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Thermal Expansion of Three Group IVA Carbides to 2700oC
Journal of the American Ceramic Society
Abstract
X-ray thermal expansion measurements on arc- cast carbides of titanium, zirconium, and hafnium are reported. The coefficients of thermal expansion for these materials from room temperature to 2700°C are 9.5 ± 0.3 × 10−6/0C, 7.6 ± 0.2 × 10−6/0C, and 7.3 ± 0.2 × 10−6/0C, respectively.
... It is well known that the ground state of ZrC at room temperature is a rock-salt cubic structure named B1 [6,8]. Regarding various properties of the ZrC phase with the B1 structure, the experimental and calculated investigations in the literature are primarily focused on thermal expansion and heat capacity of ZrC, as well as mechanical properties and phase transitions from B1 to B2 (body-centered cubic ordered structure) [1][2][3][4][5][6][7][8][9]13,14]. Nevertheless, it should be pointed out that the experimental temperature-dependent thermodynamic and mechanical properties of ZrC have been obtained within a limited and dispersive temperature range (e.g., 500− 2500 °C [2], 5−350 K [3], 0−300 K [6], 0−1600 K [7]), and that the values of high pressure to induce the B1−B2 phase transition from various theoretical methods were quite different from each other [1][2][3][4][5][6][7][8]13,14]. ...
... Regarding various properties of the ZrC phase with the B1 structure, the experimental and calculated investigations in the literature are primarily focused on thermal expansion and heat capacity of ZrC, as well as mechanical properties and phase transitions from B1 to B2 (body-centered cubic ordered structure) [1][2][3][4][5][6][7][8][9]13,14]. Nevertheless, it should be pointed out that the experimental temperature-dependent thermodynamic and mechanical properties of ZrC have been obtained within a limited and dispersive temperature range (e.g., 500− 2500 °C [2], 5−350 K [3], 0−300 K [6], 0−1600 K [7]), and that the values of high pressure to induce the B1−B2 phase transition from various theoretical methods were quite different from each other [1][2][3][4][5][6][7][8]13,14]. ...
... Regarding various properties of the ZrC phase with the B1 structure, the experimental and calculated investigations in the literature are primarily focused on thermal expansion and heat capacity of ZrC, as well as mechanical properties and phase transitions from B1 to B2 (body-centered cubic ordered structure) [1][2][3][4][5][6][7][8][9]13,14]. Nevertheless, it should be pointed out that the experimental temperature-dependent thermodynamic and mechanical properties of ZrC have been obtained within a limited and dispersive temperature range (e.g., 500− 2500 °C [2], 5−350 K [3], 0−300 K [6], 0−1600 K [7]), and that the values of high pressure to induce the B1−B2 phase transition from various theoretical methods were quite different from each other [1][2][3][4][5][6][7][8]13,14]. ...
First principles calculation and quasi-harmonic Debye model were used to obtain more physical properties of zirconium carbide under high temperature and high pressure. The results show that the B1 structure of ZrC is energetically more favorable with lower heat of formation than the B2 structure, and that mechanical instability and positive heat of formation induce the inexistence of the B2 structure at normal pressure. It is also found that the B1 structure would transform to the B2 structure under high pressure below the critical point of V/V0=0.570. In addition, various thermodynamic and elastic properties of ZrC are obtained within the temperature range of 0–3000 K and the pressure range of 0–100 GPa. The calculated results not only are discussed and understood in terms of electronic structures, but also agree well with corresponding experimental data in the literature.
... c [37], experiments for (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C. j [97], experiments between 300 and 3000 K for TiC0.73, ZrC0.75, and HfC0.88. ...
... t [90], experiment: TiC0. 97. The average linear thermal expansion has been measured between 300 and 1600 K. w [101], ab initio calculations. ...
Available information concerning the elastic moduli of refractory carbides at temperatures (T) of relevance for practical applications is sparse and/or inconsistent. We carry out ab initio molecular dynamics (AIMD) simulations at T = 300, 600, 900, and 1200 K to determine the temperature-dependences of the elastic constants of rocksalt-structure (B1) TiC, ZrC, HfC, VC, and TaC compounds as well as multicomponent high-entropy carbides (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C. The second order elastic constants are calculated by least-square fitting of the analytical expressions of stress vs. strain relationships to simulation results obtained from three tensile and three shear deformation modes. Moreover, we employ sound velocity measurements to evaluate the bulk, shear, elastic moduli and Poisson's ratios of single-phase B1 (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C at ambient conditions. Our experimental results are in excellent agreement with the values obtained by AIMD simulations. In comparison with the predictions of previous ab initio calculations - where the extrapolation of finite-temperature elastic properties accounted for thermal expansion while neglecting intrinsic vibrational effects - AIMD simulations produce a softening of elastic moduli with T in closer agreement with experiments. Results of our simulations show that TaC is the system which exhibits the highest elastic resistances to both tensile and shear deformation up to 1200 K, and identify the high-entropy (V,Nb,Ta,Mo,W)C system as candidate for applications that require good ductility and toughness at room as well as elevated temperatures.
... We can observe that at 1800 K, the oxide layer that forms on HfC is rough and broken into several fragments, whereas the oxide layer that forms on ZrC materials looks quite smooth and well adherent to the carbide. This could be explained by a difference in the thermal expansion coefficient: HfC has a higher linear coefficient of thermal expansion than HfO 2 (up to 1670 K: 7.3 × 10 −6 K −1 vs. 5.8 × 10 −6 K −1 , respectively), 21,22 so the oxide layer tends to break due to the expansion of the carbide. On the other hand, ZrC has a lower coefficient than ZrO 2 (up to 1670 K: 7.6 × 10 −6 K −1 vs. 8 × 10 −6 K −1 , respectively), 21,22 that means that the oxide could dilate more than the carbide and results in a complete coverage of the carbide. ...
... This could be explained by a difference in the thermal expansion coefficient: HfC has a higher linear coefficient of thermal expansion than HfO 2 (up to 1670 K: 7.3 × 10 −6 K −1 vs. 5.8 × 10 −6 K −1 , respectively), 21,22 so the oxide layer tends to break due to the expansion of the carbide. On the other hand, ZrC has a lower coefficient than ZrO 2 (up to 1670 K: 7.6 × 10 −6 K −1 vs. 8 × 10 −6 K −1 , respectively), 21,22 that means that the oxide could dilate more than the carbide and results in a complete coverage of the carbide. At 2000 K, HCM still appears rough and porous and has a bigger volume than the starting disc. ...
