Talmy, I. G., Wuchina, E. J., Zaykoski, J. A. and Causey, S. J. (1999).
3288:
3240:
5374:
5325:
5296:
5041:
4978:
4931:
4797:
4752:
4619:
4549:
4487:
4460:
4431:
4209:
4122:
3693:
3648:
3068:
2860:
2855:
2745:, and then the compacts are fired at chosen temperatures in a controlled atmosphere.
2640:
2404:
2314:
2298:
1615:
1207:
471:
359:
310:
5088:-SiC composite fabricated by the spark plasma sintering reactive synthesis method".
1629:
1,900 °C which is about 40% higher than TaC (500 MPa) at the same temperature.
4744:
4501:
Zoli, Luca; Galizia, Pietro; Silvestroni, Laura; Sciti, Diletta (23 January 2018).
4259:
3568:
2843:
must be enriched in 11B because the gaseous helium evolved by 10B strains the fuel
2775:
2569:
262:
5119:"Ultra High Temperature Ceramics: Densification, Properties and Thermal Stability"
4902:
4200:
4175:
3549:
2172:
and thus can be prepared by a wide variety of synthetic methods. UHTCs such as ZrB
2123:, the incorporation of fibers, and the addition of rare-earth hexaborides such as
1545:
UHTCs results from the occupancy of bonding and antibonding levels in hexagonal MB
1528:
was investigated by ManLabs and it was found that these materials did not fail at
5211:
5103:
3888:
2115:
makes them poor engineering materials. Current research targets increasing their
2910:
2865:
2832:
2828:
2611:
2412:
2204:
2112:
1256:
403:
399:
274:
3947:
3627:
Samsonov, G. V. & Serebryakova, T. I. (1978). "Classification of Borides".
3195:
S. M. Johnson; Matt Gasch; J. W. Lawson; M. I. Gusman; M. M. Stackpole (2009).
2888:
makes it an attractive control rod material when clad with a refractory metal.
2470:
using a molar ratio M:B of 1:4 at 700 °C for 30 minutes under argon flow.
5359:
5340:
5317:
4423:
4113:
4096:
3512:
2924:
resistance property of pure silicon carbide. The metal-like conductance of ZrB
2873:
2626:
can occur at temperatures in the range of 150–400 °C in order to prepare
2591:
2537:
2360:
2268:
2253:
1644:
some solid solution hardening effects arising from localized lattice strains.
478:
Table 1. Crystal structures, densities, and melting points of selected UHTCs.
330:
314:
246:
4707:
4273:Çamurlu, H. Erdem & Filippo Maglia. (2009). "Preparation of nano-size ZrB
4223:
Paul, A.; et al. (2012). "UHTC composites for hypersonic applications".
4004:
3987:
3520:
3212:
SHARP-B 2: Flight Test Objectives, Project Implementation and Initial Results
2386:
Another method for the synthesis of UHTCs is the borothermic reduction of ZrO
1520:
and nitride have values only around 20W/m*K). Thermal shock resistance of HfB
5033:
4351:"Preparation of ultrafine boride powders by metallothermic reduction method"
3496:
3059:
2881:
2770:
2627:
2177:
2116:
1559:
1223:
443:
363:
322:
278:
273:. Despite their advantages, UHTCs also have some limitations, such as their
4069:
3965:
3924:"Processing and Properties of High-Entropy Ultra-High Temperature Carbides"
3495:
Li, JinPing; Meng, SongHe; Han, JieCai; Zhang, XingHong (1 November 2008).
3481:
5294:
Welch, Barry J (1999). "Aluminum production paths in the new millennium".
1537:
in the range of 5.9–8.3 × 10 K.The structural and thermal stability of ZrB
4163:
https://ntrs.nasa.gov/api/citations/20040074335/downloads/20040074335.pdf
2885:
2649:
2645:
2197:
1271:, densities, and melting points of different UHTCs are shown in Table 1.
1231:
1227:
470:
and makes them ideal for many high-temperature thermal applications. The
434:) fractured between 14 and 19 seconds into reentry, two mid segments (ZrB
4578:
2590:. This synthesis route can be employed at low temperatures and produces
1238:
has one of the highest melting points of any material. Nitrides such as
4519:
4097:"Advances in ultra-high temperature ceramics, composites, and coatings"
4050:
3640:
2970:
2759:
2755:
1219:
1215:
227:
223:
5188:
Sonber, J. K.; et al. (2010). "Investigations on synthesis of HfB
3463:
3050:
2868:
depletion and faster burning of 11B. To help level out this bulge, ZrB
261:
components. They can be fabricated through various methods, including
4592:
Motojima, Seiji, Kimie Funahashi, and Kazuyuki Kurosawa. (1990). "ZrB
3859:
2933:
flexural strength was reduced from 500 MPa and 359 MPa in SiC and ZrB
219:
4502:
3836:
Munro, R. G. (1997). "Material Properties of a Sintered alpha-SiC".
3583:
3181:
3163:
3197:
Recent Developments in Ultra High Temperature Ceramics at NASA Ames
313:
at Manlabs Incorporated. Through a systematic investigation of the
3304:
Ultra High Temperature Ceramics: Application, Issues and Prospects
2438:
were successfully synthesized by Zoli's Reaction, reduction of TiO
2256:
and can be used to produce the diborides by SHS. Production of ZrB
2181:
380:
231:
241:
UHTCs are used in various high-temperature applications, such as
2812:. Vehicles with "sharp" leading edges have significantly higher
1588:
1574:
367:
2901:
and the bulk graphite electrode substrate. Bonding tiles of TiB
2848:
2366:
Boron carbide reductions can also be carried out via reactive
352:
129:
70:
29:
5199:
International Journal of Refractory Metals and Hard Materials
5144:
International Journal of Refractory Metals and Hard Materials
5091:
International Journal of Refractory Metals and Hard Materials
3876:
International Journal of Refractory Metals and Hard Materials
2762:
in particular has shown an increase in the toughness of HfB
2418:
Nanocrystals of group IV and V metal diborides such as TiB
2131:). It has been found that the oxidative resistance of HfB
4277:
powder by self-propagating high-temperature synthesis".
3497:"Valence electron structure and properties of the ZrO2"
150:
99:
2119:
and oxidation resistance by exploring composites with
5297:
Journal of the Minerals, Metals and Materials Society
3732:
Part II, AFML-TR-68-190, ManLabs Inc., Cambridge, MA
3629:
Sov. Powder Metall. Met.Ceram. (English Translation)
2528:
powders using the inorganic-organic precursors ZrOCl
145:
may be too technical for most readers to understand
5346:Journal of Electrical Engineering & Technology
2884:and low reactivity with refractory metals such as
2774:uniaxial pressure exerted on the sample material.
2691:have also been used during the hot pressing of ZrB
2092:. The metal component oxidizes to a gas such as CO
3501:Science in China Series E: Technological Sciences
438:/SiC) fractured, and no fore strake segments (ZrB
3839:Journal of Physical and Chemical Reference Data
3563:Samsonov, G. V. & Vinitskii, I. M. (1980).
3306:. 2nd Ceramic Leadership Summit, Baltimore, MD.
1618:and a reduction in grain size upon processing.
