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 of Uniformity and Plate-like Morphology Abnormal Growth of WC Grain in Cemented Carbide

针对矿用硬质合金对微观结构均匀性的要求,以WC-Co硬质合金为研究对象,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,制备了14组合金试样,通过对烧结后合金的微观结构观察,分析研究了以上因素对WC晶粒均匀性的影响。其中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。研究结果表明:球磨过程中产生的细小WC数量越多,越易于出现板状晶;硬质合金中板状晶的出现与钴含量、烧结温度、抑制剂、球磨时间、WC原始粒度都有密切关系;WC粒度增加、钴含量降低、球磨时间减少、烧结温度降低和添加抑制剂均可提高WC晶粒的均匀性并降低合金中出现板状晶的可能性。

In order to satisfy the requirement of the microstructure uniformity for cemented carbide, through observing the microstructure of sintered alloy, 14 groups of alloy samples were prepared for studying the effects of some factors, such as WC powder, ball milling process, cobalt content, carbon content, additive and sintering temperature, on the WC grain uniformity, and the effects of these factors on the uniformity of the alloy were investigated. The reasons to cause abnormal growth of WC grain with plate-like morphology were analyzed. The results show that much more plate-like WC grain appears with the increasing amount of fine WC grains brought during the ball milling process. The plate-like WC grain growth in the cemented carbide is closely connected with cobalt content, sintering temperature, inhibitor, milling time and original WC particle size. The uniformity of WC grain in the cemented carbide can be improved by increasing WC particle size, decreasing milling time, reducing sintering temperature and adding additive, and the probability of WC plate-like grains growth can be reduced.