铈与YG6硬质合金制备过程中富钙相的交互作用

Interaction of cerium and calcium-enriched phase in the preparation process of YG6 cemented carbide

在硬质合金的原材料仲钨酸铵(APT)粉末中添加Ca和稀土Ce元素,探讨稀土Ce元素与硬质合金制备过程中富钙相的交互作用。材料的物相组成、显微结构及成分分别通过X射线衍射仪、扫描电子显微镜及能谱进行检测与分析。结果表明:氧化钨还原过程中会产生CaWO_4和Ca_(4.26)W_(10)O_(30)两种富钙相,分布在钨颗粒内部和周围,使钨颗粒的棱角钝化,碳化后富钙相转变为Ca_(4.26)W_(10)O_(30)和CaC_2相,富钙相可急剧降低YG6硬质合金的性能;添加适量稀土Ce可降低富钙相对钨粉的影响,钨粉颗粒的棱角变得明显,颗粒尺寸变小且分布均匀,稀土Ce与富钙相发生反应生成Ce_(0.9)Ca_(0.1)O_(1.9)三元相;稀土Ce与富钙相的交互作用效果显著,与1%Ca-YG6硬质合金相比,1%Ce+1%Ca-YG6硬质合金的致密度、硬度和断裂韧性分别提高了7.8%,34.3%和67.8%。

The elements of Ca and rare earth Ce were added in APT powder. The interaction of rare earth element Ce with calcium-enriched phase was discussed during the preparation process of cemented carbide. The phase composition, microstructure and element distribution were tested by using X-ray diffractometer, scanning electron microscope and energy disperse spectroscopy, respectively. The results show that two kinds of calcium-enriched phases, CaWO4 and Ca4.26W10O30, are generated in the process of reducing tungsten oxide, which passivate tungsten particles. After carburization, calcium-enriched phases transform into the Ca4.26W10O30 and CaC2 phases. Calcium-enriched phases can sharply reduce the property of YG6 cemented carbide. Adding a moderate amount of rare earth Ce can decrease the influence of calcium-enriched phases on tungsten particles. The edges and corners of tungsten particles become more obvious, and the particle size of tungsten powders becomes smaller and uniform. During carburization process, rare earth Ce reacts with calcium-enriched phase and forms Ce0.9Ca0.1O1.9 ternary phase. The interaction effect of rare earth Ce with calcium-enriched phase is remarkable. Compared with 1% Ca-YG6 cemented carbide, the density, hardness and fracture toughness of 1% Ce＋1% Ca-YG6 cemented carbide increase by 7.8%, 34.3% and 67.8%, respectively.