2Hf 2O 7 coating under an oxyacetylene torch]]>

摘要

Y2Hf2O7possesses low thermal conductivity and high melting point, which make it promising for a new anti-ablation material. For evaluating the thermal stability and the potential applications of Y2Hf2O7on anti-ablation protection of C/C composites, Y2Hf2O7ceramic powder was synthesized by solution combustion method and Y2Hf2O7coating was prepared on the surface of SiC coated C/C composites using SAPS. Results shown that the coating exhibits good ablation resistance under the heat flux of 2.4?MW/m2with the linear and mass ablation rates are 0.16?μm?s?1and ?0.028?mg?s?1, respectively, after ablation for 40?s. With the prolonging of the ablation time, the increasing thermal stress causes the increase of cracks. Moreover, the chemical erosion from SiO2and the physical volatilization of low temperature molten products aggravate failure of the Y2Hf2O7coating.