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Evaluation Techniques And Improvements Of Adhesion Strength For Tin Coating In Tool Applications: A Review
Faculty of Engineering University of Malaya
The adhesion between coating-substrate systems is an important factor in determining the performance and durability of coated engineering components. This paper reviews the microstructures and adhesion strength of titanium nitride (TiN) coating produced using two different processing methods: chemical vapor deposition and physical vapor deposition. Three methods to evaluate the adhesion strength of the coatings, namely the indentation test, laser spallation technique, and scratch test are presented and discussed in terms of their working principles, their advantages and disadvantages. The extrinsic and intrinsic factors influencing the adhesion strength of coating-substrate system, particularly for TiN coating, are also elaborated. The mechanisms …
Eggshells: A Novel Bio-Filler For Intumescent Flame-Retardant Coatings
Eggshells: A Novel Bio-Filler For Intumescent Flame-Retardant Coatings
Faculty of Engineering University of Malaya
The aim of this study was to develop intumescent flame-retardant coatings that incorporate chicken eggshell (CES) waste as a novel eco-friendly bio-filler. Three flame-retardant additives, namely, ammonium polyphosphate phase II, pentaerythritol and melamine were mixed with flame-retardant fillers and acrylic binder to synthesize the intumescent coatings. The fire performance of the coatings was evaluated in accordance with 'BS 476: Part 6-Fire Propagation' and 'BS 476: Part 7-Surface Spread of Flame' test standards. It was found that 4 out of 5 of the coated specimens (B, C, D and E) neither showed surface spread of flame nor any afterglow combustion upon …
A Novel Combined Severe Plastic Deformation Method For Producing Thin-Walled Ultrafine Grained Cylindrical Tubes
Faculty of Engineering University of Malaya
A novel severe plastic deformation (SPD) process entitled combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE) is proposed for producing thin-walled ultrafine-grained (UFG) tubes. In this new combined SPD approach, the PTCAP and TBE processes are consequently applied to the tube material in which a severe plastic strain is applied to produce a UFG thin-walled tube. This technique was performed on an AZ31 magnesium tube, and a remarkable grain refinement was achieved. The results showed that this method could easily produce a high strength thin walled tube. The microhardness increased significantly to 70 HV after the …
Fabrication And Characterization Of Poly(Octanediol Citrate)/Gallium-Containing Bioglass Microcomposite Scaffolds
Faculty of Engineering University of Malaya
Bone can be affected by osteosarcomae requiring surgical excision of the tumor as part of the treatment regime. Complete removal of cancerous cells is difficult and conventionally requires the removal of a margin of safety around the tumor to offer improved patient prognosis. This work considers a novel series of composite scaffolds based on poly(octanediol citrate) (POC) impregnated with gallium-based bioglass microparticles for possible incorporation into bone following tumor removal. The objective of this research was to fabricate and characterize these scaffolds and subsequently report on their mechanical and biological properties. The porous microcomposite scaffolds with various concentrations of bioglass …
Dissimilar Friction Stir Welding Between Polycarbonate And Aa 7075 Aluminum Alloy
Dissimilar Friction Stir Welding Between Polycarbonate And Aa 7075 Aluminum Alloy
Faculty of Engineering University of Malaya
In this paper, the effects of process parameters, such as the tool rotational and traverse speeds, on temperature evolution and the microstructural and mechanical properties of dissimilar friction stir welding between 3 mm thick AA 7075 aluminum alloy and polycarbonate (PC) plates were investigated. The tool rotational and traverse speeds were varied from 3 000 to 3 500 rpm and 50 to 150 mm min(-1), respectively. The joint fabricated at 3 250 rpm and 100 mm min(-1) yielded a highest tensile load of 586 N. Microstructural analysis of the stir zone revealed an interlock phenomenon, the transportation of AA 7075 …
Study On Coarsening Of Ag3sn Intermetallic Compound In The Fe-Modified Sn-1ag-0.5cu Solder Alloys
Study On Coarsening Of Ag3sn Intermetallic Compound In The Fe-Modified Sn-1ag-0.5cu Solder Alloys
Faculty of Engineering University of Malaya
The present study focuses on coarsening of Ag3Sn intermetallic compound in the Sn-1Ag-0.5Cu and Fe-modified Sn-1Ag-0.5Cu solder alloy. The investigations showed that the Ag3Sn intermetallics coarsened rapidly in the Sn-1Ag-0.5Cu solder alloy whereas the Ag3Sn intermetallics were found to be quite stable in the Fe-modified Sn-1Ag-0.5Cu solder alloy. The lattice strain in the Ag3Sn intermetallics and the blocking effect on Ag diffusivity in Sn matrix suggested the possible mechanisms for the coarsening suppression of the Ag3Sn intermetallics in the Fe-modified solder alloy. (C) 2014 Elsevier B.V. All rights reserved. Link to Full-Text Articles : http://www.sciencedirect.com/science/article/pii/S0925838814024621
Alternative Methods To Determine The Elastoplastic Properties Of Sintered Hydroxyapatite From Nanoindentation Testing
Faculty of Engineering University of Malaya
This study introduces alternative methods to determine the elastoplastic properties of bovine-derived Hydroxyapatite (HA) porous bone graft through a set of nanoindentation tests with a Berkovich indenter. Generally, experimental data obtained from nanoindentation tests are force displacement, hardness and elastic modulus. However, to determine plastic properties such as strength coefficient and work hardening exponent of bovine HA, analytical or inverse finite element models are required. In this paper, the effect of sintering temperature on these properties of HA is studied for the range of 1000-1400 degrees C. The direct and inverse Finite Element (FE) simulation models for nanoindentation tests were …
Properties Of Zn-Bi Composite Coatings Prepared By Ionic Co-Discharge Deposition
Properties Of Zn-Bi Composite Coatings Prepared By Ionic Co-Discharge Deposition
Faculty of Engineering University of Malaya
Zn-Bi composite was synthesized by ionic co-discharge deposition and its properties were investigated. The results show that the Zn-Bi composite with the incorporation of Bi has a finer grain size than the pure Zn coating and improves the mechanical properties. The microhardness is increased by approximately two times simply by adding a small amount of Bi electrolyte into a Zn bath solution. A lower volume loss of the Zn-Bi composite coating compared with the pure Zn coating also indicates that the Zn-Bi coating has a better wear resistance. Link to Full-Text Articles : http://www.sciencedirect.com/science/article/pii/S1003632615635968