Future receivers of concentration solar power plants have to heat the coolant (air) so that its temperature will exceed 1300 K. Such absorbers require materials able to support thermal and mechanical stresses, with the slowest possible oxidation kinetics at very high temperatures. Zirconium carbide (ZrC) with silicon additive like molybdenum disilicide (MoSi2) could be a candidate material for such an application. ZrC/20 vol% MoSi2 samples were oxidized for 20 min at the 5 kW Odeillo solar furnace in air at various temperatures between 1800 and 2000 K and the oxidation behaviour was investigated as a function of the exposure temperature and the surface machining preparation. X-Ray photoelectron spectroscopy and scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy enabled to study the microstructure evolution and to identify the oxidation mechanism leading to the formation of zirconia and silica layers. Based upon the characterizations, we can affirm that ZrC/20 vol% MoSi2 seems able to withstand temperatures up to 2000 K in air.
... Preeminent examples are the borides and carbides of Zr and Hf [3]. While the carbides have higher melting temperatures, lower coefficients of thermal expansion (CTE) [4,5] and are more elastically isotropic owing to their cubic B1 structure, their hexagonal (C32) diboride counterparts have generally received more attention because of their higher thermal conductivities [6,7], and oxidation resistance [6,8]. Nevertheless, the oxidation resistance of the pure diborides is inadequate above ∼1200 • C owing to the volatilization of the nominally protective B 2 O 3 amorphous layer produced during oxidation. ...
The oxidation behavior of an ultra-high temperature ceramic (UHTC) based on HfB2 with 20vol% SiC and was studied following two 10 min arc-jet test cycles with nominal heat flux of 350 W cm−2, stagnation pressure of 7 kPa, and a sustained peak surface temperature of 2360 °C. Microstructure characterization revealed a modified, layered structure comprising ∼390 μm of porous HfO2 at the surface and an underlying ∼740 μm porous region containing un-oxidized HfB2 over the bulk UHTC, unaffected below the oxidation front. The SiC presumably undergoes active oxidation, as commonly reported for temperatures above ∼1600 ± 100 °C. However, unlike typical of exposures below ∼2000 °C no molten silicate phase was present at the surface to mediate the exchange of oxidant and gaseous reaction products. Additionally, a HfC impurity phase oxidizes concurrently with SiC rather than HfB2. A thermodynamic analysis is provided to explain the observed behavior and the differences with lower temperature scenarios in the literature.
... 8 ZrC has been shown to have ductility at high temperatures, which could offer improved fracture toughness. 9 The CTE mismatch between ZrB 2 (~5.2 ppm/K at 298 K) 2,10 and ZrC (6.7 to 7.6 ppm/K at 298 to 2973 K) 11,12 results in residual tensile stress in the ZrC and compressive stresses in the ZrB 2 matrix. Further, the presence of a second phase should reduce grain growth at elevated temperatures through grain-boundary pinning, maintaining a fine grain size and improving strength at temperature. ...
The mechanical properties of a ZrB2-10 vol% ZrC ceramic were measured up to 2300°C in an argon atmosphere. Dense billets of ZrB2-9.5 vol% ZrC-0.1 vol% C were produced by hot-pressing at 1900°C. The ZrB2 grain size was 4.9 μm and ZrC cluster size was 1.8 μm. Flexure strength was 695 MPa at ambient, decreasing to 300 MPa at 1600°C, increasing to 345 MPa at 1800°C and 2000°C, and then decreasing to 290 MPa at 2200°C and 2300°C. Fracture toughness was 4.8 MPa·m½ at room temperature, decreasing to 3.4 MPa·m½ at 1400°C, increasing to 4.5 MPa·m½ at 1800°C, and decreasing to 3.6 MPa·m½ at 2300°C. Elastic modulus calculated from the crosshead displacement was estimated to be 505 GPa at ambient, relatively unchanging to 1200°C, then decreasing linearly to 385 GPa at 1600°C, more slowly to 345 GPa at 2000°C, and then more rapidly to 260 GPa at 2300°C. Surface flaws resulting from machining damage were the critical flaw up to 1400°C. Above 1400°C, plasticity reduced the stress at the crack tip and the surface flaws experienced subcritical crack growth. Above 2000°C, microvoid coalescence ahead of the crack tip caused failure.
... In contrast to oxide and nitride additions, the mechanical properties of ZrB 2 -SiC ceramics with ZrC (Table 8.4) typically result in mechanical properties similar to ZrB 2 -SiC without ZrC additions (Table 8.3). This is most likely the result of closer CTE match between ZrC (7.6 × 10 −6 K −1 ) [78] and ZrB 2 compared to SiC and ZrB 2 , resulting in the SiC phase still dominating the mechanical behavior. With ZrC additions from 5 to 30 vol%, the flexure strengths (~500-750 MPa), fracture toughnesses (3.5-6.5 MPa · m ½ ) are nominally the same as ZrB 2 -SiC. ...
This chapter discusses the current state-of-the-art in mechanical properties of zirconium diboride based Ultra-High temperature ceramics. The properties covered include the elastic modulus, strength, and fracture toughness at both ambient and elevated temperatures. The discussion concentrates on monolithic zirconium diboride, and zirconium diboride with additions of silicon carbide and/or transition metal disilicides as a second phase. The effect of microstructure and impurities on the mechanical properties will be discussed. An example is the finding that the morphology of the second phase, and its distribution, controls the mechanical properties of in ZrB2-based ceramics. The chapter will also discuss the improvements in mechanical properties that have been obtained using modern powders and processing techniques compared to historic studies from the 1960s. For example, an improvement in the strength of monolithic ZrB2 at 2200°C has recently been realized, from 50 MPa for the historic material to 200 MPa for the modern material. The chapter concludes with suggestions for improving the mechanical properties of diborides and recommendations for future studies.
... This is a characteristic of the presence of oxygen in the carbide lattice forming a cubic oxycarbide phase of the form HfC x O 2(1−x) . [23][24][25][26] The constant value of the lattice parameter suggested that oxygen/carbon ratio was unchanged during this stage of reduction. Stage II: this stage takes place between 3 and 7 h of the electrodeoxidation and it is characterised by the decrease of the CaHfO 3 peaks and the increase of the HfC x O 2(1−x) peaks. ...