3757:
3755:
2321:are less expensive than those required by the
370:programs aimed at developing a fully reusable
3157:
3155:
3153:
3151:
3100:
3098:
3096:
3094:
3092:
8:
5192:and development of a new composite with TiSi
4991:: CS1 maint: multiple names: authors list (
4944:: CS1 maint: multiple names: authors list (
4810:: CS1 maint: multiple names: authors list (
4632:: CS1 maint: multiple names: authors list (
4334:: CS1 maint: multiple names: authors list (
3821:: CS1 maint: multiple names: authors list (
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3423:: CS1 maint: multiple names: authors list (
3369:: CS1 maint: multiple names: authors list (
3081:: CS1 maint: multiple names: authors list (
3386:Ceramic Science for Materials Technologists
2634:Processing of UHTCs and the addition of SiC
2194:self-propagating high-temperature synthesis
64:Learn how and when to remove these messages
4349:Nishiyama, Katsuhiro; et al. (2009).
2614:can also be used as a precursor in PECVD.
5358:
4518:
4376:
4199:
4112:
4059:
4049:
4003:
3955:
3789:
3471:
3058:
3011:
2754:phases include the addition of boron and
2399:due to the increased particle mixing and
2355:C, the ZrC phase disappears, and only ZrB
2156:is thinner than that on pure SiC, and HfB
191:Learn how and when to remove this message
173:Learn how and when to remove this message
157:, without removing the technical details.
118:Learn how and when to remove this message
3388:. Chapman & Hall. pp. 330–343.
2164:Synthesis of diboride (Zr, Hf, Ti) UHTCs
1650:
1633:which increases to 5.8 MPa m for ZrC-ZrO
1276:
480:
288:
94:Relevant discussion may be found on the
5160:University of South California, 1509920
5058:Journal of the European Ceramic Society
4919:Journal of the American Ceramic Society
4861:Journal of the European Ceramic Society
4785:Journal of the American Ceramic Society
4537:Journal of the American Ceramic Society
4507:Journal of the American Ceramic Society
4309:Journal of the European Ceramic Society
4280:Journal of the European Ceramic Society
3276:Journal of the European Ceramic Society
2947:
2656:lowers the operating temperature of ZrB
2586:) in the gaseous phase and use H2 as a
5239:
5228:
4984:
4937:
4803:
4625:
4327:
3814:
3737:
3605:
3416:
3362:
3335:
3324:
3074:
355:were found to be the best performing.
4356:Journal of Physics: Conference Series
4226:The American Ceramic Society Bulletin
4148:
4146:
4144:
4134:
4132:
4081:
4079:
4019:
4017:
4015:
3981:
3979:
3977:
3975:
3917:
3915:
3904:
3902:
3900:
3898:
3769:Journal of Physics: Conference Series
2991:Journal of Physics: Conference Series
2958:The Electrochemical Society Interface
2660:from 3,245 °C to 2,270 °C.
2598:on Cu at 700–900 °C (Figure 2).
2572:and boron halide precursors (such as
155:make it understandable to non-experts
7:
3762:Zhang, Guo-Jun; et al. (2009).
2984:Zhang, Guo-Jun; et al. (2009).
406:technique. 0.41 mm nozzle, 4x speed.
362:missions and the elimination of the
351:containing approximately 20% volume
4403:Journal of Thermal Spray Technology
2652:liquids. The addition of SiC to ZrB
5117:J.F. Justin; A. Jankowiak (2011).
5071:10.1016/j.jeurceramsoc.2005.05.011
4874:10.1016/j.jeurceramsoc.2009.03.008
4322:10.1016/j.jeurceramsoc.2009.07.006
4293:10.1016/j.jeurceramsoc.2008.09.006
3686:10.1023/b:jmsc.0000041691.41116.bf
3411:Bulletin 677, U.S. Bureau of Mines
3256:Johns Hopkins APL Technical Digest
3210:Salute, Joan; et al. (2001).
25:
4963:–SiC ceramics doped with boron".
4841:10.1016/j.matchemphys.2010.03.028
4448:Journal of the Less Common Metals
3707:Bansal, Narottam P., ed. (2004).
3128:Bansal, Narottam P., ed. (2004).
3105:Bansal, Narottam P., ed. (2004).
98:. Please help Knowledge (XXG) by
45:This article has multiple issues.
4979:10.1016/j.scriptamat.2009.03.030
4932:10.1111/j.1551-2916.2005.00739.x
4798:10.1111/j.1551-2916.2007.02217.x
4550:10.1111/j.1551-2916.2006.01269.x
4488:10.1016/j.scriptamat.2015.07.029
3565:Handbook of Refractory Compounds
2922:negative temperature coefficient
2839:. However, the boron in ZrB2|ZrB
134:
75:
34:
4890:Journal of Alloys and Compounds
4828:Materials Chemistry and Physics
4247:Surface and Coatings Technology
3537:Journal of Alloys and Compounds
3169:Journal of Propulsion and Power
2278:as reactants along with the ZrB
204:Ultra-high-temperature ceramics
90:of non-free copyrighted sources
53:or discuss these issues on the
18:Ultra high temperature ceramics
4768:ManLabs. Inc., Cambridge, Mass
4745:10.1179/1743676111y.0000000008
4378:10.1088/1742-6596/176/1/012043
4260:10.1016/j.surfcoat.2008.04.015
3791:10.1088/1742-6596/176/1/012041
3709:Handbook of Ceramic Composites
3130:Handbook of Ceramic Composites
3107:Handbook of Ceramic Composites
3013:10.1088/1742-6596/176/1/012041
2325:and borothermic reactions. ZrB
1535:thermal expansion coefficients
1:
5281:10.1016/s0022-3115(98)00059-2
4903:10.1016/j.jallcom.2007.10.137
4671:10.1016/s0040-6090(99)00721-x
4201:10.1080/17436753.2018.1509822
3600:10.1016/s0955-2219(99)00129-6
3550:10.1016/j.jallcom.2007.02.017
3289:10.1016/s0955-2219(02)00140-1
3241:10.1016/s0167-2738(02)00180-7
5260:Journal of Nuclear Materials
5212:10.1016/j.ijrmhm.2009.09.005
5104:10.1016/j.ijrmhm.2008.02.003
5013:Advances in Applied Ceramics
4724:Advances in Applied Ceramics
4620:10.1016/0040-6090(90)90028-c
4461:10.1016/0022-5088(68)90199-9
4180:Advances in Applied Ceramics
4101:Journal of Advanced Ceramics
3889:10.1016/j.ijrmhm.2013.12.011
3734:. IV: Mechanical Properties.
3665:Journal of Materials Science
3162:Sackheim, Robert L. (2006).
1214:at high temperatures. Metal
4858:–SiCw ceramic composites".
2403:that result from decreased
5407:
3948:10.1038/s41598-018-26827-1
3030:Journal of Applied Physics
5360:10.5370/jeet.2010.5.2.342
5318:10.1007/s11837-999-0036-4
4424:10.1007/s11666-010-9479-y
4114:10.1007/s40145-021-0550-6
3711:. Springer. p. 211.
3513:10.1007/s11431-008-0119-4
3109:. Springer. p. 192.
2566:Chemical vapor deposition
1206:UHTCs all exhibit strong
498:
495:
492:
489:
486:
483:
271:chemical vapor deposition
5339:Shin, Yong-Deok (2010).
4708:10.1002/adma.19920041005
4005:10.3390/coatings11121444
3302:Johnson, Sylvia (2011).
2747:Exaggerated grain growth
1511:Thermodynamic properties
1283:Thermal expansion (10/K)
5034:10.1179/174367606x69898
299:United States Air Force
5238:Cite journal requires
4566:Chemistry of Materials
3334:Cite journal requires
3037:(8): 083507–083507–4.
