Thermal and Oxidation Response of UHTC Leading Edge Samples Exposed to Simulated Hypersonic Flight Conditions

Abstract

Sharp leading edge (LE) samples of UHTC (20 vol%SiC–HfB2) and SiC were exposed to simulated hypersonic flight conditions using a direct‐connect scramjet rig and their thermal and oxidation responses measured. The measured back‐wall temperatures and scale thicknesses were significantly smaller than might be expected from stagnation temperatures at the LE. Furthermore, the scale that formed around the LE was more uniform than expected from the steep drop in cold wall heat flux with distance from the tip. These results were interpreted and rationalized using physics‐based models. An aerothermal model in combination with an oxidation model accounted for the observed scale thicknesses at the tip and their slight variation with distance. The scale thicknesses were similar to values reported for exposures in furnaces at temperatures calculated for the tip, but less than those reported in arc jet tests. The formation of hafnon (HfSiO4) and the absence of external glassy layer and of silica in the outer portions of the oxide region are unique to scramjet tested samples, presumably due to the high fluid flow (high shear and evaporation) rates.

Rapid heating thermal shock study of ultra high temperature ceramics using an in situ testing method

“…However, their intrinsic characteristics, such as low fracture toughness (premature failure due to brittle fracture) [5][6][7], poor thermal shock resistance [8][9][10], are still obstacles for them to be used widely, especially for applications with high heat transfer and/or rapid environmental temperature changes. Therefore, the thermal shock behaviors of UHTCs have been intensively investigated in past decades [11][12][13][14], and how to improve the thermal shock resistance of UHTCs is one of the main challenges for engineering application.…”

“…Usually, the thermal shock of UHTCs has two conditions: rapid cooling thermal shock and rapid heating thermal shock. At present, almost all experimental reports of UHTCs are about their rapid  cooling thermal shock behaviors [11][12][13][14]. The rapid cooling thermal shock behaviors of UHTCs are always evaluated by water quenching method, in which the ceramic specimens are heated to a particular temperature and then quenched into a water bath.…”

“…The rapid cooling thermal shock behaviors are commonly tested using water quenching method, and the residual strengths are subsequently measured after quenching [11][12][13][14]. Nevertheless, testing methods for the rapid heating thermal shock behaviors mainly include laser heating [20], electron beam heating [21], oxyacetylene heating [18], radiant heating [22], plasma arc heating [23], arc-heating wind tunnel heating [17,24], etc.…”

Fabrication and heat transfer characteristics of C/SiC pyramidal core lattice sandwich panel

“…Reusable launch vehicle (RLV) and hypersonic vehicle have been extensively studied in the past decades [1]. It is found that one of the most important issues is the thermal protection system (TPS).…”

Theoretical investigations on mechanical and thermal properties of MSiO4 (M = Zr, Hf)

“…20,21 Moreover, recently reported experiments revealed that MSiO 4 are the main constitutions of oxidation products of Zr-and Hf-based ultrahigh temperature ceramics, especially under low oxygen partial pressure and simulated hypersonic flight conditions. 22,23 The presence of high content of zircon phase could improve the oxidation resistance of the matrix.…”