EVALUATION OF SILICON-NITRIDE AS AN ADVANCED RADOME MATERIAL

Various forms of silicon nitride (Si3N4) are investigated to determine their suitability as radome materials for hypersonic, radar-guided missiles. The Applied Physics Laboratory has directed test efforts to assess the performance of these materials for use in radome manufacture. A database of thermal transport and mechanical properties has been generated by the developers of these materials and by other independent laboratories. The Laboratory suggested standard surface-finish techniques and a uniform sample size and shape for use by all suppliers so that direct comparisons could be made. The results of tests conducted from 1985 to 1988 on mechanical strength and particle impact damage are presented along with an explanation of the methods for obtaining reliable strength and toughness values essential for radome design.