Effect of Powder Processing on Slip Casting Parameters and Sintering of Si3N4(-)Y2O3(-)SiO2

摘要

A procedure was developed for slip casting Si3N4(-)Y2O3(-)SiO2 compositions. Thesilicon nitride was oxidized to supply the silica. The procedure resulted in 65 w/o slips with viscosities of 35 mPa(dot)s which, when cast, yielded compacts which were 56% of theoretical density. Slips with 70 w/o solids loading were also prepared having viscosities of 120 mPa(dot)s. The properties of the slips were influenced by the starting silicon nitride powder, dispersant, and milling media.The resulting compacts could be gas pressure sintered to full density, at temperatures as low as 1850 deg C, using nitrogen pressures as low as 4 MPa. Strengths as high as 750 MPa were achieved and the initial results show good creep resistance at 1350 deg C. Silicon nitrides, Slip casting, Oxidation, Sintering, Dispersants, Silica.