Nanocrystalline powder of hafnium-rich-HfC has been successfully synthesised by the electro-deoxidation of HfO2–carbon precursors in molten chloride. The progress of the solid state reduction was monitored ex situ by analysing partially reduced samples using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been shown that the reduction started by converting HfO2 to CaHfO3 and an oxycarbide phase of the form HfCxO2(1−x). The CaHfO3 phase then also reduced to give HfCxO2(1−x), which subsequently reduced to HfC by ionising oxygen. The morphological analysis indicated almost no growth in the grain size occurred during the course of the electro-deoxidation. This investigation showed some loss of carbon during the electro-deoxidation resulted in metallic rich HfC. The synthesised powder exhibited better sinterability than the commercial HfC powder. Using the synthesised powder, fully dense monolithic HfC ceramics were produced by pressureless sintering at 1973 K with average grain size of about 3 μm.
... The characteristic feature of graphite flakes in the hot-pressed HMC is connected with great difference between matrix and inclusion phases in linear coefficients of thermal expansion a (CTEs). The CTEs for the group 4 transitionmetal carbides (a matrix ) lie in the interval from 7 Â 10 À6 to 9.5 Â 10 À6 1/K [7], whereas extremely anisotropic in thermal expansion behavior, the graphite phase possesses completely different CTEs in both main crystallographic directions: 1.5 Â 10 À6 1/K along the (00 l) planes and 45 Â 10 À6 1/K along the normal to these planes [8], with a coefficient of anisotropy z ¼ a paral / a perp % 30; so the following inequalities characterize the two-phase system state: ...
Hetero-modulus ceramics (or hetero-modulus ceramic-ceramic composites, HMC) are thermal shock-resistant materials, which can be applied, due to their less common microstructures and physicochemical properties, in aerospace and nuclear engineering and in various media, including the extreme environments, at high and ultrahigh temperatures. The main feature of this type of composite materials is the combination of hard ceramics having high Young's modulus with the low-modulus phases of graphite and graphite-like boron nitride. In contrast with various carbon-carbon composites, the HMC, treated by the ridge-effect knowledge-based technique, can be coated by the self-assembling (synergetic) protective scales functionally graded, which are perfectly adhered with the substrate due to formation of intermedi-ate carbon-doped oxide/oxycarbide layers and conserving the continuous (throughout the scales as well as substrate) reinforcement. TSR of hetero-modulus ceramics can be optimized by the microstructure design on the basis of the special approach described. Hetero-modulus ceramics (HMC) present an opportunity to combine a ceramic matrix having high Young's modulus (250–600 GPa) with inclusions of phases having considerably lower values of Young's modulus (15–30 GPa), such as graphite and graphite-like boron nitride. Subse-quently, it becomes more effective to use brittle materials (carbides, nitrides, borides, oxides, etc.) in the most modern ultrahigh temperature applications. The discovery of ridge effect in the oxidation of carbide-carbon hetero-modulus ceramics put forward this type of ultrahigh temperature materials in the leading position.
... The steel X2CrNiMo 18-14-3 was used in the experiment, but the viscoplastic and isotropic hardening material properties of the stainless steel 316L were used in the simulation (Bauccio, 1993;Brinkman, 2001;Wellinger and Gimmel, 1955;McQueen and Ryan, 2002;Spittel and Spittel, 2009;Umezawa and Ishikawa, 1992;Wegst and Wegst, 2010). The filler alloy was considered to have viscoplasticity and an isotropic hardening behavior (Hahn, 1970;Neilsen, 2003;Neilsen et al., 1996;Simon et al., 1992;Stephens, 1996;Waterhou and Yates, 1968;Wesgo, 2009) and the TiC interlayer was considered as elastic (Gauthier, 1995;Graham, 1965;Haddad et al., 1949;Hannink and Murray, 1974;Lipatnikov and Gusev, 1999;Richardson, 1965;Zapadaeva et al., 1981). ...
Thermal residual stresses are one of the crucial parameters in engineered grinding tool (EGT) life and its consistency. Predicting failure of brazed diamond metal joints in EGTs is related to analyzing the thermal residual stresses during the cooling process. Thus thermal residual stresses have been simulated in a model with realistic materials properties, for instance isotropic hardening and a hyperbolic-sine creep law for SS316L and the silver-copper-titanium active filler alloy, named Cusil ABA (TM). Also, special modeling techniques such as tie constraint and sub-modeling have been used to model an intermetallic layer titanium-carbide (TiC) with dimensions in nanometers, where the rest of the model's dimensions are in millimeters. To verify the simulated stress state of the diamond, Raman-active optical phonon modes at three different paths in the diamond were measured. As the experiments with Raman spectroscopy (RS) do not deliver stress components, the solution is to directly compute the peak shift of Raman spectrum. The splitting in phonon frequencies and the mixing of phonon modes contain information about the thermal residual stresses in the diamond. Finally the shift in the phonon frequencies was calculated from the different numerical residual elastic strain components and compared to the experimental results. (c) 2012 Elsevier Ltd. All rights reserved.
... The content of element Zr in the transitional region (IV) is higher than that in the region V, while the content of element Ti in the transitional region (IV) is lower than that in the region V. Therefore, from the element-scanning results of the carbides in samples H and L, more contents of Zr, representing ZrC, can be found in the transitional areas compared to the other areas and may lead to the relatively good combination between carbide and carbon matrix, because the coefficient of thermal expansion of ZrC (7.6 · 10 À6 /°C) is lower than that of TiC (9.5 · 10 À6 /°C) [18] and is relatively close to that of C/C composites (3.2-5.7 · 10 À6 /°C) [19]. ...
Carbon/carbon(C/C) composites infiltrated with Zr–Ti were prepared by chemical vapor infiltration and reactive melt infiltration. Their microstructure and ablation behavior at different temperatures and time were investigated. The results show that C/C composites infiltrated with Zr–Ti have good interface cohesion between carbon fibers, pyrocarbon and carbide. Compared with C/C composites and C/C–ZrC composites, the synthesized sample with Zr0.83Ti0.17C0.92 and Ti0.82Zr0.18C0.92 exhibits better ablation resistance at 2500 °C due to the newly formed protective layer composed of ZrTiO2 pinned by ZrO2 grains after ablation. The ablation resistance of the sample with Zr0.57Ti0.43C1.01 increased gradually with the decrease of temperature from 3000 °C to 2000 °C, whereas the ablation resistance of the sample with Zr0.83Ti0.17C0.92 and Ti0.82Zr0.18C0.92 first increased obviously and then decreased slightly. In addition, the work indicates that surplus particles or liquid phases of oxides cannot protect the matrix, and that the liquid oxides may even cause severe ablation. Furthermore, a protective layer of oxides tends to be formed with the increase of ablation time.