2738:Pressureless sintering
2297:Synthesis of UHTCs by
2252:. These reactions are
2090:operating temperatures
1663:Flexural Strength(MPa)
1253:hexagonal close-packed
493:Lattice parameters (Å)
407:
294:
267:spark plasma sintering
216:thermal conductivities
100:rewriting this article
3808:Mechanical Properties
3384:McColm, I.C. (1983).
2827:cross-section of 759
2616:Thermal decomposition
2415:during the reaction.
2168:UHTCs possess simple
1609:Mechanical properties
393:
372:hypersonic spaceplane
333:were used. Of these,
307:Boeing X-20 Dyna-Soar
292:
5127:Journal AerospaceLab
3594:(13–14): 2405–2414.
3283:(14–15): 2757–2767.
2821:corrosion resistance
2781:electrical discharge
2630:, conductive films.
2512:+ 4Na(g,l) + 2.5NaBO
2125:lanthanum hexaboride
1660:Young's Modulus(GPa)
1551:antibonding orbitals
1289:Thermal cond. (W/mK)
1212:structural stability
522:Hafnium carbonitride
319:thermal conductivity
102:with your own words.
5391:Composite materials
5381:Aerospace materials
5310:1999JOM....51e..24W
5273:1998JNuM..256..180C
5026:2005AdApC.104..273K
4737:2011AdApC.110..321S
4700:1992AdM.....4..650R
4663:2000TSF...359...68P
4612:1990TSF...189...73M
4579:10.1021/cm00035a013
4416:2010JTST...19..816K
4369:2009JPhCS.176a2043N
4192:2018AdApC.117S..70S
4042:2020Mate...13.1581S
3940:2018NatSR...8.8609C
3852:1997JPCRD..26.1195M
3811:. Part II, Vol. IV.
3782:2009JPhCS.176a2041Z
3717:2005hcc..book.....B
3678:2004JMatS..39.5951F
3456:2016NatSR...637962C
3142:2005hcc..book.....B
3115:2005hcc..book.....B
3043:2011JAP...110h3507L
3004:2009JPhCS.176a2041Z
2814:lift to drag ratios
2806:radius of curvature
2600:Plasma enhanced CVD
2493:(g) (M=Ti, Zr, Hf)
2084:Chemical properties
454:Physical properties
327:mechanical strength
303:hypersonic vehicles
255:hypersonic aircraft
212:refractory ceramics
4966:Scripta Materialia
4687:Advanced Materials
4520:10.1111/jace.15401
4476:Scripta Materialia
4051:10.3390/ma13071581
3928:Scientific Reports
3641:10.1007/bf00796340
3588:J. Eur. Ceram. Soc
3444:Scientific Reports
3228:Solid State Ionics
2971:10.1149/2.F04074IF
2825:neutron-absorption
2170:empirical formulas
1269:lattice parameters
408:
295:
277:and difficulty in
88:close paraphrasing
5386:Ceramic materials
5065:(13): 2431–2440.
4868:(13): 2893–2901.
4573:(11): 1659–1668.
4544:(11): 3585–3588.
4316:(16): 3401–3408.
4254:(18): 4394–4398.
3672:(19): 5951–5957.
3507:(11): 1858–1866.
3464:10.1038/srep37962
3051:10.1063/1.3647754
2835:with exposure to
2810:hypersonic flight
2485:+ 2Na(g,l) + NaBO
2081:
2080:
1530:thermal gradients
1508:
1507:
1292:Temperature (°C)
1265:thermal expansion
1210:which gives them
1199:
1198:
1033:Zirconium dioxide
937:Zirconium nitride
646:Zirconium carbide
490:Crystal structure
413:flexural strength
391:
325:, and reasonable
236:transition metals
201:
200:
193:
183:
182:
175:
128:
127:
120:
68:
16:(Redirected from
5398:
5365:
5364:
5362:
5336:
5330:
5329:
5291:
5285:
5284:
5267:(2–3): 180–188.
5254:
5248:
5247:
5241:
5236:
5234:
5226:
5222:
5216:
5215:
5185:
5179:
5178:
5170:
5164:
5163:
5155:
5149:
5148:
5138:
5132:
5131:
5123:
5114:
5108:
5107:
5081:
5075:
5074:
5052:
5046:
5045:
5003:
4997:
4996:
4990:
4982:
4956:
4950:
4949:
4943:
4935:
4913:
4907:
4906:
4897:(1–2): 506–511.
4884:
4878:
4877:
4851:
4845:
4844:
4835:(2–3): 470–473.
4822:
4816:
4815:
4809:
4801:
4792:(5): 1412–1415.
4778:
4772:
4771:
4763:
4757:
4756:
4718:
4712:
4711:
4681:
4675:
4674:
4650:Thin Solid Films
4644:
4638:
4637:
4631:
4623:
4599:Thin Solid Films
4589:
4583:
4582:
4560:
4554:
4553:
4531:
4525:
4524:
4522:
4513:(6): 2627–2637.
4498:
4492:
4491:
4471:
4465:
4464:
4442:
4436:
4435:
4389:
4383:
4382:
4380:
4346:
4340:
4339:
4333:
4325:
4303:
4297:
4296:
4287:(8): 1501–1506.
4270:
4264:
4263:
4241:
4235:
4234:
4220:
4214:
4213:
4203:
4171:
4165:
4159:
4153:
4150:
4139:
4136:
4127:
4126:
4116:
4092:
4086:
4083:
4074:
4073:
4063:
4053:
4021:
4010:
4009:
4007:
3983:
3970:
3969:
3959:
3919:
3910:
3906:
3893:
3892:
3870:
3864:
3863:
3860:10.1063/1.556000
3846:(5): 1195–1203.
3833:
3827:
3826:
3820:
3812:
3802:
3796:
3795:
3793:
3759:
3750:
3749:
3743:
3735:
3727:
3721:
3720:
3704:
3698:
3697:
3659:
3653:
3652:
3624:
3618:
3617:
3611:
3603:
3579:
3573:
3572:
3560:
3554:
3553:
3544:(1–2): 224–233.
3531:
3525:
3524:
3492:
3486:
3485:
3475:
3435:
3429:
3428:
3422:
3414:
3406:
3400:
3399:
3381:
3375:
3374:
3368:
3360:
3350:
3344:
3343:
3337:
3332:
3330:
3322:
3314:
3308:
3307:
3299:
3293:
3292:
3270:
3264:
3263:
3251:
3245:
3244:
3235:(3–4): 319–326.
3222:
3216:
3215:
3207:
3201:
3200:
3192:
3186:
3185:
3159:
3146:
3145:
3125:
3119:
3118:
3102:
3087:
3086:
3080:
3072:
3062:
3060:2060/20110015597
3024:
3018:
3017:
3015:
2981:
2975:
2974:
2952:
2837:thermal neutrons
2210:Reduction of ZrO
1651:
1556:bonding strength
1286:Temp. range (°C)
1277:
1208:covalent bonding
1167:Vanadium nitride
1067:Tantalum nitride
999:Vanadium carbide
906:Titanium nitride
810:Titanium carbide
742:Zirconium boride
584:Tantalum carbide
481:
468:shock resistance
448:grain boundaries
398:set of fins via
396:hafnium diboride
394:Production of a
392:
321:, resistance to
210:) are a type of
196:
189:
178:
171:
167:
164:
158:
138:
137:
130:
123:
116:
112:
109:
103:
79:
78:
71:
60:
38:
37:
30:
21:
5406:
5405:
5401:
5400:
5399:
5397:
5396:
5395:
5371:
5370:
5369:
5368:
5338:
5337:
5333:
5293:
5292:
5288:
5256:
5255:
5251:
5237:
5227:
5224:
5223:
5219:
5195:
5191:
5187:
5186:
5182:
5172:
5171:
5167:
5157:
5156:
5152:
5140:
5139:
5135:
5121:
5116:
5115:
5111:
5087:
5083:
5082:
5078:
5054:
5053:
5049:
5009:
5005:
5004:
5000:
4983:
4962:
4958:
4957:
4953:
4936:
4915:
4914:
4910:
4886:
4885:
4881:
4857:
4853:
4852:
4848:
4824:
4823:
4819:
4802:
4780:
4779:
4775:
4765:
4764:
4760:
4720:
4719:
4715:
4694:(10): 650–653.
