自蔓延离心熔铸TiB2-(Ti,W)C-TiC陶瓷研究

基于离心热爆反应、难熔液相分离与快速凝固原理,选取(WO3+Al+C)体系辅助(B4C+Ti)反应体系,采用自蔓延离心熔铸工艺可以成功制备出TiB2微纳米晶补强TiC-(Ti,W)C陶瓷基复合材料.将(B4C+Ti)、(WO3+Al+C)两种反应体系依次装填入坩埚中进行SHS离心熔铸实验,发现因W-Ti-C液相动力学粘度的降低、Al2O3液滴迁移路程减小,极大促进Al2O3液滴的Stokes上浮过程,故而显著减小残存于陶瓷基体上的氧化物夹杂含量与尺寸,进而TiB2微纳米片晶诱发的强烈自增韧机制与Al2O3微纳米晶产生的残余应力增韧效应,使得TiB2-(Ti,W)C-TiC陶瓷的弯曲强度、断裂韧性与维氏硬度分别达到(952±25)MPa、(12.6±2.5)MPa·m1/2与(28.6±1.2)GPa.

TiB2 ( Ti,W) C-TiC Composite Ceramics Prepared by SHS Centrifugal Casting

Based on principle of centrifugal thermal explosion reaction , refractory liquid phase separation and rapid solidification , the micro/nanograined TiB2 reinforced ( Ti,W) C-TiC composite ceramics were successfully prepared by using the reaction systems of ( WO3 +Al+C) and ( B4C+Ti) through the self propagating centrifugal casting technology .The results of experiments after adjusting powder ball -milling, filling mode showed that the Stokes floating process of Al2O3 droplets was greatly promoted due to the decrease of the dynamic viscosity of W-Ti-C liquid phase and the decrease of the migration distance of Al2O3 droplets.As a result, the content and size of Al2O3 inclusions were both reduced greatly in ceramic matrix.Furthermore, because of the synergistic effect of the strong self toughening mechanism induced by TiB2 micro nano lamellae and residual stress toughening effect produced by Al2O3 micro nanocrystals , the bending strength , fracture toughness and Vickers hardness of TiB2-( Ti,W) C-TiC ceramics were (952+25) MPa, (12.6+2.5) MPa/m1/2 and (28.6+1.2) GPa respectively.