Oxidation of Hafnium Carbide in the Temperature Range 1400° to 2060°C

Bargeron, C. B.; Benson, Richard C.; Jette, A. Norman; Phillips, Terry E.

doi:10.1111/j.1151-2916.1993.tb05332.x

Cited by 123 publications

(66 citation statements)

References 13 publications

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“…Figure 3 shows that oxidation process of HfC starts at 800 • C. Comparing to the oxidation of pure TaC, the weight increases gradually instead of exhibiting a sharp increase, as evident from the slope. Such behavior is in accordance with the literature description of the oxidation behavior of HfC [12,22]. HfC has the ability to absorb oxygen without transforming into oxide.…”

Section: Mass Change During Thermogravimetric Analysis Of Carbide Solsupporting

confidence: 76%

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

et al. 2017

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Abstract:The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 • C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20), 50TaC-50 vol % HfC (T50H50), and 20TaC-80 vol % HfC (T20H80), in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 • C for pure TaC, to 940 • C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta 2 O 5 and HfC, which stabilizes the volume changes induced by the formation of Ta 2 O 5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions.

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Section: Mass Change During Thermogravimetric Analysis Of Carbide Solsupporting

confidence: 76%

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

et al. 2017

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“…The oxidation layer of HfO 2 is a porous scale, and the distribution of HfO 2 and B 2 O 3 in the oxide scale varies with temperatures. [8][9][10][11][12][13] At low temperatures (<$1273 K), a liquid B 2 O 3 film is formed on the top of HfO 2 plus B 2 O 3 scale, and the pores in the HfO 2 are covered or filled with glassy or liquid B 2 O 3 . At intermediate temperatures ($1273 to $2073 K), B 2 O 3 (l) would still partially fill the pores in porous HfO 2 even though the external B 2 O 3 (l) layer evaporates.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Calculation of HfB2 Volatility Diagram

Zhang

Zeng

et al. 2011

J. Phase Equilib. Diffus.

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The thermodynamics of the oxidation of HfB 2 at temperatures of 1000, 1500, 2000, and 2500 K have been studied using volatility diagrams. Both the equilibrium oxygen partial pressure (P O 2 ) for the HfB 2 (s) to HfO 2 (s) plus B 2 O 3 (l) and the partial pressures of B-O vapor species formed due to B 2 O 3 (l) volatilization increase with increasing temperature. Vapor pressures of the predominant gaseous species also increase with P O 2 . At 1000 K, the predominant vapor transition sequence is predicted be BO(g) fi B 2 O 2 (g) fi B 2 O 3 (g) fi BO 2 (g) with increasing P O 2 , and the predominant gas is BO 2 (g) with a pressure of 1.27310 26 Pa under the condition of P O 2 = 20 kPa. At higher temperatures of 1500, 2000, and 2500 K, the system undergoes vapor transitions in the same sequence of B(g) fi BO(g) fi B 2 O 2 (g) fi B 2 O 3 (g) fi BO 2 (g). Under the same condition of P O 2 = 20 kPa, the predominant vapor species is B 2 O 3 (g) with pressures of 2.38, 4.49310 3 , and 3.55310 5 Pa, respectively. Volatilization of B 2 O 3 (l) may produce porous HfO 2 scale, which is consistent with the experimental observations of HfB 2 oxidation in air. The present volatility diagram of HfB 2 shows that HfB 2 exhibits oxidation behavior similar to ZrB 2 , and factors other than volatility of gaseous species affect the oxidation rate.

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“…10,11,12,13,14 With this resurgence in basic research, UHTC carbides and nitrides are getting attention, as new processing techniques make the fabrication of these materials easier.…”

Section: Introductionmentioning

confidence: 99%

Recent Developments in Ultra High Temperature Ceramics at NASA Ames

Johnson

Gasch²,

Lawson³

et al. 2009

16th AIAA/DLR/DGLR International Space Planes and Hypersonic Systems and Technologies Conference

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NASA Ames is pursuing a variety of approaches to modify and control the microstructure of UHTCs with the goal of improving fracture toughness, oxidation resistance and controlling thermal conductivity. The overall goal is to produce materials that can perform reliably as sharp leading edges or nose tips in hypersonic reentry vehicles. Processing approaches include the use of preceramic polymers as the SiC source (as opposed to powder techniques), the addition of third phases to control grain growth and oxidation, and the use of processing techniques to produce high purity materials. Both hot pressing and field assisted sintering have been used to make UHTCs. Characterization of the mechanical and thermal properties of these materials is ongoing, as is arcjet testing to evaluate performance under simulated reentry conditions. The preceramic polymer approach has generated a microstructure in which elongated SiC grains grow in the form of an in-situ composite. This microstructure has the advantage of improving fracture toughness while

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Oxidation of Hafnium Carbide in the Temperature Range 1400° to 2060°C

Cited by 123 publications

References 13 publications

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Thermodynamic Calculation of HfB2 Volatility Diagram

Recent Developments in Ultra High Temperature Ceramics at NASA Ames

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