4683:
4682:
4678:
4646:
4645:
4641:
4624:
4595:
4591:
4590:
4586:
4562:
4561:
4557:
4533:
4532:
4528:
4500:
4499:
4495:
4473:
4472:
4468:
4444:
4443:
4439:
4399:
4395:
4391:
4390:
4386:
4348:
4347:
4343:
4326:
4305:
4304:
4300:
4276:
4272:
4271:
4267:
4243:
4242:
4238:
4222:
4221:
4217:
4173:
4172:
4168:
4160:
4156:
4151:
4142:
4137:
4130:
4094:
4093:
4089:
4084:
4077:
4023:
4022:
4013:
3985:
3984:
3973:
3921:
3920:
3913:
3907:
3896:
3872:
3871:
3867:
3835:
3834:
3830:
3813:
3804:
3803:
3799:
3761:
3760:
3753:
3736:
3729:
3728:
3724:
3706:
3705:
3701:
3661:
3660:
3656:
3626:
3625:
3621:
3604:
3581:
3580:
3576:
3562:
3561:
3557:
3533:
3532:
3528:
3494:
3493:
3489:
3437:
3436:
3432:
3415:
3408:
3407:
3403:
3396:
3383:
3382:
3378:
3361:
3356:Radex Rundschau
3352:
3351:
3347:
3333:
3323:
3316:
3315:
3311:
3301:
3300:
3296:
3272:
3271:
3267:
3253:
3252:
3248:
3224:
3223:
3219:
3209:
3208:
3204:
3194:
3193:
3189:
3182:10.2514/1.23257
3161:
3160:
3149:
3136:. p. 198.
3127:
3126:
3122:
3104:
3103:
3090:
3073:
3026:
3025:
3021:
2983:
2982:
2978:
2954:
2953:
2949:
2944:
2936:
2932:
2927:
2919:
2908:
2904:
2900:
2895:
2871:
2852:
2842:
2793:
2786:
2779:to generate an
2765:
2752:
2731:
2727:
2720:
2716:
2710:
2706:
2702:
2698:
2694:
2689:
2685:
2678:
2674:
2659:
2655:
2636:
2625:
2621:
2609:
2597:
2584:
2577:
2560:
2556:
2551:
2547:
2535:
2531:
2527:
2519:
2515:
2511:
2507:
2503:
2499:
2492:
2488:
2484:
2480:
2476:
2469:
2465:
2461:
2457:
2453:
2449:
2445:
2441:
2437:
2433:
2429:
2425:
2421:
2410:
2401:lattice defects
2397:
2393:
2389:
2377:
2373:
2368:plasma spraying
2358:
2354:
2343:
2339:
2335:
2328:
2318:
2312:
2308:
2304:
2289:
2285:
2281:
2276:
2272:
2265:
2259:
2251:
2247:
2243:
2236:
2232:
2228:
2224:
2217:
2213:
2191:
2187:
2175:
2166:
2159:
2155:
2151:
2147:
2143:
2138:
2134:
2130:
2121:silicon carbide
2109:
2105:
2099:
2095:
2086:
1968:
1949:
1930:
1866:
1802:
1738:
1674:
1657:Temperature(°C)
1636:
1611:
1604:
1599:
1592:
1585:
1578:
1571:
1565:
1548:
1544:
1540:
1527:
1523:
1518:hafnium carbide
1513:
1430:
1412:
1394:
1374:
1319:
1300:
1261:single crystals
1250:
1246:
1204:
1191:unstable ?
1140:
1136:
1098:Niobium nitride
1040:
968:Silicon carbide
879:
872:Tantalum boride
848:
783:
776:Titanium boride
749:
715:
677:Hafnium nitride
615:Niobium carbide
553:Hafnium carbide
465:
461:
456:
441:
437:
433:
426:
422:
381:
345:
338:
287:
259:nuclear reactor
257:components and
197:
186:
185:
184:
179:
168:
162:
159:
151:help improve it
148:
139:
135:
124:
113:
107:
104:
93:
80:
76:
39:
35:
28:
23:
22:
15:
12:
11:
5:
5404:
5402:
5394:
5393:
5388:
5383:
5373:
5372:
5367:
5366:
5353:(2): 342–351.
5331:
5286:
5249:
5240:|journal=
5217:
5206:(2): 201–210.
5193:
5189:
5180:
5175:NASA Tm X-2963
5165:
5150:
5133:
5109:
5085:
5076:
5047:
5020:(6): 273–276.
5007:
4998:
4973:(2): 177–180.
4960:
4951:
4926:(2): 450–456.
4908:
4879:
4855:
4846:
4817:
4773:
4758:
4731:(6): 321–334.
4713:
4676:
4639:
4593:
4584:
4555:
4526:
4493:
4466:
4437:
4410:(4): 816–823.
4397:
4393:
4384:
4341:
4298:
4274:
4265:
4236:
4215:
4166:
4154:
4140:
4128:
4087:
4075:
4011:
3971:
3911:
3894:
3865:
3828:
3797:
3751:
3722:
3699:
3654:
3635:(2): 116–120.
