Dimension precision of metal injection molded pure tungsten

The pure tungsten compacts with complex shape were fabricated by metal injection molding (MIM). The properties of the compacts were evaluated by scanning electron microscopy, thermal analysis and mechanical property testing. The effects of processing parameters on the properties of final part were investigated in detail and the optimal process of MIM was obtained. After sintering at 2300 °C for 180 min in hydrogen atmosphere, the relative density of pure tungsten part can reach 92.86%. It was determined, by statistical measure of variance that the dimension precision of these parts can be controlled in ±0.09%. The experimental results showed that the dimension precision of molding stage has an important effect on the dimension precision of the final parts. The injection pressure and the sintering temperature are the most important processing parameters for the dimension precision and properties of the final material. Due to the effect of gravity, the shrinkage ratio on the vertical direction is about 0.5% more than that on the horizontal direction.