METHOD OF MAKING SiAlON BODIES, MATERIAL FOR FORMING SiAlON, AND SiAlON BODIES FORMED THEREFROM

摘要

A sinterable material for forming SiAlON ceramic material. The sinterable material is a powder mixture containing six elements: (a) silicon nitride, (b) aluminum nitride, (c) an oxide or nitride of a rare earth element, (d) an oxide or nitride of strontium, (e) an oxide or nitride of calcium, magnesium, lithium, or sodium, and (f) a non-alloying additive which is an oxide or nitride of zirconium, tantalum, gallium, hafnium, or indium, the non-alloying additive being present in an amount of at least about 0.3 weight percent based on the weight of the powder mixture. The sinterable material can be made into a ceramic body using a method of the present invention. The method includes three steps: making the powder mixture, forming the powder mixture into a greenware body, and sintering the greenware body at an elevated temperature to form the SiAlON ceramic body. The SiAlON ceramic body of the present invention contains a ceramic material which incorporates the non-alloying additive within the material at a level of at least about 0.3 weight percent. The ceramic body has at least an alpha-SiAlON phase and a beta-SiAlON phase which define an alpha-to-beta weight ratio. The alpha-to-beta weight ratio is in the range of from about 10:90 to about 90:10. Silicon carbide particulates can be incorporated into the powder mixture. Low-pressure or pressureless sintering can be used.