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Title:: Major Advancement and Development Trends in Study of Hot-wall Microwave -transparency Mechanisms and High-temperature Microwave-transparent Materials

Author(s):: Li Zhongping; (Science and Technology on Advanced Functional Composite Materials, Aerospace Research Institute of Materials & Processing Technology, Beijing, 100076)

Abstract:: The background and physicsbasis of hotwall microwavetransparency problem are discussed in this paper. Major advancement is summarized in areas including behavior of ablation and heattransfer, thermodielectric behavior and hotwall microwavetransparency mechanism, hightemperature dielectric testing, simulation of hotwall microwavetransparency, and hightemperature microwavetransparent materials. Future development trends in related areas are presented. Hightemperature melt and dynamic diversification of solid/liquid/gas result in break of dielectric property for hotradome or antenna window, which is the main reason for the “blackout” of hypersonic aerospace vehicles. Silica, boron nitride and SiON material are melting ablation, evaporation ablation and melting/evaporation ablation materials respectively. The microwave transporting efficiency of boron nitride is directed by electron conducting loss, while the microwave transporting efficiency of silica is directed by ion conducting loss. Largescale, high precision, wide temperature range and wide frequency range are the main objective for next generation test and computation technology for hotwall transparent materials. Big size and Si(B)ON(M) based materials are the important trend for developing new hotwall transparent materials.