MTL TR 90-6 AD-A220 428 A FRACTURE MECHANISM MAPS FOR ADVANCED STRUCTURAL CERAMICS PART 1: METHODOLOGY AND HOT-PRESSED SILICON NITRIDE RESULTS GEORGE D. QUINN CERAMICS RESEARCH BRANCH February 1990 Approved for public release; distribution unlimited. LADORTOY ComMAD U.S. ARMY MATERIALS TECHNOLOGY LABORATORY WIM "l~ y m""TA W~trown, Musuadusett 02172-0001 90 04 12 1 '