3619:
3574:
3555:
3526:
3487:
3430:
3401:
3394:
3376:
3345:
3336:|journal=
3319:Swarthmore, PA
3309:
3294:
3265:
3246:
3217:
3202:
3187:
3147:
3120:
3088:
3019:
2976:
2946:
2945:
2943:
2940:
2934:
2930:
2925:
2917:
2906:
2902:
2898:
2893:
2869:
2850:
2840:
2792:
2789:
2784:
2763:
2758:. Addition of
2750:
2729:
2725:
2718:
2714:
2708:
2704:
2700:
2696:
2692:
2687:
2683:
2676:
2672:
2666:microstructure
2657:
2653:
2635:
2632:
2623:
2619:
2607:
2595:
2588:reducing agent
2582:
2575:
2558:
2554:
2549:
2545:
2542:phenolic resin
2533:
2529:
2525:
2520:(g) (M=Nb,Ta)
2517:
2513:
2509:
2505:
2501:
2497:
2490:
2486:
2482:
2478:
2474:
2467:
2463:
2459:
2455:
2451:
2447:
2443:
2439:
2435:
2431:
2427:
2423:
2419:
2408:
2405:particle sizes
2395:
2391:
2387:
2375:
2371:
2356:
2352:
2341:
2337:
2333:
2326:
2323:stoichiometric
2316:
2310:
2306:
2302:
2287:
2283:
2279:
2274:
2270:
2263:
2257:
2249:
2245:
2241:
2234:
2230:
2226:
2222:
2215:
2211:
2189:
2185:
2173:
2165:
2162:
2157:
2153:
2149:
2145:
2141:
2136:
2132:
2128:
2107:
2103:
2097:
2093:
2085:
2082:
2079:
2078:
2075:
2072:
2069:
2066:
2063:
2062:
2059:
2056:
2053:
2050:
2046:
2045:
2042:
2040:
2037:
2034:
2030:
2029:
2026:
2024:
2021:
2018:
2014:
2013:
2010:
2008:
2005:
2002:
1998:
1997:
1994:
1992:
1989:
1986:
1982:
1981:
1978:
1975:
1972:
1969:
1966:
1962:
1961:
1958:
1956:
1953:
1950:
1947:
1943:
1942:
1939:
1937:
1934:
1931:
1928:
1924:
1923:
1921:
1918:
1916:
1913:
1910:
1909:
1907:
1904:
1901:
1898:
1895:
1894:
1892:
1889:
1886:
1883:
1880:
1879:
1877:
1874:
1871:
1868:
1864:
1860:
1859:
1857:
1854:
1852:
1849:
1846:
1845:
1843:
1840:
1837:
1834:
1831:
1830:
1828:
1825:
1822:
1819:
1816:
1815:
1812:
1809:
1806:
1803:
1800:
1796:
1795:
1793:
1790:
1788:
1785:
1782:
1781:
1779:
1776:
1773:
1770:
1767:
1766:
1764:
1761:
1758:
1755:
1752:
1751:
1749:
1746:
1743:
1740:
1736:
1732:
1731:
1729:
1726:
1724:
1721:
1718:
1717:
1715:
1712:
1709:
1706:
1703:
1702:
1700:
1697:
1694:
1691:
1688:
1687:
1684:
1681:
1678:
1675:
1672:
1668:
1667:
1666:Hardness(GPa)
1664:
1661:
1658:
1655:
1634:
1610:
1607:
1602:
1597:
1590:
1583:
1576:
1569:
1563:
1546:
1542:
1538:
1525:
1521:
1512:
1509:
1506:
1505:
1502:
1499:
1496:
1493:
1489:
1488:
1486:
1484:
1481:
1478:
1474:
1473:
1471:
1469:
1466:
1463:
1459:
1458:
1456:
1454:
1451:
1448:
1444:
1443:
1440:
1437:
1434:
1431:
1428:
1424:
1423:
1421:
1419:
1416:
1413:
1410:
1406:
1405:
1403:
1401:
1398:
1395:
1392:
1388:
1387:
1384:
1381:
1378:
1375:
1372:
1368:
1367:
1364:
1361:
1358:
1355:
1351:
1350:
1347:
1344:
1341:
1338:
1334:
1333:
1330:
1327:
1324:
1321:
1317:
1313:
1312:
1309:
1306:
1304:
1302:
1298:
1294:
1293:
1290:
1287:
1284:
1281:
1248:
1244:
1203:
1200:
1197:
1196:
1193:
1187:
1184:
1181:
1178:
1175:
1172:
1169:
1163:
1162:
1159:
1156:
1153:
1150:
1147:
1144:
1141:
1138:
1134:
1131:
1129:Aluminum oxide
1125:
1124:
1121:
1118:
1115:
1112:
1109:
1106:
1103:
1100:
1094:
1093:
1090:
1087:
1084:
1081:
1078:
1075:
1072:
1069:
1063:
1062:
1059:
1056:
1053:
1050:
1047:
1044:
1041:
1038:
1035:
1029:
1028:
1025:
1019:
1016:
1013:
1010:
1007:
1004:
1001:
995:
994:
991:
988:
985:
982:
979:
976:
973:
970:
964:
963:
960:
957:
954:
951:
948:
945:
942:
939:
933:
932:
929:
926:
923:
920:
917:
914:
911:
908:
902:
901:
898:
895:
892:
889:
886:
883:
880:
877:
874:
868:
867:
864:
861:
858:
855:
852:
849:
846:
843:
841:Niobium boride
837:
836:
833:
830:
827:
824:
821:
818:
815:
812:
806:
805:
802:
799:
796:
793:
790:
787:
784:
781:
778:
772:
771:
768:
765:
762:
759:
756:
753:
750:
747:
744:
738:
737:
734:
731:
728:
725:
722:
719:
716:
713:
710:
708:Hafnium boride
704:
703:
700:
697:
694:
691:
688:
685:
682:
679:
673:
672:
669:
666:
663:
660:
657:
654:
651:
648:
642:
641:
638:
635:
632:
629:
626:
623:
620:
617:
611:
610:
607:
604:
601:
598:
595:
592:
589:
586:
580:
579:
576:
573:
570:
567:
564:
561:
558:
555:
549:
548:
545:
542:
539:
536:
533:
530:
527:
524:
518:
517:
514:
511:
508:
505:
501:
500:
499:Melting point
497:
496:Density (g/cm)
494:
491:
488:
485:
472:melting points
463:
459:
455:
452:
439:
435:
431:
424:
420:
343:
336:
286:
283:
199:
198:
181:
180:
142:
140:
133:
126:
125:
83:
81:
74:
69:
43:
42:
40:
33:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
5403:
5392:
5389:
5387:
5384:
5382:
5379:
5378:
5376:
5361:
5356:
5352:
5348:
5347:
5342:
5335:
5332:
5327:
5323:
5319:
5315:
5311:
5307:
5303:
5299:
5298:
5290:
5287:
5282:
5278:
5274:
5270:
5266:
5262:
5261:
5253:
5250:
5245:
5232:
5221:
5218:
5213:
5209:
5205:
5201:
5200:
5184:
5181:
5176:
5169:
5166:
5161:
5154:
5151:
5146:
5145:
5137:
5134:
5130:. 3, AL03-08.
5129:
5128:
5120:
5113:
5110:
5105:
5101:
5097:
5093:
5092:
5080:
5077:
5072:
5068:
5064:
5060:
5059:
5051:
5048:
5043:
5039:
5035:
5031:
5027:
5023:
5019:
5015:
5014:
5002:
4999:
4994:
4988:
4980:
4976:
4972:
4968:
4967:
4955:
4952:
4947:
4941:
4933:
4929:
4925:
4921:
4920:
4912:
4909:
4904:
4900:
4896:
4892:
4891:
4883:
4880:
4875:
4871:
4867:
4863:
4862:
4850:
4847:
4842:
4838:
4834:
4830:
4829:
4821:
4818:
4813:
4807:
4799:
4795:
4791:
4787:
4786:
4777:
4774:
4769:
4762:
4759:
4754:
4750:
4746:
4742:
4738:
4734:
4730:
4726:
4725:
4717:
4714:
4709:
4705:
4701:
4697:
4693:
4689:
4688:
4680:
4677:
4672:
4668:
4664:
4660:
4656:
4652:
4651:
4643:
4640:
4635:
4629:
4621:
4617:
4613:
4609:
4605:
4601:
4600:
4588:
4585:
4580:
4576:
4572:
4568:
4567:
4559:
4556:
4551:
4547:
4543:
4539:
4538:
4530:
4527:
4521:
4516:
4512:
4508:
4504:
4497:
4494:
4489:
4485:
4481:
4477:
4470:
4467:
4462:
4458:
4454:
4450:
4449:
4441:
4438:
4433:
4429:
4425:
4421:
4417:
4413:
4409:
4405:
4404:
4388:
4385:
4379:
4374:
4370:
4366:
4363:(1): 012043.
