Arc-Jet Testing of Ultra-High-Temperature-Ceramics

Abstract

The article deals with arc-jet experiments on different Ultra High Temperature Ceramics models in high enthalpy hypersonic non equilibrium flow. Typical geometries for nose tip or wing leading edges of interest for hypersonic vehicles, as rounded wedge, hemisphere and cone are considered. Temperature measurements have been performed using pyrometers, an IR thermocamera and thermocouples. Spectral emissivity has been evaluated by suitable experimental techniques. The details of the experimental set-up, the tests procedure and the measurements are discussed in the text. The UHTC materials have been tested for several minutes to temperatures up to 2050 K showing a good resistance in extreme conditions. Fundamental differences between the various model shapes have been analysed and discussed. Numerical-experimental correlations have been carried out by a CFD code, resulting in good agreement with proper modelling. The numerical rebuilding also allowed to evaluate the catalytic efficiency and the emissivity of the materials at different temperature.

Oxidation Behavior of Aerospace Materials in High Enthalpy Flows Using an Oxyacetylene Torch Facility

“…Leading edges for proposed hypersonic vehicles (>Mach 5) will experience extreme aerothermal heating (>2000°C), high enthalpy gas (>4 MJ/kg), high pressures (43 kPa), and high heat flux (1000 W/cm 2 ) within a reactive gas stream from partially or fully dissociated air . Currently, no single land based test facility is capable of duplicating all aspects of the extreme hypersonic flight environment, as summarized in Table , nor do they possess the necessary diagnostic equipment to study fundamental material responses .…”

“…In doing so, we characterize the free‐stream flame environment for heat flux (~100–800 W/cm 2 ), gas velocity (<200 m/s) using particle tracking velocimetry (PTV) method, and oxygen content (~1–12 kPa). Thus, our critical analysis results in a free‐stream flame with a calculated gas enthalpy greater than 40 MJ/kg which is considered high enthalpy flow and allows for low cost infrastructure and rapid and high throughput testing. Therefore, we propose that the oxyacetylene torch facility can be used as a reliable screening test for aerospace materials exposed to extreme environments once free‐stream flame conditions are well characterized and relationships between flame chemistry and the resulting flame environment are understood.…”

Synthesis, Characterization, and Microstructure of ZrC/SiC Composite Ceramics via Liquid Precursor Conversion Method

“…Ultrahigh‐temperature ceramics (UHTCs) have gained considerable interest for their aerospace applications in extreme environments, and refractory metal carbides and borides are promising candidates for UHTCs . Zirconium carbide (ZrC) exhibits exceptional properties, such as high melting point (~3550°C), high hardness, high strength, solid‐state phase stability, and good thermal shock resistance, etc .…”

Synthesis & Fundamental Formation Mechanism Study of High Temperature & Ultrahigh Temperature Ceramics

“…Transition metal carbides and borides of groups IV and V are both considered as UHTCs [1][2][3][4]. These ceramics have a unique combination of properties such as high hardness, high melting point, high electrical and thermal conductivity, which makes them promising materials for cutting tools and ultrahigh temperature applications such as critical parts for engines and hypersonic vehicles that may need to tolerate temperatures even above 2000 °C [5][6][7][8][9][10]. However, it has been noticed that conventional binary UHTCs are not sufficient for the oxidizing and rapid heating environments [9,10].…”

“…Among transition metal carbide UHTCs, hafnium carbide (HfC, T m =3900°C) and tantalum carbide (TaC, T m =3985°C) are of particular interest due to their very high melting points, high hardness (TaC: ~19GPa and HfC: ~20GPa), high electrical and 2 thermal conductivity [1,2,[5][6][7][8][9][10]. However, these properties could improve further through forming solid solutions and/or composites.…”