Patent ID: 11919824
Assignee: SHANDONG LABORATORY OF YANTAI ADVANCED MATERIALS AND GREEN MANUFACTURING
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A silicon nitride ceramic sintered body, comprising
a sintered bulk; and
a hard surface layer having a thickness of 10-1000 μm, formed on a surface of the sintered bulk,
wherein the sintered bulk comprises a first silicon nitride crystalline phase and a first grain boundary phase, and the hard surface layer comprises a second silicon nitride crystalline phase and a second grain boundary phase,
wherein the first grain boundary phase comprises a metal tungsten phase, the metal tungsten phase being tungsten elementary substance and/or a tungsten alloy;
wherein the second grain boundary phase comprises tungsten carbide particles;

wherein tungsten element in the metal tungsten phase accounts for 80-100 wt % of total tungsten element in the first grain boundary phase; and
wherein tungsten element in the tungsten carbide particles accounts for 60-100 wt % of total tungsten element in the second grain boundary phase,
wherein the silicon nitride ceramic sintered body is prepared by a method comprising steps of
burying a tungsten toughened silicon nitride ceramic sintered body in a burying powder; and
subjecting the tungsten toughened silicon nitride ceramic sintered body to a heat treatment for a carbonization reaction, to obtain the silicon nitride ceramic sintered body,
wherein the burying powder comprises a carbon source; and
the heat treatment is performed at a temperature of 1100-1450° C. for 0.5-5 h;
wherein the tungsten toughened silicon nitride ceramic sintered body is prepared by a process comprising steps of
mixing and ball milling a silicon nitride source, a metal tungsten grain boundary phase precursor, and a sintering assistant, to obtain a mixed powder, the metal tungsten grain boundary phase precursor being at least one selected from the group consisting of tungsten elementary substance, and a tungsten alloy; and
forming the mixed powder into a preform, and sintering the preform in a nitrogen atmosphere, to obtain the tungsten toughened silicon nitride ceramic sintered body,

wherein the sintering is performed at a temperature of 1600-1900° C. and at a nitrogen pressure of not less than 0.3 MPa.