4362:
4358:
4357:
4352:
4345:
4342:
4337:
4331:
4323:
4319:
4315:
4311:
4310:
4302:
4299:
4294:
4290:
4286:
4282:
4281:
4269:
4266:
4261:
4257:
4253:
4249:
4248:
4240:
4237:
4232:
4228:
4227:
4219:
4216:
4211:
4207:
4202:
4197:
4193:
4189:
4185:
4181:
4177:
4170:
4167:
4164:
4158:
4155:
4149:
4147:
4145:
4141:
4135:
4133:
4129:
4124:
4120:
4115:
4110:
4106:
4102:
4098:
4091:
4088:
4082:
4080:
4076:
4071:
4067:
4062:
4057:
4052:
4047:
4043:
4039:
4035:
4031:
4027:
4020:
4018:
4016:
4012:
4006:
4001:
3997:
3993:
3989:
3982:
3980:
3978:
3976:
3972:
3967:
3963:
3958:
3953:
3949:
3945:
3941:
3937:
3933:
3929:
3925:
3918:
3916:
3912:
3905:
3903:
3901:
3899:
3895:
3890:
3886:
3882:
3878:
3877:
3869:
3866:
3861:
3857:
3853:
3849:
3845:
3841:
3840:
3832:
3829:
3824:
3818:
3810:
3809:
3801:
3798:
3792:
3787:
3783:
3779:
3776:(1): 012041.
3775:
3771:
3770:
3765:
3758:
3756:
3752:
3747:
3741:
3733:
3726:
3723:
3718:
3714:
3710:
3703:
3700:
3695:
3691:
3687:
3683:
3679:
3675:
3671:
3667:
3666:
3658:
3655:
3650:
3646:
3642:
3638:
3634:
3630:
3623:
3620:
3615:
3609:
3601:
3597:
3593:
3589:
3585:
3578:
3575:
3570:
3566:
3559:
3556:
3551:
3547:
3543:
3539:
3538:
3530:
3527:
3522:
3518:
3514:
3510:
3506:
3502:
3498:
3491:
3488:
3483:
3479:
3474:
3469:
3465:
3461:
3457:
3453:
3449:
3445:
3441:
3434:
3431:
3426:
3420:
3412:
3405:
3402:
3397:
3391:
3387:
3380:
3377:
3372:
3366:
3358:
3357:
3349:
3346:
3341:
3328:
3320:
3313:
3310:
3305:
3298:
3295:
3290:
3286:
3282:
3278:
3277:
3269:
3266:
3261:
3257:
3250:
3247:
3242:
3238:
3234:
3230:
3229:
3221:
3218:
3213:
3206:
3203:
3198:
3191:
3188:
3183:
3179:
3175:
3171:
3170:
3165:
3158:
3156:
3154:
3152:
3148:
3143:
3139:
3135:
3131:
3124:
3121:
3116:
3112:
3108:
3101:
3099:
3097:
3095:
3093:
3089:
3084:
3078:
3070:
3066:
3061:
3056:
3052:
3048:
3044:
3040:
3036:
3032:
3031:
3023:
3020:
3014:
3009:
3005:
3001:
2998:(1): 012041.
2997:
2993:
2992:
2987:
2980:
2977:
2972:
2968:
2964:
2960:
2959:
2951:
2948:
2941:
2939:
2923:
2914:
2912:
2889:
2887:
2883:
2877:
2875:
2867:
2862:
2857:
2856:uranium oxide
2853:
2846:
2838:
2834:
2830:
2826:
2822:
2817:
2815:
2811:
2807:
2801:
2799:
2790:
2788:
2782:
2777:
2772:
2769:Spark plasma
2767:
2761:
2757:
2748:
2744:
2739:
2735:
2732:
2721:
2690:
2679:
2667:
2661:
2651:
2647:
2642:
2641:Densification
2633:
2631:
2629:
2617:
2613:
2605:
2601:
2593:
2589:
2585:
2578:
2571:
2567:
2563:
2543:
2539:
2521:
2494:
2471:
2416:
2414:
2406:
2402:
2384:
2382:
2369:
2364:
2362:
2350:
2345:
2340:C + 3C → 2ZrB
2330:
2324:
2320:
2300:
2299:boron carbide
2295:
2293:
2292:acid leaching
2277:
2266:
2255:
2238:
2219:
2208:
2206:
2203:
2199:
2195:
2183:
2179:
2171:
2163:
2161:
2148:, SiC and HfB
2126:
2122:
2118:
2114:
2110:
2091:
2083:
2076:
2073:
2070:
2067:
2065:
2064:
2060:
2057:
2054:
2051:
2048:
2047:
2043:
2041:
2038:
2035:
2032:
2031:
2027:
2025:
2022:
2019:
2016:
2015:
2011:
2009:
2006:
2003:
2000:
1999:
1995:
1993:
1990:
1987:
1984:
1983:
1979:
1976:
1973:
1970:
1964:
1963:
1959:
1957:
1954:
1951:
1945:
1944:
1940:
1938:
1935:
1932:
1926:
1925:
1922:
1919:
1917:
1914:
1912:
1911:
1908:
1905:
1902:
1899:
1897:
1896:
1893:
1890:
1887:
1884:
1882:
1881:
1878:
1875:
1872:
1869:
1862:
1861:
1858:
1855:
1853:
1850:
1848:
1847:
1844:
1841:
1838:
1835:
1833:
1832:
1829:
1826:
1823:
1820:
1818:
1817:
1813:
1810:
1807:
1804:
1798:
1797:
1794:
1791:
1789:
1786:
1784:
1783:
1780:
1777:
1774:
1771:
1769:
1768:
1765:
1762:
1759:
1756:
1754:
1753:
1750:
1747:
1744:
1741:
1734:
1733:
1730:
1727:
1725:
1722:
1720:
1719:
1716:
1713:
1710:
1707:
1705:
1704:
1701:
1698:
1695:
1692:
1690:
1689:
1685:
1682:
1679:
1676:
1670:
1669:
1665:
1662:
1659:
1656:
1653:
1652:
1649:
1645:
1641:
1638:
1630:
1626:
1622:
1619:
1617:
1616:densification
1608:
1606:
1600:
1593:
1586:
1579:
1572:
1561:
1557:
1552:
1536:
1531:
1519:
1510:
1503:
1500:
1497:
1494:
1491:
1490:
1487:
1485:
1482:
1479:
1476:
1475:
1472:
1470:
1467:
1464:
1461:
1460:
1457:
1455:
1452:
1449:
1446:
1445:
1441:
1438:
1435:
1432:
1426:
1425:
1422:
1420:
1417:
1414:
1408:
1407:
1404:
1402:
1399:
1396:
1390:
1389:
1385:
1382:
1379:
1376:
1370:
1369:
1365:
1362:
1359:
1356:
1353:
1352:
1348:
1345:
1342:
1339:
1336:
1335:
1331:
1328:
1325:
1322:
1315:
1314:
1310:
1307:
1305:
1303:
1296:
1295:
1291:
1288:
1285:
1282:
1279:
1278:
1275:
1272:
1270:
1266:
1262:
1258:
1254:
1241:
1237:
1233:
1229:
1225:
1221:
1217:
1213:
1209:
1201:
1194:
1192:
1188:
1185:
1182:
1179:
1176:
1173:
1170:
1168:
1165:
1164:
1160:
1157:
1154:
1151:
1148:
1145:
1142:
1132:
1130:
1127:
1126:
1122:
1119:
1116:
1113:
1110:
1107:
1104:
1101:
1099:
1096:
1095:
1091:
1088:
1085:
1082:
1079:
1076:
1073:
1070:
1068:
1065:
1064:
1060:
1057:
1054:
1051:
1048:
1045:
1042:
1036:
1034:
1031:
1030:
1026:
1024:
1020:
1017:
1014:
1011:
1008:
1005:
1002:
1000:
997:
996:
992:
989:
986:
983:
980:
977:
974:
971:
969:
966:
965:
961:
958:
955:
952:
949:
946:
943:
940:
938:
935:
934:
930:
927:
924:
921:
918:
915:
912:
909:
907:
904:
903:
899:
896:
893:
890:
887:
884:
881:
875:
873:
870:
869:
865:
862:
859:
856:
853:
850:
844:
842:
839:
838:
834:
831:
828:
825:
822:
819:
816:
813:
811:
808:
807:
803:
800:
797:
794:
791:
788:
785:
779:
777:
774:
773:
769:
766:
763:
760:
757:
754:
751:
745:
743:
740:
739:
735:
732:
729:
726:
723:
720:
717:
711:
709:
706:
705:
701:
698:
695:
692:
689:
686:
683:
680:
678:
675:
674:
670:
667:
664:
661:
658:
655:
652:
649:
647:
644:
643:
639:
636:
633:
630:
627:
624:
621:
618:
616:
613:
612:
608:
605:
602:
599:
596:
593:
590:
587:
585:
582:
581:
577:
574:
571:
568:
565:
562:
559:
556:
554:
551:
550:
546:
543:
540:
537:
534:
531:
528:
525:
523:
520:
519:
515:
512:
509:
506:
503:
502:
482:
479:
476:
473:
469:
453:
451:
449:
445:
429:
417:
414:
405:
401:
397:
379:
377:
373:
369:
365:
361:
360:Space Shuttle
356:
354:
350:
346:
339:
332:
328:
324:
320:
316:
312:
311:Space Shuttle
308:
304:
300:
291:
284:
282:
280:
276:
272:
268:
264:
260:
256:
252:
248:
244:
239:
237:
233:
229:
225:
221:
217:
213:
209:
205:
195:
192:
177:
174:
166:
156:
152:
146:
143:This article
141:
132:
131:
122:
119:
111:
101:
97:
91:
89:
84:This article
82:
73:
72:
67:
65:
58:
57:
52:
51:
46:
41:
32:
31:
19:
5350:
5344:
5334:
5304:(5): 24–28.
