Optical Emission Spectroscopy During Plasmatron Testing of ZrB2-SiC Ultrahigh-Temperature Ceramic Composites

Playez, M.; Fletcher, Douglas G.; Marschall, Jochen; Fahrenholtz, William G.; Hilmas, Greg; Zhu, Shujia

doi:10.2514/1.39974

Cited by 26 publications

(8 citation statements)

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“…Oxygen reactions result in a larger oxide scale for the DNE‐TGA specimen as compared to the conventional specimen [Figs. (c) and (d)]; therefore, we conclude that oxygen has diffused farther into the DNE‐TGA specimen likely through grain boundaries, as reported by others . To determine how the oxide scale grows and changes composition during the isothermal period using DNE‐TGA, specimen cross sections are examined at 0, 8, and 15 min as shown in Figs.…”

Section: Resultssupporting

confidence: 55%

High‐Temperature Isothermal Oxidation of Ultra‐High Temperature Ceramics Using Thermal Gravimetric Analysis

Miller-Oana

Corral

2015

J. Am. Ceram. Soc.

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Oxidation of ZrB 2 + SiC composites is investigated using isothermal measurements to study the effects of temperature, time, and gas flow on oxidation behavior and microstructural evolution. A test method called dynamic nonequilibrium thermal gravimetric analysis (DNE-TGA), which eliminates oxidation during the heating ramp, has been developed to monitor mass change from the onset of an isothermal hold period (15 min) as a function temperature (1000°C-1600°C) and gas flow (50 and 200 mL/min). In comparing isothermal to nonisothermal TGA measurements, the scale thicknesses from isothermal tests are up to 4 times greater, indicating that oxidation kinetics are faster for isothermal testing, where the oxide scale thickness is 110 lm after 15 min at 1600°C in air. Isothermal oxidation followed parabolic kinetics with a mass gain that is temperature dependent from 1000°C-1600°C. The mass gain increased from~5 to 45 g/m 2 and parabolic rate constants increased from 0.037 to 2.2 g 2 /m4 Ás over this temperature range. The effect of flow velocity on oxidation is not significant under the given laminar flow environment where the gas boundary layer is calculated to be 4 mm. These values are consistent with diffusion of oxygen through the glass-ceramic surface layer as rate limiting.

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Section: Resultssupporting

confidence: 55%

High‐Temperature Isothermal Oxidation of Ultra‐High Temperature Ceramics Using Thermal Gravimetric Analysis

Miller-Oana

Corral

2015

J. Am. Ceram. Soc.

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“…A further possible benefit of transpiration cooled heat shields is the mitigation of surface oxidation. The practical temperature limit of both C/C and UHTC is determined by the onset of surface oxidation, which starts to occur at higher wall temperatures and prevents the re-usability of heat shields or can even lead to a catastrophic failure [22,59,64,65].…”

Section: A Steady State Flight Analysismentioning

confidence: 99%

Performance of Transpiration-Cooled Heat Shields for Reentry Vehicles

2020

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This paper presents results of a system study of transpiration cooled thermal protection systems for Earth re-entry. The cooling performance for sustained hypersonic flight and transient re-entry of a blunt cone geometry is assessed. A simplified numerical model is used to calculate the transient temperature of a transpiration cooled heat shield. The performance of transpiration cooling is assessed by calculating the overall required coolant mass for different steady state and transient flight scenarios. Spatially and temporally optimised mass injection is presented for various flight conditions. The majority of the injection is required on the spherical nose segment of the blunted cone. Carbon/Carbon composite ceramic and the ultra high temperature ceramic Zirconium diboride are considered as wall materials. Both materials require similar amounts of coolant injection. In continuous hypersonic cruise, transpiration cooling is highly effective for flight conditions with velocities below 8 km s −1 and altitudes above 40 km. For transient re-entry, transpiration cooling is most viable for trajectories of entry velocities below 8.5 km s −1 and ballistic coefficients below 2.1 kg m −2. Nomenclature A Area, m 2 C D Drag coefficient c p Specific heat capacity, J kg −1 K −1

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“…Such test environments are provided by arc-jet or inductively coupled plasma (ICP) wind tunnels which expose test articles to high-enthalpy reactive gas flows. Tests of UHTC materials in arc-jet facilities have been reported in the scientific literature by Kaufman, 3 Metcalfe et al, 8 Wuchina and Opeka, 9 Opila et al, 10 Gasch et al, 11 Chamberlain et al, 12 Savino et al, 13 Monteverde and Savino, 14 and Zhang et al 15 Tests of UHTC materials in ICP facilities have been reported by Ito et al, 16 Marschall et al, 17 and Playez et al 18 In this paper we discuss the test environments provided by these two types of plasma wind tunnel facilities. We highlight the coupling between the high-enthalpy reactive flow stream and the test specimen in determining UHTC material response to these environments.…”

Section: Introductionmentioning

confidence: 90%

High-enthalpy test environments, flow modeling and in situ diagnostics for characterizing ultra-high temperature ceramics

Marschall

Fletcher

2010

Journal of the European Ceramic Society

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Optical Emission Spectroscopy During Plasmatron Testing of ZrB2-SiC Ultrahigh-Temperature Ceramic Composites

Cited by 26 publications

References 26 publications

High‐Temperature Isothermal Oxidation of Ultra‐High Temperature Ceramics Using Thermal Gravimetric Analysis

High‐Temperature Isothermal Oxidation of Ultra‐High Temperature Ceramics Using Thermal Gravimetric Analysis

Performance of Transpiration-Cooled Heat Shields for Reentry Vehicles

High-enthalpy test environments, flow modeling and in situ diagnostics for characterizing ultra-high temperature ceramics

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