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3. Fabrication of miniature components using nano

Author

Zakaria, Hafizawati

Abstract

The miniaturization of components is gaining importance in many microsystem technologies such as medical technology, biotechnology and drive technology. In this study, two types nano-sized powder, metal (stainless steel 316L) and ceramic (ytria stabilized zirconia, YSZ) has been used to fabricate miniature parts by micro powder injection moulding process. Micro parts have been produced by mixing of powders with a binder system, injection, debinding and sintering process respectively. Due to the agglomeration of fine powder and environmentally hazard of organic binder, the partially water soluble binder system with surfactant addition has been used to mix with 316L or YSZ nano-powder to form feedstock. The PEG loss in water is observed by a rapidly removal period for the first 60 min immersion for micro parts. The PMMA binder is removed to 97% after the pyrolysis process at 450 ⁰C and 2.5h. Sintered ceramic and metallic parts showed that relative density about 97% of theoretical density and free defect. Hardness around 212 Hv and 1200 Hv has been achieved for fabricated micro parts using SS 316L and YSZ powders respectively.

Published
2017
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9. Characterization of Fabricated Feedstock Using Nano Powders and a Water-Soluble Binder in Micro Metal Injection Molding

Author

Javad, Rajabi, Muhamad, Norhamidi, Sulong, Abu Bakar, Hasyimah, Aziz, Fayyaz, Abdolali, and Zakaria, Hafizawati

Abstract

Micro metal injection molding has become the promising method in powder metallurgy research in order to fabricate small-scale intricate parts in an influential process and competitive cost of mass production. Stainless steel 316 L powders with powder size of 150 nm and 5 μm were mixed with a binder with a water soluble component which consisted of a major fraction of water soluble Polyethylene Glycol (PEG), a minor fraction of polymethyl-methacrylate (PMMA) and some stearic acid has been used as a surfactant. This work aims to investigate the rheological properties of a feedstock which are efficiently characterised by capillary Rheometry to measure apparent viscosities at different temperatures and shear rates. Results obtained by the varying feedstock characteristics, when viscosity decreases by increasing of shear rate at certain temperature feedstock should have a pseudoplastic behaviour. Melt viscosity of the feedstock was decreased by adding nanoscale powders. The reduced (n) values at high temperature with addition of nanoparticles indicated a possible increase in the shear-thinning behavior.

Published
2008
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