Laser gas-assisting processing of preprepared Ti6Al4V alloy is carried out and resulting surface topology, wetting state, metallurgical changes, and hardness are examined. A thin carbon film accommodating TiC and B4C particles is developed over the surface in the preparation cycle. Laser surface treatment consisting of surface ablation and melting is performed at constant laser scanning speeds and high-pressure nitrogen gas jet. Laser treatment results in surface texture topology with hierarchically distributed micro/nanopillars having 5.6 μm average surface roughness (Ra). The texture of the surface demonstrates a hydrophobic state with a contact angle of about 109° ± 3° and hysteresis of 37° ± 4°. The treated surface free energy yields ∼132 mJ/m², which is greater than that of TiC (∼120 mJ/m²). The high spreading rate of the molten alloy wets the surface of the hard particles while minimizing nano/mesopores around the particles in the treated layer. The presence of carbon film and TiC particles forms (Ti, Al)N, (Ti, Al)CxN1-x, TiN, TiNx, Ti2N, TiCxN1-x compounds on the surface, which contributes to microhardness enhancement in the treated zone. Surface microhardness of 1670 ± 50 HV is achieved, which remains higher than that of TiN coated, plasma nitrided, and laser nitrided surfaces.
In this work, a Zr–La–B–C(O)-based precursor-derived ceramic system is spark plasma sintered at 1600°C for 10 min. Chemical and phase analysis of the sintered ceramic reveals nanocrystalline ultra-high temperature (UHT) phases of ZrB2, ZrC, and La2Zr2O7 embedded in a glassy carbon matrix. A comprehensive evaluation of mechanical properties and thermal expansion characteristics correlates well with the presence of phases. Depth-sensing nanoindentation exemplifies high elastic recovery of 91% typically seen in glassy carbons. The hardness and Young’s modulus measured to be ∼4.5 and ∼29.5 GPa respectively, seem to be governed mainly by the presence of glassy carbon, and secondarily by stiff B–C bonds and the UHT phases. The linear coefficient of thermal expansion measured from 130°C to 1550°C is ∼7.9 × 10⁻⁶ K⁻¹ and the thermal expansion behaviour is found to be strongly driven by the constituent UHT phases.
The environmental barrier coating (EBC) has been studied to protect the silicon carbide blades of the next‐generation gas turbine engine of aircraft from superheated water vapor. The upper ceramic layer of EBC is brittle, therefore, cracks can occur under the impact of foreign debris and spread toward the lower layers, which leads to the destruction of this structure. Therefore, self‐healing structural ceramics is a promising solution to this problem, but they still have some critical drawbacks. First, a healing agent such as SiC is highly volatile in water vapor. Second, the uniform distribution of the healing agent in the matrix can cause internal stress, which can break the composite. Finally, in most cases, the self‐healing function can only be used once. Here, functionally graded Y2Ti2O7–Y2TiO5–TiN composites are produced by hot pressing and nitriding and then their self‐healing function is demonstrated. The oxidation of TiN to TiO2, associated with volumetric expansion, can heal surface cracks. In addition, the bending strength of the composite can be restored. The self‐healing ability is renewable at least until the second heating cycle. These optimistic results can pave the way for the development of a new class of materials with permanent self‐healing ability. This research introduces a novel heat‐treatment method for the manufacturing of Y2Ti2O7 composites with a functionally graded distribution of TiN nanoparticles healing agent. The Y2Ti2O7–TiN composite has the ability to self‐heal surface cracks, which can help recover the composite's bending strength. The healing agent is renewable and therefore the self‐healing function can repeat over many cycles.
Advanced concepts for in‐space propulsion require coatings that are resistant to erosion in high temperature and pressure hydrogen. The erosion of refractory carbides of interest for this application (ZrC, NbC, HfC, and TaC) is investigated using combined ab initio thermodynamic computations and equilibrium product analyses. The carbides are shown to erode through a combination of four governing reactions, the relative extents of which depend on environmental conditions. The product profiles from these reactions are complex but exhibit lower hydrogen saturation at higher temperature and lower pressures. A metric is derived to determine the applicability of equilibrium analyses for erosion rates, based on experimental conditions. Heritage mass loss experiments on ZrC in hydrogen satisfy the equilibrium criteria, and, correspondingly, the computed equilibrium erosion rate agrees quantitatively. The results suggest that previously postulated non‐equilibrium effects, namely the prolonged incongruent vaporization originating from high carbon mobility, does not drive erosion over the hours‐long timescales of the experiments. For specific in‐space propulsion designs, comparisons of carbide performance show TaC and HfC outperform other carbides and meet criteria needed to close designs.
Available information concerning the elastic moduli of refractory carbides at temperatures (T) of relevance for practical applications is sparse and/or inconsistent. Ab initio molecular dynamics (AIMD) simulations at T=300, 600, 900, and 1200 K are carried out to determine the temperature-dependences of the elastic constants of rocksalt-structure (B1) TiC, ZrC, HfC, VC, TaC compounds, as well as high-entropy (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C. The second-order elastic constants are calculated by least-square fitting of the analytical expressions of stress/strain relationships to simulation results obtained from three tensile and three shear deformation modes. Sound-velocity measurements are employed to validate AIMD values of bulk, shear, and elastic moduli of single-phase B1 (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C at ambient conditions. In comparison with the predictions of previous ab initio calculations – where the extrapolation of finite-temperature elastic properties accounted for thermal expansion while neglecting intrinsic vibrational effects – AIMD simulations produce a softening of shear elastic moduli with T in closer agreement with experiments. The results show that TaC is the system which exhibits the highest elastic resistances to tensile and shear deformation up to 1200 K, and indicate the (V,Nb,Ta,Mo,W)C system as candidate for applications that require superior toughness at room as well as elevated temperatures.
Similarly to other transition metals of group 4 – hafnium and zirconium, titanium forms with carbon, practically, the only one chemical compound (see also section C – Ti in Table I-2.13) – titanium monocarbide TiC1–x, having the broadest homogeneity range compared to all other refractory carbides of groups 4-5 [1-14]; although some low-temperature (< 600-1100 °C) ordered and metastable structures such as Ti2±xC (Fd(–3)m, R(–3)m, P3121, Pnma, P3m1, Pbcn, I41/amd, P4/mmm), Ti8C5±x (R(–3)m), Ti3C2±x (C2/m, I4/mmm, Immm, P(–3)m1, C2221), Ti4C3±x(P(–3)m1, C2/c, Pm(–3)m, I4/mmm), Ti5C4±x (P(–1), C2/m, I4/m), Ti6C5±x (C2/m, C2/c, P3112, P31, C2), Ti7C6±x (R(–3)) and Ti8C7±x (P4332, Fm(–3)m) [1, 14-41, 157, 445-450, 3297] and various molecular clusters Ti8C12 (Ti2C3), Ti8C13, Ti13C22 (TiC~2), C60Tix, C70Tix, including endohedral Ti2@C80, (Ti2C2)@C78, Ti@C28, C@Ti8C12, C2@Ti8C12 and nanocrystal Ti14C13, Ti17C19, Ti22C35, are also described in literature [42-57, 451-461, 491], they have not become attractive for any technical applications and often – not confirmed sufficiently.
