THE INFLUENCE OF PRECERAMIC BINDERS ON THE MICROSTRUCTURAL DEVELOPMENT OF SILICON-NITRIDE

A number of polymeric precursors to silicon nitride were prepared and evaluated as binders in cold pressing/pressureless sintering operation s. These polymers exhibited ceramic yields in excess of 75% by weight, and powder compacts made using them as binders displayed improved gre en handling properties. Compacts pyrolysed at 800 degrees C exhibited unusual microstructures, including the developing of whiskers in situ. Based on microstructural observation, compacts sintered under pressur eless conditions appeared to show enhanced densification relative to t hose processed without preceramic binders. Preceramic binders appeared to enhance the formation of beta-Si3N4 and may enhance densification of compacts sintered under pressureless conditions.