超细硬质合金烧结过程中WC扩散-溶解-析出特征与机理研究

以08型WC与Co制成WC-10%Co试样条,脱蜡后分别于1 200﹑1 250﹑1 300﹑1 350℃进行烧结并分别保温1 h和5 h。采用扫描电镜观察烧结过程中WC晶粒形貌的变化,采用差热分析仪研究WC-10%Co的共晶温度。研究结果表明:WC-10%Co在低于共晶温度的烧结过程中发生了WC晶粒形貌由等轴形向棱边平直的多边形变化,并随着温度升高,晶粒尺寸增大。这表明在固相烧结时超细WC与钴相存在溶解析出过程,改变WC晶粒形貌并使晶粒长大。

Research of Characteristics and Mechanism on WC Grain Diffusion-Dissolution-Precipitation during Sintering of Ultrafine Cemented Carbide

After wet grinding of 08 grade tungsten carbide and cobalt powders, the mixtures were pressed into WC- 10%Co samples. The samples were dewaxed and sintered at 1 200, 1 250, 1 300 and 1 350 ℃ with soaking time of 1 h and 5 h, respectively. The WC grain morphology and its evolution were observed by scanning electron microscopy. The eutectic temperature of WC-10%Co was determined by differential thermal analyzer. The results show that, in the singtering process of below eutectic temperature, the shape of WC grain changes from equiaxed to edge straight polygonal, and the WC grain size grows up with the increasing of temperature. This indicates that during solid phase sintering diffusion---dissolution- precipitation existsd between ultrafine WC and Co phases changes the shape of WC grain and makes WC grains grow up.