Versatile chemical transformations of surface functional groups in 2D transition-metal carbides (MXenes) open up a new design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorganic salts. Successful synthesis of MXenes with O, NH, S, Cl, Se, Br, and Te surface terminations, as well as bare MXenes (no surface termination) was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interatomic distances in the MXene lattice, and Ti
n
+1C
n
(n = 1, 2) MXenes terminated with Te2- ligands show a giant, (>18%) in-plane lattice expansion compared to the bulk TiC lattice. Nb2C MXenes exhibited surface-group-dependent superconductivity.
Early transition metal carbides are considered to be superior candidate materials for oxidizing environments at temperatures exceeding 2000 °C. Generally, the remarkable oxidation resistance is largely attributed to a carbonaceous oxide interlayer (e.g. Hf‐O‐C, Zr‐O‐C, Ta‐O‐C etc.), locating at the interface between the external oxide layer and internal carbide (e.g. HfC, ZrC, TaC etc.), acts as the primary oxygen barrier. However, the oxygen barrier mechanism of the carbonaceous oxide interlayer remains unclear. Herein, through studying the oxidation behavior of a novel multicomponent carbide Hf0.5Zr0.3Ti0.2C in oxidizing environments up to 2500 °C, the oxygen barrier mechanism of the carbonaceous oxide was newly revealed. We found that the oxygen barrier resulted from the slow oxygen diffusion through the inner grains of Hf‐Zr‐Ti‐O due to the presence of carbon formed at the grain boundaries. Because of the existence of compact external oxide layer, beneath which the Hf‐Zr‐Ti‐O‐C interlayer possesses much lower oxygen activity and temperature that allow carbon to stably exist. This as‐formed carbon strongly retarded the fast diffusion of oxygen along the grain boundaries of oxides. Additionally, desirable synergisms of the designed multicomponent system, particularly, the outward short‐circuit diffusion of Ti leads to a self‐healing of the external oxide layer, evidently enhanced integral protection performance against oxidizing environments.
HfCx and HfCx based composites have been widely investigated since 1960s because of their outstanding properties and potential applications. This article reviews related studies about crystal structure, non-stoichiometric characteristic of HfCx, depending on carbon vacancy concentration in the crystal, and the tunable properties associated with this characteristic. Besides, different methods to synthesize HfCx powders and densification processes of bulk materials are also reviewed. Compared with traditional sintering methods, e.g. Hot Press Sintering (HPS) and Pressureless Sintering (PLS), Field Assisted Sintering Technique (FAST) and its reactive way (RFAST) are promising for the preparation of dense advanced materials with relatively uniform and finer microstructure at shorter time and lower temperature levels. HfCx and its based composites obtained from FAST usually exhibit better mechanical and physical performance than those sintered by traditional methods. In order to further improve the sinterability and mechanical properties of HfCx ceramics, sintering additives such as MoSi2, TaSi2, Si3N4 and SiC have been introduced. Addition of a certain amount of sintering aids like MoSi2 could lower the sintering temperature and obtain composites with finer grains and less defects, which greatly improve the high temperature mechanical properties of HfCx based composites, however, the properties could also be deteriorated if the addition is beyond proper range. Finally, excellent oxidation behavior of HfCx and HfCx composites over a wide range of temperatures (above 1800°C) is also discussed in this article.
A Cu-1.5 wt.%Ti/Diamond (55 vol.%) composite was fabricated by hot forging from powder mixture of copper, titanium and diamond powders at 1050 °C. A nano-thick TiC interfacial layer was formed between the diamond particle and copper matrix during forging, and it has an orientation relationship of (111)TiC//(002)Cu&[1 1¯ 0]TiC//[1 1¯ 0]Cu with the copper matrix. HRTEM analysis suggests that TiC is semi-coherently bond with copper matrix, which helps reduce phonon scattering at the TiC/Cu interface and facilitates the heat transfer, further leading to the hot-forged copper/diamond composite (referred as to Cu-Ti/Dia-0) has a thermal conductivity of 410 W/mK, and this is about 74% of theoretical thermal conductivity of hot-forged copper/composite (552 W/mK). However, the formation of thin amorphous carbon layer in diamond particle (next to the interfacial TiC layer) and deformed structure in the copper matrix have adverse effect on the thermal conductivity of Cu-Ti/Dia-0 composite. 800 °C-annealing eliminates the discrepancy in TiC interface morphology between the diamond-{100} and -{111} facets of Cu-Ti/Dia-0 composite, but causes TiC particles coarsening and agglomerating for the Cu-Ti/Dia-2 composite and interfacial layer cracking and spallation for the Cu-Ti/Dia-1 composite. In addition, a large amount of graphite was formed by titanium-induced diamond graphitization in the Cu-Ti/Dia-2 composite. All these factors deteriorate the heat transfer behavior for the annealed Cu-Ti/Dia composites. Appropriate heat treatment needs to be continually investigated to improve the thermal conductivity of hot-forged Cu-Ti/Dia composite by eliminating deformed structure in the copper matrix with limit/without impacts on the formed TiC interfacial layer.
Practically hafnium forms with carbon the only one chemical compound (see also section C–Hf in Table I-2.13) – hafnium monocarbide HfC1−x with extremely broad homogeneity range, apart from low-temperature (<510–530 °C) ordered and metastable structures of Hf2±xC (Fd(–3)m, R(–3)m, P3m1, Pnma, I41/amd, Pbcn, P4/mmm), Hf3C2±x (C2/m, I4/mmm, P(–3)m1, Immm), Hf4C3±x (C2/c, P(–3)m1, Pm(–3)m), Hf5C4±x (P(–1), C2/m, I4/m), Hf6C5±x (C2/m, C2/c, P3112), Hf7C6±x (R(–3)) and Hf8C7±x (P4332, Fm(–3)m) as well as molecular cluster Hf8C12, which are not confirmed sufficiently in literature.
