矿用硬质合金WC晶粒均匀性及板状形貌异常长大的控制

Control on uniformity and plate-like morphology abnormal growth of the WC grain in cemented carbide

WC晶粒均匀性控制是硬质合金制造中的一项重要问题。本文针对矿用硬质合金对微观结构均匀性的要求,研究了WC原料、球磨工艺、钴含量、碳含量、添加剂、烧结温度等因素对WC晶粒均匀性的影响,重点分析了硬质合金微观组织中WC晶粒呈板状形貌异常长大的原因。主要研究结果有两点:(1)增加WC原料的粒度,降低球磨时间能够显著地提高WC晶粒的均匀性;(2)WC晶粒板状形貌长大的主要原因是细小碳化钨在烧结过程中以粗大碳化钨晶粒为核心定向生长,减低细小碳化钨比例、减少烧结时液相体积、抑制烧结过程中的熔解-析出过程都可以明显减少WC板状晶出现的几率。

WC grain uniformity is an important issue for the manufacture of cemented carbide. In this paper,the effect of some factors on the WC grain uniformity is carried,such as WC powder,ball milling process,the cobalt content,carbon content,additive,sintering temperature. At the same time,the reasons to cause WC abnormal growth of platelike morphology are analysised. The main results are as follows ：（1） With increasing WC powder size and reducing the milling time,the uniformity of WC grain can significantly improve.（2） the main reason for WC grain plate morphology growth is that fine tungsten carbide growth on coarse tungsten carbide grains as the core in the sintering process,reduc-ing fine tungsten carbide proportion,reducing the sintering liquid volume,inhibiting the precipitation during sintering process can reduce the probability of WC plate-like grains growth.