致密非晶 SiCN 低压热稳定性及高温导电行为

Accurately quantifying the aerodynamic heating of high-temperature components of a hypersonic vehicle help develop the thermal protection system design and improve the reliability of the high-temperature components. In this paper，the feasibility about high temperature sensing of amorphous SiCN in the hypersonic aircraft field is discussed by studying the thermal stability and high-temperature electrical conductivity of dense amorphous SiCN under low pressure environment. The results show that the dense amorphous SiCN exhibits lower high temperature stability and anti-crystallization ability under low pressure environment. The visible crystallization and thermal decomposition occur at 1 300 ℃，which is about 200 ℃ lower than that of amorphous SiCN treated at normal pressure. The low pressure promotes the ordering transformation of free carbon. The resistance of amorphous SiCN treated at low pressure and 1 000 ℃ is about 4 orders of magnitude lower than that of amorphous SiCN treated at normal pressure，showing lower temperature sensitivity. In conclusion，amorphous SiCN still maintains excellent temperature sensing ability under low pressure environment，but the operating temperature has dropped by about 200 ℃.