High-powered 83-GHz millimeter-wave beam sintering and heat treating of engineered ceramics in controlled atmospheres

Summary form only given. An experimental facility based on an 83-GHz, 15 kW CW industrial gyrotron has been set up at the Naval Research Laboratory to investigate novel mm-wave-beam-based approaches to processing ceramic materials, including sintering, coating, and joining applications. Current experimental and theoretical studies are investigating the sintering and heat-treating of advanced engineered ceramics such as ferrites, rare-earth magnet materials and laser hosts. Sintering and heat-treating of these materials requires stringent atmospheric and environmental control, including high vacuum, inert or reducing atmospheres or precise levels of oxygen partial pressure. Past work has described initial results using a large, 1 m/sup 3/ chamber. In order to more adequately control the processing conditions, a small, specialized chamber has been devised to fit within the large chamber. This specialized chamber has a variety of gas and electrical feedthroughs as well as a tuned window for RF transmission and visual monitoring. In this paper, the results of current experiments will be described. In particular, the results from the processing of nanopowder derived ferrites; rare-earth magnet materials and laser host materials will be presented.