Influence of the Morphology and Particle Size on the Processing of Bronze 90/10 Powders by Metal Injection Moulding (MIM)

Abstract

The MIM technology is an alternative process for fabricating near net shape components that usually uses gas atomised powders with small size (< 20 μm) and spherical shape. In this work, the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that is cheaper than the former was investigated. Different bronze 90/10 components were fabricated by mixing three different types of powder: gas atomised spherical powder (usual MIM powder < 22 μm) and two water atomised irregular powders (size < 35 μm and < 140 μm). The blends were made by using only two types of powder in each mixture with the following volume proportions (100/0, 67/33, 33/67, 0/100). The influence of the particle size and shape on the powder packing density and sintering stage was analyzed through the apparent density of the powder blends, as well as, densification, hardness and porosity of the sintered parts. The addition of irregular and/or coarse powder was found to affect the moulding process, although good densifications and hardnesses were obtained in the sintering step. Therefore it could be a promising way to diminish production costs in this technology.