纯钨零件的粉末注射成形工艺研究

本文以高能球磨钨粉和高纯钨粉为原料，采用粉末注射成形技术成功制备出具有复杂形状的纯钨及添加稀土的钨零件。重点研究了注射成形工艺参数对其微观结构及其力学性能的影响规律。研究结果表明，以高能球磨后的钨粉和Y2O3为原料，采用注射成形工艺可制备出烧结密度为18．26g／cm^3，相对密度为94．61％的钨零件，较佳的工艺参数为：粉末装载量为52％，注射温度为165℃，注射压力为65MPa，烧结温度为2300℃。研究结果还表明：稀土元素氧化物的添加，可显著提高注射成形钨零件的烧结密度，明显细化烧结后样品的晶粒。这是由于稀土氧化物作为第二相粒子弥散分布于晶界处，阻碍了位错的运动和高温烧结时晶粒的长大。

Injection Molding of Tungsten Powders

In this paper, W and Y2O3-addited W parts with complex shape were prepared by powder injection molding, and the effects of parameter of injection molding on the microstructure and mechanical properties were investigated. The results showed that tungsten part with relative density of 94.61 % was obtained from powders of ball-milled tungsten powder and Y2O3 by powder injection molding. When the powder loading was 65%, the optimum parameters for injection molding are 165℃ for injection temperature and 65MPa for injection pressure. It was found that the addition of Y2O3 could improve the density and decrease the grain size of the sintered parts remarkably, which was mainly attributed to the distribution of second phase mainly from Y2O3 at the interface between the grains in sintered parts. Because of the distribution of second phase, the movement of the dislocations and the growth of the grains in parts were restrained significantly.