Salina Budin

Physical and mechanical properties of injection moulded 316L stainless steel using waste rubber binder

Metal Injection Moulding (MIM) is a cost-effective method in producing a variety of small and high performance parts. This paper investigates the influence of waste rubber binder combined with polyethylene binder on the properties of injection moulded 316L stainless steel. Feedstock formulation was prepared using 32 µm 316L SS powder and mixed with binder system containing 55 wt.% paraffin wax, 35 wt.% PE/WR and 10 wt.% stearic acid. The feedstock was then successfully injection moulded at powder loading of 0.65. The specimens were immersed in n-heptane for five hours at 60 °C in order to remove the paraffin wax and stearic acid. Debinding process produced the defect-free green parts. The parts were then sintered in vacuum atmosphere at temperature ranges of 1320 °C to 1360 °C. The results showed that the highest density achieved was 7.612 g/cm3 at temperature of 1360 °C with tensile strength of 497 MPa while the highest hardness was achieved at 274.8 HV.

Optimization of Warm Compaction Process Parameters in Synthesizing Carbon-Copper Composite Using Taguchi Method

Carbon–copper composites are attractive materials used for electrical applications, such as brushes for engines and generators, slip rings, switches, relays, lugs, contactor and current collector. Various methods can be used to prepare Carbon-copper composite, such as infiltration, sintering, cold pressing, hot pressing or isostatic pressing. However, powder metallurgy route is seen to be most favorable due to its possibility of producing uniform microstructure and excellent net shape product. In this work, carbon-copper composite is prepared using powder metallurgy route with warm compaction process. The compaction pressure (A), compaction temperature (B), post baking temperature (C) and compaction time (D) were optimized by Taguchi method. Hardness and transverse rupture strength (TRS) were used to assess the effect of warm compaction process. The experimental design is according to the L9 (34) orthogonal array. Signal to noise and analysis of variance (ANOVA) are employed to analyze the effect of warm compaction parameters. It is found that the best parameters and their levels are A3B2C3D2 for the main effect of hardness and the best parameters and their levels for TRS is A3B2C3D1. It is also notified that optimized parameters of A3, B2 and C3 are identical for hardness and TRS. However, for parameter D, the best level for hardness is D2 and for TRS is D1. The ANOVA analysis proved that compaction temperature parameter is significant to hardness and TRS value whereas the others parameters are not significant.

Microstructure and mechanical properties of high speed steel with addition of ferrophosphorus on sintering temperature

High speed steel (HSS) is one of the important engineering materials especially for cutting material due to its superior properties. In this work, M2 HSS with addition of ferrophosphorus (Fe3P) are processed using conventional powder metallurgy route; mixing, compaction and sintering. The main objective of this work is to investigate the microstructure and mechanical properties ie, hardness and transverse rupture strength (TRS) in addition of Fe3P on sintering temperature. The mixtures are compacted at 15 tonnes and sintered at sintering temperature of 1100°C, 1140°C, 1180°C and 1220°C. The microstructural analysis using scanning electron microscope (SEM) shows the level of porosity decreases as sintering temperature increases which has indicated that denser sintered samples are obtained at high sintering temperature. The hardness result is in the similar trend where the hardness increases as sintering temperature increases. The maximum hardness of 458 HV is obtained at sintering temperature of 1220°C. Al...