INFLUENCE OF GRANULE CHARACTER AND COMPACTION ON THE MECHANICAL-PROPERTIES OF SINTERED SILICON-NITRIDE

The influence of granule character and compaction on the mechanical pr operties of sintered silicon nitride was studied as a function of the pH of the spray-dry slurry. The character and the compaction behavior of the spray-dried silicon nitride granules considerably affect the me chanical properties of the sintered body. Dense and hard granules resu lting from a well-dispersed slurry retained their shape in green compa cts and caused numerous pore defects in sintered body. Decreasing the slurry pH to a certain value (e.g., 7.9) caused slurry flocculation an d reduced the granule density as well as the diametral compression str ength of the granules. Sintered bodies fabricated with these weak gran ules contained fewer defects and showed remarkable strength increase.