Papers by Author: Siew Fei Pook

Abstract: Powder injection molding technology is currently applied to the joining processes to produce multi-functional components. In this paper, the strength of the joint of green and sintered samples produced by powder injection molding was evaluated using four-point bending test. The microstructures of the green samples showed that a very good joint was formed by the re-melting of the first injection molded half part followed by a high pressure compacting in the second injection molding. The strength of joined green samples was almost equal to the reference green samples without joining. The microstructures and flexure strength of sintered joined samples, which was more than 90% of base materials, showed that the good joining was maintained after sintering. This high strength sintered joint was an integrative result of powder injection molding and sintering diffusion. The crack observed at the sample surface accounted for the slight drop of the strength.

Abstract: Titanium alloy is an attractive material for aerospace and automobile applications due to its lightweight and high strength. Titanium metal matrix composite (MMCs) is one of the promising materials which could be employed to enhance stiffness and wear resistance of titanium alloy. In this study, reinforcement of in-situ and ex-situ particulates has been investigated. The experimental results show that a dense microstructure with uniformly distributed in-situ TiB reinforcement phase in the Ti+B+Sn system could be obtained. It is present in either needle or blocky shape. This process involved warm pressing of mixed powder in semi-solid stage followed by sintering, which eliminated costly CIP and HIP processes. However, it is found that the ex-situ particulates in the titanium metal matrix are not suitable as reinforcements in Ti-Sn metal matrix as they either reacted with titanium during sintering process or generated a void at the interface between the reinforcement and the matrix.