A A12O3 DISPERSION-STRENGTHENED Ti2AlN CERAMIC COMPOSITE MATERIAL AND ITS PREPARATION

摘要

The present invention relates to a A1<SUB>2</SUB>O<SUB>3</SUB> dispersion-strengthened Ti<SUB>2</SUB>AlN ceramic composite material, the matrix Ti<SUB>2</SUB>AlN and the reinforcing phase A1<SUB>2</SUB>O<SUB>3</SUB> are obtained by in-situ reaction. The amount of A1<SUB>2</SUB>O<SUB>3</SUB> is from 5 to 50% by volume, particle size distribution is 500nm-2µm, the average particle size is 0.8-1.2µm, the crystal particle Ti<SUB>2</SUB>AlN is in form of disk, the thickness of the said disk is about 80-120nm, and the length is 0.5-2µm. The composite material exhibits excellent high temperature deformation capacity under compression stress and flexural stress, excellent oxidation resistance over a long time (for example 100 hours) at 1100-1350° C, and specific resistance curve having metal characteristic. The specific resistance of the composite material at room temperature is 0.3-0.8µO.m. The present invention also relates to a method for preparing the said composite material. The method includes the following steps: providing a mixed gas containing gas containing nitrogen element, H<SUB>2</SUB> and Ar at 0.8-1.2atm, in which the amount of gas containing nitrogen element is about 0-20% by volume, the volume ratio of H<SUB>2</SUB> and Ar is 1:0.8-1.2, continuously providing Ti-Al alloy bar containing A1 in amount of 20-60% by atom, pure A1 bar and pure Ti bar, synthesising nanometre powder by HPMR, densifing the nanometre powder through thermal pressing in vaccum at temperature of 800-­1200 ° C, pressure of 40-60Mpa and vaccum of 2 X 10<SUP>-2</SUP>-5 X 10<SUP>-3</SUP>Pa for 4­-6h.