Silicon Nitride Based Ceramic Tubes for Gun Barrel Applications

There is a need to replace steel gun barrels, both to improve lifetime and reduce weight. Ceramic liners are obvious candidates due to their high wear and corrosion resistance, as well as high temperature capabilities, and Si3N4 is a preferred material. However, Si3N4 tubes greater that 200mm in length cannot be fabricated to the required tolerances due to bowing during processing. It is proposed that this problem be addressed by combining developed green body fabrication processes as practiced commercially by SiNeramics with the patented continuous sintering process of Dr. Dale E. Wittmer, Wittmer Consultants, Inc. (WCI). This sintering has already been demonstrated to be enabling in terms of producing ceramic bodies that maintain dimensional integrity over significant lengths. Two Si3N4-based compositions will be explored: (1) a cost effective, commercial one that has excellent properties, and (2) a typical one where oxide additives, incorporated as coatings, will be used to improve uniformity of the green body and minimize density gradients. The combined extensive advanced gun barrel material development experience of MER with SiNeramics and WCI’s expertise ensures high potential for the successful development of SiN4 tubes for gun barrel applications.