Alternative AlN based lossy ceramics for high power applications

Since the early 1980's, U.S. microwave tube industry has been using BeO-SiC lossy ceramic composite materials for microwave tube components. However, due to the toxicity of BeO during the production process (related to Chronic Beryllium Disease), U.S. currently does not have a BeO-SiC material supplier, and no other commercially available material has yet been qualified for these applications. This necessitated research and development of safe, alternate lossy materials that could replace BeO-40% SiC material, used by three major U.S. tube manufacturers. This paper presents material requirements and development results obtained for lossy materials based on AlN.