Research On Preparation Of Ti（C,N）/Al₂O₃Composite Powder And Its Sintering Properties By Reaction Milling

Ti（C,N）/Al₂O₃composite powders were prepared by high-energy ball milling usingrutile, aluminum, graphite and urea as the raw materials. The influence of raw materialratio, ball-to-powder ratio and milling time for the reaction were investigated. Throughorthogonal experiment of three elements and levels, the degree of significance was judgedaccording to the formation of Ti（C,N） the integral relative strength of the diffraction peaks.The characterization of phase formation, particles morphology and microstructures werecarried out by X-ray diffraction （XRD）, scanning electron microscopy （SEM） andtransmission electron microscopy （TEM）. Differential scanning calorimetry （DSC） wasused to analyze the reaction mechanism and energy change of the ball milling. TheTi（C,N）/Al₂O₃composite powders with raw material ratio C:N=0.9:0.1, ball-to-powderratio20:1, milling40h were sintered by hot-pressing sintering. The properties of thesintered samples with different sintering temperatures, soaking times and sinteringpressures, mechanical properties were measured.30wt%Ti（C,N）-70wt%Al₂O₃compositepowders were prepared by adding micron alumina. The sintered samples were obtained byvaccum hot-pressing sintering with different temperatures, and mechanical properties weremeasured.The results showed that raw material ratio was the significant element of the ballmilling reaction. Ti（C,N）/Al₂O₃composite powders were synthesized successfully withraw material ratio C:N=0.9:0.1, ball-to-powder ratio20:1and milling40h. Compositepowder particles distributed uniformly, and size ranged form300to500nm. Byimproving sintering temperature, prolonging soaking time and increasing sinteringpressure, the density and microhardness were increased. Grains were fine at highersintering temperature and by shorter soaking time, when the strength of materials wasimproved. The sintered samples were obtained at1500℃under30MPa with soakingtime of1h with well mechanical properties. The density, microhardness, fracturetoughness and bending strength were3.869g/cm3,1055Hv,9.71MPa·m1/2and325MParespectively.