5301:
5295:
5289:
5264:
5258:
5252:
5231:cite journal
5220:
5203:
5197:
5183:
5174:
5168:
5159:
5153:
5142:
5136:
5125:
5112:
5095:
5089:
5079:
5062:
5056:
5050:
5017:
5011:
5001:
4987:cite journal
4970:
4964:
4954:
4940:cite journal
4923:
4917:
4911:
4894:
4888:
4882:
4865:
4859:
4849:
4832:
4826:
4820:
4806:cite journal
4789:
4783:
4776:
4767:
4761:
4728:
4722:
4716:
4691:
4685:
4679:
4657:(1): 68–76.
4654:
4648:
4642:
4628:cite journal
4606:(1): 73–79.
4603:
4597:
4587:
4570:
4564:
4558:
4541:
4535:
4529:
4510:
4506:
4496:
4479:
4475:
4469:
4452:
4446:
4440:
4407:
4401:
4400:C Powders".
4387:
4360:
4354:
4344:
4330:cite journal
4313:
4307:
4301:
4284:
4278:
4268:
4251:
4245:
4239:
4230:
4224:
4218:
4183:
4179:
4169:
4157:
4104:
4100:
4090:
4033:
4029:
3998:(12): 1444.
3995:
3991:
3931:
3927:
3880:
3874:
3868:
3843:
3837:
3831:
3817:cite journal
3806:
3800:
3773:
3767:
3740:cite journal
3731:
3725:
3708:
3702:
3669:
3663:
3657:
3632:
3628:
3622:
3608:cite journal
3591:
3587:
3577:
3569:Plenum Press
3564:
3558:
3541:
3535:
3529:
3504:
3500:
3490:
3447:
3443:
3433:
3419:cite journal
3410:
3404:
3385:
3379:
3365:cite journal
3354:
3348:
3327:cite journal
3312:
3303:
3297:
3280:
3274:
3268:
3259:
3255:
3249:
3232:
3226:
3220:
3211:
3205:
3196:
3190:
3173:
3167:
3129:
3123:
3106:
3077:cite journal
3034:
3028:
3022:
2995:
2989:
2979:
2965:(4): 30–36.
2962:
2956:
2950:
2915:
2890:
2878:
2818:
2802:
2794:
2791:Applications
2776:Grain growth
2768:
2736:
2662:
2637:
2570:metal halide
2564:
2522:
2495:
2472:
2417:
2385:
2365:
2346:
2331:
2296:
2239:
2220:
2209:
2205:crystallites
2167:
2087:
1646:
1642:
1639:
1631:
1627:
1623:
1620:
1612:
1514:
1273:
1259:strength as
1205:
477:
457:
418:
409:
357:
305:such as the
296:
263:hot pressing
243:heat shields
240:
207:
203:
202:
187:
169:
163:January 2023
160:
144:
114:
108:January 2023
105:
85:
61:
54:
48:
47:Please help
44:
5098:: 177–180.
4482:: 100–103.
4186:: s70–s75.
4036:(7): 1581.
3934:(1): 8609.
3883:: 259–262.
2911:wettability
2833:radioactive
2612:borohydride
2413:boron oxide
2361:grain sizes
2233:+ 5Mg → ZrB
2113:brittleness
1637:(40 wt.%).
1453:1,027–2,027
1436:1,027–2,027
1257:anisotropic
1043:Monoclinic
975:Polymorphic
404:3D Printing
400:robocasting
331:grain sizes
329:when small
275:brittleness
5375:Categories
3395:0412003511
3359:: 568–585.
2942:References
2743:compaction
2604:deposition
2592:thin films
2538:boric acid
2381:flow rates
2254:exothermic
1686:21.2–28.4
349:composites
315:refractory
247:spacecraft
50:improve it
5326:110543047
5042:137453717
4753:136927764
4455:: 23–32.
4432:136019792
4210:139891152
4123:245426945
4030:Materials
3694:135860255
3649:137246182
3521:1862-281X
3450:: 37962.
3413:: 98–102.
3069:121755388
2771:sintering
2628:amorphous
2618:of Zr(BH)
2504:+ 6.5NaBH
2466:with NaBH
2202:precursor
2117:toughness
1560:unit cell
1326:400–1,600
1202:Structure
882:Hexagonal
851:Hexagonal
786:Hexagonal
752:Hexagonal
718:Hexagonal
444:heat flux
428:composite
376:NASA Ames
364:Air force
323:oxidation
279:machining
253:linings,
234:of early
96:talk page
86:contains
56:talk page
4233:: 22–28.
4107:: 1–56.
4070:32235467
3992:Coatings
3966:29872126
3482:27905481
3262:: 29–35.
3176:: 1310.
3134:Springer
2886:tungsten
2650:eutectic
2646:hardness
2394:, or HfO
2290:by mild
2198:porosity
1654:Material
1498:20–1,500
1483:20–1,500
1468:20–1,500
1418:20–2,205
1400:20–2,205
1380:20–2,205
1360:20–1,500
1343:20–1,000
1280:Material
1216:carbides
1023:unstable
484:Material
309:and the
228:nitrides
224:carbides
5306:Bibcode
5269:Bibcode
5022:Bibcode
4733:Bibcode
4696:Bibcode
4659:Bibcode
4608:Bibcode
4412:Bibcode
4365:Bibcode
4188:Bibcode
4061:7177464
4038:Bibcode
3957:5988827
3936:Bibcode
3909:105248.
