ФОРМУВАННЯ СТРУКТУРИ ТА ПІДВИЩЕННЯ МЕХАНІЧНИХ ВЛАСТИВОСТЕЙ КЕРАМІЧНИХ МАТЕРІАЛІВ НА ОСНОВІ НІТРИДУ КРЕМНІЮ ПРИ ВИСОКОТЕМПЕРАТУРНОМУ ДЕФОРМУВАННІ
The change of structure and properties of sintered materials Si 3N 4-5mas.%Y 2O 3-2mas.%Al 2O 3, Si 3N 4-5mas.%Y 2O 3-5mas.%Al 2O 3, at deformation on direct extrusion with degree of wringing 55 and 72 % within the temperature range 1750-1850 0С and pressures 20-30 MPa was investigated. After high temperature extrusion a structure from oriented along direction of deformation elongated grains of b - Si 3N 4 is formed. The fracture toughness of obtained anisotropic structure in the directions perpendicular and parallel to direction of extrusion were at a rate of 11,5-12,0 MPа·m 1/2 and 7,5-7,8 MPа·m 1/2 accordingly. Hardness after extrusion increases on 1,0 GPa and it is at level 16,0 GPa. Keywords: silicon nitride, extrusion, microstructure, anisotropy, hardness, fracture toughness.