Practically zirconium forms with carbon the only one chemical compound (see also section C–Zr in Table I-2.13) – zirconium monocarbide ZrC1–x with extremely broad homogeneity range, apart from low-temperature (<860–1080 °C) ordered structures of Zr2±xC (Fd(–3)m, R(–3)m, Pnma, P3m1, I41/amd, Pbcn, P4/mmm), Zr3C2±x (C2/m, P(–3)m1, I4/mmm, Immm), Zr4C3±x (C2/c, P(–3)m1, Pm(–3)m), Zr5C4±x (P(–1), C2/m, I4/m), Zr6C5±x (C2/m, C2/c, P3112), Zr7C6±x (R(–3)) and Zr8C7±x (P4332, Fm(–3)m) as well as molecular clusters Zr8C12, Zr13C22, Zr14C23, Zr18C29, Zr22C35, including endohedral C@Zr8C12, which are not confirmed sufficiently in literature.
Experimental results are presented on the average coefficient of the linear expansion of the zirconium carbide within the temperature range of 1200–2850 K. The ZrC specimens were prepared by spark plasma sintering from nanosize particles at 2100 K.
The authors conducted direct solid-state diffusion bonding of zirconium carbide (ZrC)-sintered materials with different average grain sizes of 3.5, 7.5 and 35 μm using a spark plasma sintering system. ZrC samples were bonded at 1300–2000 °C for 20 min with no defects or oxidation. Shear tests on the ZrC–ZrC joints at room temperature revealed that the bonding temperature to obtain joints with a strength at the bonding interface that is higher than the fracture strength of the base materials could be reduced by reducing the ZrC average grain size. Microstructure studies around the bonding interface showed that the bonding process was controlled by grain-boundary diffusion, and the dominant driving force was a lowering boundary energy at the intersection of the grain boundary and the bonding interface (i.e., triple junctions at the bonding interface). Grain boundary migration across the bonding interface at the triple junctions was suggested to increase joint strength. The higher density of the triple junctions derived from the reduced ZrC grain size is thought to enhance grain boundary migration and increase the driving force and diffusion paths for grain boundary diffusion, which results in the formation of joints with a higher bonding interface strength.
Zirconium carbide (ZrC) possesses a combination of thermodynamic, thermal, and mechanical properties that are promising for nuclear fuel applications requiring high-temperature resistance and structural integrity. This chapter reviews the literature evaluating ZrC properties as affected by temperature, as well as across the wide range of stoichiometry reported for ZrCx (x ≈ 0-0.5). Studies to date of the performance of ZrC under neutron and ion irradiation are summarized.
Research presented in this dissertation focused on the mechanical behavior of ZrB2 based ceramic at elevated temperatures. Flexure strength, fracture toughness, and elastic modulus were measured at temperatures up to 2300°C for three compositions: monolithic ZrB2 (Z); ZrB2 – 30 vol% SiC – 2 vol% B4C (ZS); and ZrB2 – 10 vol% ZrC (ZC). In argon, Z, ZS, and ZC had strengths of 210 (at 2300°C), 260 (at 2200°C), and 295 MPa (at 2300°C), the highest temperatures tested for each composition. Fractography was used extensively to characterize the strength limiting flaws as a function of temperature. Strength of ZS in argon was controlled by the SiC cluster size up to 1800°C, and the formation of B-O-C-N phases that bridged SiC clusters above 2000°C. For ZC, surface flaws introduced during specimen preparation were the source of critical flaws in the material up to 1400°C, sub-critical crack growth of surface flaws between 1600 and 2000°C, and microvoid coalescence above 2000°C.
It was also shown that thermal annealing at either 1400, 1500, or 1600°C improves the strength and modulus of ZS at temperatures between 800°C and 1600°C. Heat treatment at 1400°C for 10 hours produced the largest improvement in strength, 430 MPa at 1600°C versus 380 MPa for the as processed material. As a whole, the research pointed to several key microstructural features currently limiting the mechanical properties at the highest temperatures. In particular, removal of unfavorable secondary phases, and improved control over microstructure, should be promising methods to improve the elevated temperature properties of ZrB2 ceramics.
Introduction RMI Process Modeling Microstructure and Properties of Melt-Infiltrated Composites Applications Conclusions and Future Directions References
Carbon/carbon(C/C)–Zr–Ti–C composites were fabricated using chemical vapor infiltration and liquid metal infiltration processes. The residual thermal stress (RTS) distribution in the C/C–Zr–Ti–C composites was analyzed by Raman spectroscopy and finite element (FE) calculation. The mechanical behaviors of C/C–Zr–Ti–C composites with three types of carbon fiber preforms were tested. The results showed that there was very high compressive RTS in the fibers and high tensile RTS in the pyrocarbon (PyC) in the marginal region near the carbide. However, in the central region away from the carbide, relatively low compressive stress and tensile RTS were found in the fibers and PyC, respectively. The FE analysis showed that the introduction of carbide into the C/C composites caused a significant increase of the RTS in the PyC near the carbide, indicating that the carbide could change the RTS distribution in C/C composites. Moreover, the distribution of the RTS and its release combined with the carbide distribution and fiber architecture led to variations in the mechanical performance of composites with different preforms.
Zirconium carbide (ZrC) is a potential coating, oxygen-gettering, or
inert matrix material for advanced high temperature reactor fuels. ZrC
has demonstrated attractive properties for these fuel applications
including excellent resistance against fission product corrosion and
fission product retention capabilities. However, fabrication of ZrC
results in a range of stable sub-stoichiometric and carbon-rich
compositions with or without substantial microstructural inhomogeneity,
textural anisotropy, and a phase separation, leading to variations in
physical, chemical, thermal, and mechanical properties. The effects of
neutron irradiation at elevated temperatures, currently only poorly
understood, are believed to be substantially influenced by those
compositional and microstructural features further adding complexity to
understanding the key ZrC properties. This article provides a survey of
properties data for ZrC, as required by the United States Department of
Energy's advanced fuel programs in support of the current efforts toward
fuel performance modeling and providing guidance for future research on
ZrC for fuel applications.
Carbon-to-zirconium ratio (the product stoichiometry).
Chemical impurities.
Presence of secondary phases including grain boundary phases.
Grain size, morphology, orientation, and texture.
Porosity and pore size, distribution, and morphology.
Other forms of defects
Ultra-high temperature ceramics having melting points above 3500 K and high thermal conductivities are envisaged as future receivers of concentrating solar power plants. The high pressure and solar temperature reactor (Réacteur Hautes Pression et Température Solaire, REHPTS) implemented at the focus of the Odeillo 5 kW solar furnace was used to investigate the oxidation of three refractory carbides containing different sintering additives (HfC/MoSi2, ZrC/MoSi2, ZrC/TaSi2) that could be considered as promising candidates. The concentration of the additive, TaSi2 or MoSi2, was 20 vol%. Each kind of sample was oxidized in air for 20 min at 1800, 2000 and 2200 K. Experiments were filmed using a video camera and the gaseous phases were analyzed in situ by mass spectrometry. Various post-test characterizations have shown that the nature of the carbide and additive strongly affects the composition of the oxide layer and therefore the high-temperature behaviour.