3848:Bibcode
3778:Bibcode
3713:Bibcode
3674:Bibcode
3473:5131352
3452:Bibcode
3138:Bibcode
3111:Bibcode
3039:Bibcode
3000:Bibcode
2823:, high-
2756:iridium
2548:and HfO
2477:+ 3NaBH
2374:and ZrO
2237:+ 5MgO
2214:and HfO
2135:and ZrB
1867:–20%SiC
1739:–20%SiC
1601:> VB
1558:in the
1541:and HfB
1524:and ZrB
1495:1.1–5.5
1320:–20%SiC
1301:–20%SiC
1247:and ZrB
981:Various
487:Formula
462:and HfB
285:History
251:furnace
220:borides
149:Please
5324:
5040:
4751:
4430:
4208:
4121:
4068:
4058:
3964:
3954:
3692:
3647:
3519:
3480:
3470:
3392:
3067:
2845:pellet
2622:to ZrB
2557:to ZrB
2407:of ZnO
2344:+ 4CO
1960:20.25
1504:1,500
1442:2,027
1332:1,000
1311:1,000
1189:2,050
1155:3.987
1152:4.750
1149:4.750
1146:4.750
1092:4,892
1061:4,919
1058:2,715
1021:2,810
993:4,613
962:5,342
931:5,342
900:5,504
866:3,050
835:5,612
804:5,837
770:5,873
736:6,116
702:6,125
671:6,152
609:6,814
578:7,156
547:7,430
544:4,110
541:12.65
529:Cubic
423:or ZrB
269:, and
232:oxides
230:, and
5322:S2CID
5122:(PDF)
5038:S2CID
4749:S2CID
4428:S2CID
4396:and B
4206:S2CID
4119:S2CID
3690:S2CID
3645:S2CID
3065:S2CID
2882:barns
2829:barns
2516:+ 13H
2508:→ 2MB
2446:, HfO
2442:, ZrO
2434:, TaB
2430:, NbB
2426:, HfB
2422:, ZrB
2390:, TiO
2260:from
2096:or NO
2068:1,000
2044:18.2
2028:30.0
2012:27.0
1996:26.0
1980:33.0
1941:25.0
1915:1,800
1900:1,400
1851:1,800
1836:1,400
1814:28.0
1787:1,800
1772:1,400
1723:1,800
1708:1,400
1594:>
1587:>
1580:>
1573:>
1323:5–7.8
1174:Cubic
1161:3762
1158:2072
1120:2,573
1117:8.470
1105:Cubic
1089:2,700
1086:14.30
1083:4.330
1080:4.330
1077:4.330
1074:Cubic
1055:5.68
1006:Cubic
990:2,545
959:2,950
953:4.578
950:4.578
947:4.578
928:2,950
922:4.242
919:4.242
916:4.242
897:3,040
894:12.54
891:3.227
885:3.098
860:3.311
854:3.085
832:3,100
826:4.327
823:4.327
820:4.327
817:Cubic
801:3,225
795:3.230
789:3.030
767:3,245
761:3.530
755:3.169
733:3,380
730:11.19
727:3.476
721:3.142
699:3,385
693:4.525
690:4.525
687:4.525
668:3,400
662:4.693
659:4.693
656:4.693
653:Cubic
637:3,490
634:7.820
622:Cubic
606:3,768
603:14.50
600:4.455
597:4.455
594:4.455
591:Cubic
575:3,958
572:12.76
569:4.638
566:4.638
563:4.638
526:HfCN
516:(°F)
208:UHTCs
5244:help
4993:link
4946:link
4812:link
4634:link
4336:link
4066:PMID
3962:PMID
3823:link
3746:link
3614:link
3517:ISSN
3478:PMID
3425:link
3390:ISBN
3371:link
3340:help
3083:link
2722:and
2703:, Yb
2680:and
2579:and
2574:TiCl
2540:and
2489:+ 6H
2481:→ MB
2458:, Ta
2450:, Nb
2332:2ZrO
2313:and
2309:/HfO
2305:/TiO
2282:/ZrO
2180:and
2127:(LaB
2077:8.9
1501:26.3
1439:36.2
1386:800
1366:800
1349:800
1230:and
1186:6.13
1143:HCP
1018:5.77
987:3.21
956:7.29
925:5.39
863:6.97
829:4.94
798:4.52
764:6.10
696:13.9
665:6.56
513:(°C)
402:, a
368:NASA
340:and
245:for
5355:doi
5314:doi
5277:doi
5265:256
5208:doi
5196:".
5100:doi
5067:doi
5030:doi
5018:104
5010:".
4975:doi
4928:doi
4899:doi
4895:465
4870:doi
4837:doi
4833:122
4794:doi
4741:doi
4729:110
4704:doi
4667:doi
4655:359
4616:doi
4604:189
4575:doi
4546:doi
4515:doi
4511:101
4484:doi
4480:109
4457:doi
4420:doi
4373:doi
4361:176
4318:doi
4289:doi
4256:doi
4252:202
4196:doi
4184:117
4109:doi
4056:PMC
4046:doi
4000:doi
3952:PMC
3944:doi
3885:doi
3856:doi
3786:doi
3774:176
3682:doi
3637:doi
3596:doi
3546:doi
3542:456
3509:doi
3468:PMC
3460:doi
3285:doi
3237:doi
3233:149
3178:doi
3055:hdl
3047:doi
3035:110
3008:doi
2996:176
2967:doi
2929:ZrB
2916:ZrB
2892:TiB
2864:235
2859:239
2847:of
2798:HTV
2581:BCl
2553:ZrO
2536:O,
2532:•8H
2524:ZrB
2349:ZrC
2336:+ B
2262:ZrO
2225:+ B
2221:ZrO
2192:by
2140:SiO
2074:397
2071:392
2061:32
2058:359
2055:415
2049:SiC
2039:285
2033:TaC
2023:451
2017:TiC
2007:348
2001:ZrC
1991:352
1985:HfC
1977:370
1974:551
1965:TiB
1955:539
1946:NbB
1936:257
1927:TaB
1920:270
1906:340
1903:430
1891:450
1888:500
1885:800
1876:400
1873:540
1863:ZrB
1856:200
1842:150
1839:360
1827:430
1824:480
1821:800
1811:380
1808:500
1799:ZrB
1792:280
1778:180
1775:410
1763:380
1760:530
1757:800
1748:420
1745:540
1735:HfB
1728:280
1714:170
1711:300
1699:570
1696:485
1693:800
1683:480
1680:530
1671:HfB
1596:NbB
1589:TaB
1582:ZrB
1575:TiB
1568:HfB
1492:SiC
1480:6.3
1477:TaC
1465:7.7
1462:TiC
1450:5.2
1447:ZrC
1433:8.4
1427:TaB
1415:8.3
1409:ZrB
1397:8.6
1391:TiB
1377:7.6
1371:HfB
1357:6.6
1354:HfC
1340:6.5
1337:HfN
1316:ZrB
1297:HfB
1240:ZrN
1236:HfC
1102:NbN
1071:TaN
1037:ZrO
972:SiC
944:FCC
941:ZrN
913:FCC
910:TiN
876:TaB
845:NbB
814:TiC
780:TiB
746:ZrB
712:HfB
684:FCC
681:HfN
650:ZrC
619:NbC
588:TaC
560:FCC
557:HfC
353:SiC
347:in
342:HfB
335:ZrB
153:to
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5343:.
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5302:51
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2454:BO
2383:.
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2294:.
2273:BO
2178:Zr
2052:23
2036:23
2020:23
2004:23
1988:23
1971:23
1952:23
1933:23
1870:23
1805:23
1742:23
1677:23
1605:.
1383:70
1363:30
1346:22
1329:78
1308:62
1232:Ta
1228:Ti
1226:,
1224:Zr
1222:,
1220:Hf
1195:-
1171:VN
1133:Al
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538:–
535:–
532:–
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