Abstract
In this paper, the rapid cooling thermal shock behaviors of ZrB2–SiC ceramics were measured using traditional water quenching method, and the rapid heating thermal shock behaviors of ZrB2–SiC ceramics were investigated using a novel in situ testing method. The measured critical thermal shock temperature difference for rapid cooling thermal shock was 373.6 °C; however, the critical thermal shock temperature difference for rapid heating thermal shock of ZrB2–SiC ceramics was measured to be as high as 1497.2 °C. The thermal stress distribution states after rapid cooling thermal shock and rapid heating thermal shock testing were analyzed using finite element analysis (FEA) method. The FEA results showed that there is a tensile stress existed on the surface for rapid cooling thermal shock, whereas there is a compressive stress existed on the surface for rapid heating thermal shock. The difference of thermal stress distribution resulted in the difference of the critical temperature difference for rapid cooling thermal shock and rapid heating thermal shock.
Highlights
Ultra high temperature ceramics (UHTCs) are promising candidates for use in thermal protection systems (TPS) and propulsion systems in hypersonic aerospace vehicles, owing to their ultra high melting temperatures, outstanding oxidation resistance, good chemical inertness, and high dimensional stability [1,2,3,4]
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 quenched into a water bath
The rapid cooling thermal shock behaviors of UHTCs were studied using a water quenching method, and the rapid heating thermal shock behaviors of ZrB2–SiC ceramics were investigated using a novel in situ testing method
Summary
Ultra high temperature ceramics (UHTCs) are promising candidates for use in thermal protection systems (TPS) and propulsion systems in hypersonic aerospace vehicles, owing to their ultra high melting temperatures, outstanding oxidation resistance, good chemical inertness, and high dimensional stability [1,2,3,4]. During the causative processes of UHTCs used in ultra high temperature applications, thermal shock occurs under rapid heating conditions, e.g., nosecones and sharp leading edges of hypersonic aerospace vehicles endure a server rapid aerodynamic heating in a short time during their flight [17,18,19], and the intense ascending thermal shock will lead to their failure. It is very important and necessary to investigate the rapid cooling thermal shock behaviors, and the rapid heating thermal shock behaviors of UHTCs
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