Mohd Asri Selamat

Comparison Study in Consolidation of Yttria Reinforced Iron-Chromium Composites Using Conventional and Microwave Sintering Technique

This research is focused on studying the density and mechanical properties of iron-chromium composites consolidated by innovative rapid microwave sintering technology against conventionally sintered counterparts using slow heating crucible furnace. Another aim of this study is to assess the viability of yttria (Y2O3) ceramic particulates as reinforcement to the iron-chromium composites. Fabrication of iron-chromium-yttria composites consolidated in microwave furnace and conventional crucible furnace was successfully accomplished. Improvement of density is evident in microwave sintered composites. The Y2O3 addition significantly increases the hardness of the composite (118 Hv for microwave specimens as opposed to 110Hv for conventional specimens). The study also successfully established the viability of microwave sintering technique for consolidating iron based powder metallurgy composites by up to 80% reduction of sintering time.

Physical and Mechanical Properties of WC-Co Submicron Powders Using P/M Technique

The properties of WC-Co are greatly improved with the use of submicron powders. However, grain growth tends to occur during the sintering process which causes the properties to deteriorate to some extent. Free carbon and vanadium carbide are added in this study to serve as grain growth inhibitor. The effect of these two materials is evaluated based on WC-Co properties. In this work, the powders are mixed together via wet mixing process, compacted and undergo cold-isostatic pressing (CIP) before the samples are sintered in the temperature range of 1350-1450°C under nitrogen-based atmosphere. The physical and mechanical properties of the WC-Co sintered powders were analysed. Based on the work done, the WC-Co-C has a better properties compared to WC-Co-VC.

Optimisation of End Milling Machining Parameters Using the Taguchi Method and ANOVA of AlSi/AlN Metal Matrix Composite Material

Abstract. The purpose of this research is to determine the optimum machining parameter for Aluminium silicon alloy (AlSi) matrix composite, which has been reinforced with aluminium nitride (AlN), with three types of carbide inserts present. Experiments were conducted at various cutting speeds, feed rates and depths of cut, according to the Taguchi orthogonal array L27. The signal-to-noise (S/N) ratio and analysis of variance are applied to study the characteristic performance of cutting speeds, feed rates, depths of cut and types of tool in measuring the tool life during the milling operation. The analysis of wear was done using a Sometech SV-35 video microscope according to ISO 3686. Through Taguchi analysis, it is concluded that a combination of high feed rate, high depth of cut, low cutting speed and insert TiB2 give a longer tool life. Therefore, the cutting speed of 230 m/min, feed rate of 0.8 mm/tooth, depth of cut of 0.5 mm and type of insert of TiB2 were the optimum machining parameters. These optimum parameters will help the automotive industry to have a competitive machining operation from both economical and manufacturing perspectives.

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...

Friction and Wear Characteristics of Cu-Based P/M Brake Friction Materials with Addition of Fe and C

Cu-based powder metallurgy friction materials were prepared by varying of Fe and C (% weight) in the friction components. The samples were compacted under the load of 24 metric tonnes and sintered at a temperature of 950 °C for 45 minutes. The friction and wear characteristics the materials developed were studied using Chase machine. The results show that Fe and C have different friction and wear characteristics. The friction coefficient of Cu-30%Fe-15%C sample maintained to be high and slightly increased after the drum temperature of 350°C and subsequently stable throughout tests. The friction of Cu-20%Fe-10%C stable until the drum temperature of 450°C and then its start to decay slightly until the end of the test. On the hand, the friction of Cu-10%Fe-5%C start to decay after sliding a few minutes at the drum temperature of 230°C. Thus, it could be postulated that the friction coefficient increased with increasing weight percentage of Fe and C in the friction components. However, the volume loss shows that there is no direct correlation with the Fe and C content. The volume loss of Cu-10%Fe-5%C was higher than the two samples which had the lowest hardness. On the hand, the volume loss of the Cu-30%Fe-15%C was slightly higher than Cu20%Fe-10%C as result of higher porosity and lower hardness. Wear mechanisms of abrasion, adhesion and thermal were observed to be operated during sliding process.

Physical, mechanical and electrical properties of W-20 wt.% Cu composite produced by liquid phase sintering process

In this study, the effect of sintering temperature on the properties of tungsten-copper (W-Cu) composite produced by liquid phase sintering (LPS) process has been investigated. W-20 wt.% Cu composite powders with particle size less than 1 μm was prepared by cold compaction and followed by cold isostatic pressing. The green specimens were then sintered under nitrogen based atmosphere in the temperature range of 1100°C to 1300°C. The sintering studies were conducted to determine the extent of densification and corresponding to microstructure changes. In addition, the properties of the sintered specimens such as physical appearance, microstructure evolution, mechanical and electrical properties were presented and discussed.

Effect of Heat Treatment Process of Sintered M3/2 High Speed Steel Parts

Dry machining is one of the ways to achieve a reduction of cooling lubricants, as well as reduced environmental pollution and lower health risk to workers. This leads to higher mechanical and thermal loading on cutting edges. The adaptation of cutting tools to the requirements of dry machining includes the optimisation of manufacturing technologies, the development of cutting materials of sufficient toughness and high hot hardness, the design of tool geometries as well as the coating of tools [.

Effect of Compaction Load and Heat Treatment in Manufacturing of HSS Cutting Inserts under Nitrogen-Based Atmosphere

High speed steels (HSS) is used in manufacturing of cutting tools and wear components because of its superior mechanical properties and wear resistance. In this study, the optimization manufacturing parameters such as compacting pressure and heat treatment temperatures will be studied. The powder of HSS and iron phosphorous were dryly mixed for 30 minutes. The mixed powders were compacted at the pressure in the range of 300- 632 MPa, sintered in the temperature range of 1100 - 1225 °C, annealed in the temperature range of 1100 - 1175 °C and tempered in the temperature range of 500 - 600 °C. The mechanical properties of the samples are analyzed using Vicker’s microhardness tester, universal tensile machine and the microstructures of the sintered sample were observed using field emission scanning electron microscope. Test results revealed that the optimum manufacturing parameters are as follows; (i) compacting pressure of 632 MPa, (ii) sintering temperature of 1200°C, (iii) annealing temperature of 1175 °C, (iv) tempering temperature of 500 °C.

Characteristics of Fe-Yttria Composites Fabricated by Powder Metallurgy Method

This study is focused on fabricating and characterizing iron (Fe) composites prepared by powder metallurgy route reinforced with varying weight of Yttria (Y2O3). Composites were prepared based on 5 wt. % to 15 wt. % of reinforcement powder with particle size ranging from 1-10µm. Pure Fe matrix composites were also prepared for comparison purpose. This paper will report the microstructure, bulk density and micro hardness values of the composites. Powder characterization and microstructures of the composites were examined using Scanning Electron Microscope (SEM) which indicated homogenous distribution of reinforcement particles in the metal matrix. Bulk density of the composites was calculated using standard Archimedean method showing decreasing values as the weight percentage of Y2O3 increases. Micro-hardness was measured using micro-Vickers hardness instrument. The data obtained shows that the Fe-Y2O3 composites samples possessed superior hardness value with the increasing quantity of reinforcement compared to the unreinforced Fe composite.