原始WC粉末粒度分布及球磨时间对超细硬质合金微观结构的影响

Effects of Raw WC Powder Size Distribution and Milling Time on the Microstructure of Ultrafine Cemented Carbide

分别采用两种Fsss粒度相近、粒度分布差别很大的超细WC粉末为原料,经10～50 h球磨,制备WC-12%Co-1.0%(Cr3C2+VC)混合料,并在1 350、1 410℃和1 450℃下烧结,采用SEM研究两种合金的微观组织结构变化。研究结果表明:采用粒度分布窄的WC粉末为原料,经10 h球磨后烧结,合金中WC晶粒分散均匀,几乎没有WC晶粒粗聚体;而采用粒度分布宽、包含大量团聚体的WC粉末为原料,经10 h球磨、烧结后,合金中含有大量的粗大WC晶粒团聚体,随球磨时间增加,WC团聚体数量、单个团聚体中包含的WC晶粒数量急剧减少,团聚体尺寸不断减小,经50 h球磨才能得到微观结构较为均匀的合金;相同球磨时间下,随烧结温度从1 350℃升高到1 450℃,团聚体尺寸不断增加,团聚体内的形貌也发生明显变化。

The ultra-fine WC-12%Co-1.0%(Cr3 C2+VC)mixture was prepared,using two kinds of raw WC powders with similar Fsss and different particle size distributions.Two kinds of alloys were sintered at 1 350℃,1 410℃and 1 450℃after milling at different times,and the microstructure evolution of the alloys was investigated by SEM.The results show that the WC grains distributed uniformly and no coarse aggregates exist in the alloy using raw WC powder with narrow size distribution after 10 h milling and sintering.The WC-12%Co-1.0%(Cr3 C2+VC)alloy contains a large number of aggregates after 10 h ball milling and sintering,using WC powder with wide size distribution and a large number of aggregates as raw materials.With the increase of milling time,the number of aggregates and WC grains contained in a single aggregate decrease sharply,while the aggregate size decreases continuously.The microstructure of the alloy with uniform microstructure can be obtained by 50 h ball milling.At the same milling time,the agglomerate size increases with the increase of sintering temperature from 1 350℃to 1 450℃,and the morphology of aggregates also change significantly.