A combined experimental/numerical approach was developed to determine the distribution of current density, temperature, and stress arising within the sample during spark plasma sintering (SPS) treatment of zirconium carbide (ZrCx) or oxycarbide (ZrCxOy). Stress distribution was calculated by using a numerical thermomechanical model, assuming that a slip without mechanical friction exists at the interfaces between the sample and the graphite elements. Heating up to 1950 °C at 100 °C min−1 and a constant applied pressure of 100 MPa were retained as process conditions. Simulated temperature distributions were found to be in excellent agreement with those measured experimentally. The numerical model confirms that, during the zirconium oxycarbide sintering, the temperature measured by the pyrometer on the die surface largely underestimates the actual temperature of the sample. This real temperature is in fact near the optimized sintering temperature for hot-pressed zirconium oxycarbide specimens. It is also shown that high stress gradients existing within the sample are much higher than the thermal ones. The amplitude of the stress gradients was found to be correlated with those of temperature even if they are also influenced by the macroscopic sample properties (coefficient of thermal expansion and elastic modulus). At high temperature, the radial and angular stresses, which are much higher than the vertical applied stress, provide the more significant contribution to the stress-related driving force for densification during the SPS treatment. The heat lost by radiation toward the wall chambers controlled both the thermal and stress gradients.
Thermal expansion of ZrC, which has the NaCI type structure, was determined from, 120 to 300 K by a powder X-ray diffraction method. The lattice parameter was measured precisely using a specially designed D-shaped symmetrical back-reflection-focusing camera with the specimen hanging from a cryoflask in the vacuum chamber outside the camera on the Rowland circle. The average coefficient of linear thermal expansion of ZrC in this temperature range is 6.22 x 10-6/K. The Zr/C ratio was 0.993.
Crystal structure of NaCl-type transition metal monocarbides MC (M=V, Ti, Nb, Ta, Hf and Zr) has been investigated by Rietveld analysis of neutron powder diffraction data measured at 23°C. The unit-cell parameter a of MC compounds increased with increasing of ionic radius of the metal species M. Structural change of the tantalum carbide TaC from 23 to 413°C has been investigated by Rietveld analysis of in situ neutron diffraction data. The unit-cell parameter a, unit-cell volume and atomic displacement parameter of TaC increased with increasing of temperature. The thermal expansion coefficient of TaC was estimated to be (6.4±0.3)×10−6°C−1.
Highly densified TiC, ZrC and HfC based ultrahigh temperature heteromodulus ceramics (HMC), containing 10?50?vol.?% of low modulus phase in the form of particulate graphite, were prepared by hot pressing at 2700?C and 12?MPa in argon atmosphere. The microstructure, elastic characteristics, flexural and compressive static strength, fracture toughness, impact resistance, hardness and thermal expansion were investigated and compared with those available in earlier works for clear understanding the composition?property correlations and anisotropy of this type of HMC composites. Different thermal shock resistant parameters for the HMC were calculated on the basis of obtained experimental data. A new principle of optimum materials design for the compositions in the refractory carbide?graphite systems is exemplified by the TiC?C HMC materials.
Many solid state properties are correlated to simple parameters like the atomic mass, the interatomic distance and some measure of the strength of the interatomic interaction, e.g. the melting temperature Tm or some Debye temperature θD. Such empirical relations are investigated for elastic properties, melting temperature, thermal expansion, vacancy formation energy, grain boundary and surface energy, cohesive energy, heat of fusion, activation energies for bulk, grain boundary, surface and dislocation pipe diffusion, viscosity, activation energy for creep, recrystallization temperature and other properties. When experimental data are available, both elements and diatomic compounds (alkali halides, oxides, carbides, III-V semiconductors) are considered. The correlations to Tm, θD(T = 0) and a high temperature effective θD are compared. It is found that for all practical purposes Tm gives the best correlation. For diatomic compounds, the average mass is not uniquely defined and various averages are discussed. The purpose of the paper is not only to present empirical relations but also to give a short account of the possibilities to calculate the considered parameters using solid state theory in its most advanced present state.
The solubility of WC in TiC was found to vary from 50 mol% at 2050°C to 75 mol% at 2350°C; WC was precipitated from solid solutions containing 75 mol% WC-25 mol% TiC and 65 mol% WC-35 mol% TiC at 1900°C. The precipitated WC occurred as well-aligned ribbon-shaped particles. The crystallographic orientation of the precipitate and the matrix established by electron diffraction techniques is [100]WC[110]TiC and [010]WC[001′]TiC. The interfacial planes were (001) for WC and (111) for TiC solid solution. Diffraction spot splitting occurred for all reflections of precipitated WC except the 001 type, indicating that compression of WC along the [110] direction took place, resulting in an apparent orthorhombic symmetry. This phenomenon was explained on the basis of the specific volumes and the difference in thermal expansion coefficient between WC and the solid solution. Tungsten carbide precipitated rapidly in the presence of Co, with all the WC precipitating in the form of platelets randomly oriented around the matrix grains. The hardness of the solid solutions 65 mol% WC-35 mol% TIC and 75 mol% WC-25 mol% Tic increased ∼10% and ∼23%, respectively, after they were annealed at 1900°C.
The emissivities of a typical carbon, graphite, and pyrolytic graphite possessing different surfaces were measured over the temperature range of 850° to 1800°C, utilizing an emissivity apparatus based upon a modification of the Fery rotating sample method. Results for graphite show that for a highly polished surface produced by burnishing the spectral emissivity is almost independent of temperature, while the integrated emissivity value shows a positive temperature dependence. After roughening the surface by various treatments, spectral values show a negative temperature coefficient, while integrated values are almost temperature independent. Carbon shows only slight changes in the emissivity with surface variations; a higher emissivity goes with rougher surfaces, but no change is observed in temperature dependence. These results are internally consistent and are interpreted on the basis of the surface treatment influencing the crystal orientation of the graphite surface. The differences in temperature dependence appear to be related to the anisotropic optical properties of graphite. Large optical anisotropy is to be expected in graphite due to the related electrical anisotropy that has been previously observed.
