Net shape fabrication of stainless steel–alumina composite micro parts

Abstract

This paper presents a successful method to fabricate high-quality composite micro parts. The fabrication process starts with producing SU-8 aster moulds using photolithography technique, mirror replication of PDMS soft moulds, preparing composite slurry using super fine 316-L stainless steel (5 µm) and α-alumina powder (⩽400 nm) in 2.5, 5, 7.5 and 10 wt%, filling the moulds, obtaining the green parts, de-binding and sintering. A new method was used in this research to homogenize the alumina particles in a stainless steel composite slurry. Stainless steel and alumina powders were dispersed separately in distilled water and dispersant. Then, the two dispersed powders were mixed together to form a homogeneous composite slurry. The process resulted in high-quality composite micro parts which retain the very details of the SU-8 master moulds. The internal structures of the green and sintered micro parts showed homogeneous distribution of alumina particles in a stainless steel matrix. The density and micro hardness of the sintered parts were also investigated in detail for different stainless steel alumina compositions.