高性能再生硬质合金的短流程回收制备

SHORT-TERM PROCESS OF RECYCLING CEMENTED CARBIDE SCRAPS AND PREPARATION OF HIGH PERFORMANCE HARD METALS

以WC-16%Co(质量分数)废旧硬质合金块体为原料,采用氧化-原位还原碳化的方法对其进行回收制备再生WC-16%Co复合粉,并对再生复合粉进行低压烧结制备再生硬质合金块体材料.通过热力学计算确定氧化物粉末和炭黑发生原位还原碳化反应的温度范围,采用实验方法系统研究了原料粉末中配C量对再生复合粉和再生硬质合金的物相组成、力学性能等的影响,并对再生合金的显微组织与性能的关系进行了分析.结果表明:随着原料粉中配C量的增加,再生复合粉中的Co6W6C相逐渐减少,总C和游离C含量增加;当配C量为16.60%时,可制备出化学成分符合原生WC-16%Co复合粉要求的再生复合粉,经低压烧结可得到物相纯净,断裂韧性达到23.05 MPa·m1/2,横向断裂强度达到4020 MPa的高性能再生硬质合金;再生硬质合金的Co相分布是否均匀,对再生硬质合金的综合性能优良与否起到至关重要的作用.

Recycling of cemented carbide scraps is drawing more and more attention to companies and countries all over the world. However, the recycling method has always been a problem where there are many fac- tors involved. The feasibility, recycling rate, energy consumption and the environment conservation are all signifi- cant factors for the recycling method that need to be considered. In this work, using the cemented carbides scraps as the raw material, the recycled WC-16%Co （mass fraction） composite powder was synthesized by oxidation, re- duction and carbonization reactions. Then the recycled composite powder was sintered to prepare the hard metal bulks by sinter-HIP （hot isostatic pressing）. The results indicate that with the carbon addition increases, the con- tent of Co6W6C in the composite powders decreases while the total carbon and free carbon increase. When the car- bon addition is 16.60%, the high-performance hard metal bulks can be obtained, with a fracture toughness of 23.05 MPa＇ m1＇2 and a transverse rupture strength of 4020 MPa. Moreover, the Co phase distributes more homogeneously in the recycled hard metals. The larger mean free path of the Co phase and the lower contiguity degree of the WC grains lead to the high performance of the recycled hard metal materials.