X-ray-powder-diffraction data are presented for ZrC with Miller indices ; assigned to approximate interplanar spacings. A lattice constant of 4.698 A is ; given for hafnium-free ZrC. For stoichiometric ZrC, the Zr-C bond distance for ; coordination number 6 is reported as 2.394 A and the theoretical density as 6.56 ; g per cc at 25 ction prod- C. (C.J.G.);
This report is the result of investigations of phase equilibria in the binary systems, zirconium-carbon, tantalum-carbon, and boron-carbon. A completed phase diagram which encompasses experimental results and considerations heretofore unreported in the literature, is presented for the zirconium-carbon system. A tentative phase diagram for the tantalum-carbon system is included, which, in general, resembles the version released by Ellinger in 1943. Preliminary results for the boron-carbon system, depicting maximum solubility in the graphite lattice below the eutectic temperature of approximately 2390 C, are also included. The zirconium-carbon system is characterized by eutectic temperatures of 1850 and 2850 C on the zirconium-rich and carbon rich sides of ZrC, respectively. The tantalum carbon system is characterized by two high temperature phases, TaC and Ta2C. A eutectic is observed at 2825 C between Ta and Ta2C. Below the B4C-C eutectic temperature of 2390 C, maximum boron solubilities in graphite are found to be 1.50, 2.25, and 2.75 atomic per cent at temperatures of 2000, 2200, and 2350 C, respectively.
The thermal expansion of HfC was measured with a Gaertner dilatation ; interferometer calibrated to an accuracy of plus or minus 1 deg F. Each run ; involved heating the test cones at about the rate of 8 deg F per minute to the ; desired test temperature and then cooling at the same rate. Density variation in ; the high-density range appeared to have no effect on the thermal expansion. The ; coefficient of thermal expansion was calculated to be 3.66 plus or minus 0.02 x ; 10â»â¶ per deg F from 77 to 1133 deg F or 6.59 plus or minus 0.04 x 10/sup ; -6/per deg C from 25to 612 deg C. (M.C.G.);
Thermal-expansion data on Al2O3, BeO, MgO, B4C, SiC, and TiC were obtained to the temperatures where permanent deformation begins, due to sintering or other causes. The thermal expansion for these materials was found to be approximately linear over the measured temperature range. But as a linear extrapolation to room temperature was not possible, the coefficient of thermal expansion is not a constant over this temperature range. The results are compared with the latest published data for each material. The average coefficients of linear thermal expansion are given as follows:
All BeO specimens which were heated to above 2050°C. had a very large expansion. Visual examination of the cooled specimens revealed that they had bent and cracked, the physical dimensions had enlarged, and the color had changed to a bright milky white. A brief discussion of the probable reasons for these changes is given. In the attempt to extend the expansion measurements, the melting point of BeO was obtained. A specimen of hot-pressed BeO melted at 2450°± 30°C., whereas a slip-cast BeO specimen melted at 2470°± 20° C.
A study of hard materials in an effort to find possible substitutes for industrial diamonds led to research on hafnium carbide. This compound was prepared from a mixture of hafnium dioxide and lampblack in a carbon resistance furnace by solid-state reaction or from a melt. Some factors affecting the combined carbon content of the re- action products were qualitatively evaluated. A hafnium carbide prepared from a melt at a temperature slightly above 2800°C. with no holding time had a combined carbon content within 98% of the theoretical value. A curve was obtained by plotting combined carbon against cubic unit- cell dimension (a0) for the hafnium carbide- “hafnium monoxide” solid solution series. Extrapolation gave 4.641 ± 0.001 a.u. for the cell edge of hafnium carbide of theoretical composition; a0 was observed as high as 4.640 a.u. Density values within 99% of theoretical were obtained. Knoop microindentation hardness measurements with both dry and oil-immersion objectives indicated a hardness in the silicon carbide range. Owing to its high cost and relatively low hard- ness, hafnium carbide is presently not considered to be a promising substitute for industrial diamonds.
Measurement of Thermal Expansion of Cermet Components of High Temperature X-Ray Diffraction
- F A Mauer
- L H Bolz
F. A. Mauer and L. H. Bolz, " Measurement of Thermal Ex-pansion of Cermet Components of High Temperature X-Ray Diffraction, " Air Research and Development Command, Wright-Patterson Air Force Base, Ohio, Report No. WADC-TR-55-473;
Preparation and Properties of Arc-Cast Tic-C Alloys Structural Changes in Pyrolytic Graphite at ElevatedTemperatures
- D H Leeds
- E G Kendall
- J F Ward
- S Doc
- J H Richardson
- E H Zehms
D. H. Leeds, E. G. Kendall, and J. F. Ward, " Preparation and Properties of Arc-Cast Tic-C Alloys, " N A S A Doc., N63-23781, 60 pp., September 1963. J. H. Richardson and E. H. Zehms, " Structural Changes in Pyrolytic Graphite at ElevatedTemperatures, " U. S. Dept. Comm., Ofice Tech. Serv., AD 427,346, 23 pp., December 1963. J. D. Plunkett and W. D. Kingery; pp. 457-72 in Proceed-ings of the 4th Conference on Carbon, Buffalo, 1959. Pergamon Press, New York, 1960. E. K. Storms, " Critical Review of Refractories: I " ; p. 11 in Los Alamos Scientific Laboratory, Report No. LAMS-2674;
Air Plasma Arc Materials Testing for Lifting Re-Entry, " pre-sented a t the Sixty-Sixth Annual Meeting, The American Ceramic SocietyCeramic-Metal Systems Division, No. 10-E-64); for abstract see Am
- D H Lceds
- D H Leeds
- W E Welsh
- J I Slaughter
- E G Kendall
D. H. Lceds, " Observations on the Thermal Shock Resistance of Tic-C Alloys, " presented a t 8th Refractories Composites T h e results in their study, a = 10.34 X Working Group Meeting ASD/NASA, Dallas, Texas, January 1964. D. H. Leeds, W. E. Welsh, J. I. Slaughter, and E. G. Kendall, " Air Plasma Arc Materials Testing for Lifting Re-Entry, " pre-sented a t the Sixty-Sixth Annual Meeting, The American Ceramic Society, April 21, 1964 (Ceramic-Metal Systems Division, No. 10-E-64); for abstract see Am. Ceram. SOC. Bull., 43 [4] 273 (1964).
Preparation and Properties of Are-Cast TiC-C Alloys
- D H Leeds
- E G Kendall
- J F Ward
Observations on the Thermal Shock Resistance of TiC-C Alloys
- D H Leeds
Critical Review of Refractories: I "; p.11 inLos Alamos Scientific Laboratory
- E K Storms