Dimensional Change Characteristics of Ceramics Produced by Simultaneous Nitriding of Si and Ti Powders and its Application to Adiabatic Engine Parts

Abstract

The study was conducted about dimensional change and the microstructure of material (RBSTN) produced by using Si and Ti mixture as staring powders. And also adiabatic piston head was fabricated as a trial using the material. The results were summarized as follows.(1) The dimensional change ratio increased as a function of the amount of Ti powder with a change from shrinkage to expansion at about 12wt% of Ti. And it was clearly shown that expansion of 1.3% occurred during sintering for compacts of Si(70wt%) and Ti(30wt%) mixture powders. On the contrary, shrinkage of 0.08% occurred when only Si was used as a starting powder.(2) The dimensional change ratio during dewaxing and sintering were plus and constant, almost independent of the packing density in green body.(3) In sintered body, TiN0.9 and small amount of TiO2 in a and β-Si3N4 as matrix, were formed.(4) Almost no gap was found at the boundary of SSN frame and porous ceramics (RBSTN) inside due to the small expansion of it during sintering. And partially they were bonded.(5) Al, originally one of the elements of SSN, diffused into porous ceramics, which suggested that it might work for bonding SSN and RBSTN.