Fabrication of miniature parts using nano-sized powders and an environmentally friendly binder through micro powder injection molding

Abstract

Component miniaturization is increasingly gaining importance in numerous microsystem technologies, including medical technology, biotechnology, and drive technology. In this study, two types of nano-sized powder, namely, metal (stainless steel 316L) and ceramic (yttria-stabilized zirconia), were used to fabricate miniature parts through micro powder injection molding. Micro parts were produced by mixing powders with a binder system, followed by injection, debinding, and sintering process. Partially water-soluble binder system with surfactant addition was used to mix with either stainless steel 316L or yttria-stabilized zirconia nanopowder to form feedstock to avoid the agglomeration of fine powder and environmentally hazardous organic binder. The polyethylene glycol loss in water was observed after a rapid removal period in the first 60 min of immersion for the micro parts. Approximately 99 % of the polymethyl methacrylate binder was removed after pyrolysis at 450 °C for 2.5 h. Sintered ceramic and metallic parts showed a relative density that is approximately 97 % of theoretical density and free of defects. Hardness of approximately 221 and 1,200 Hv was achieved for the fabricated micro parts using stainless steel 316L and yttria-stabilized zirconia powders, respectively.