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Almaslow A.,National University of Malaysia | Ghazali M.J.,National University of Malaysia | Talib R.J.,Advanced Materials Research Center | Ratnam C.T.,Malaysian Nuclear Agency | Azhari C.H.,National University of Malaysia

A group of semi-metallic friction composites (SMFC) consisting of epoxidized natural rubber-alumina nanoparticles (ENRAN), steel wool, graphite, and benzoxazine were prepared using a melt mixing method. The mixing work was carried out at 90°C. The composites were vulcanized by electron beam irradiation. The samples were then subjected to mechanical and physical tests to determine the tribological properties of SMFC. Detailed examinations on the worked layer were analyzed using a scanning electron microscopy with an energy dispersive X-ray. Samples with 29% of ENRAN exhibited the best friction coefficient (~0.437) with low specific wear rates (0.27×10-7cm3/Nm). An iron oxide formation was prominent on the friction surfaces, implying the occurrence of interactions between the contacting surfaces and the environment. © 2013 Elsevier B.V. Source

Mahammad Rafter M.F.,University Tun Hussein Onn Malaysia | Ahmad S.,University Tun Hussein Onn Malaysia | Ibrahim R.,Advanced Materials Research Center
Materials Science Forum

Nowadays, the 316L stainless steel metal foams (SS316L) have acknowledged important attention in various fields and are required to be used as engineering materials including heat exchange, sound absorption, filtration and others. So, in this study the production of SS316L foams using different composition through compaction method by using a starch powder as space holder was studied. The range of selected composition of SS316L that obtained is between 50 wt.% to 60 wt.% while the remaining percentages are space holder and binder. The SS316L compact is prepared by mixing SS316L alloy powder, starch powder, and Polyethylene Glycol (PEG). Then, the mixture is compact into a mould under 8 tonnes of controlled pressure using hydraulic press machine. This is later sintered in a vacuum furnace. The sintered SS316L foams were characterized using a Scanning Electron Microscopy (SEM) analysis. Then, the physical properties of SS316L foam was also analysed by Archimedes method that includes porosity and bulk density test. As a result, the sample with 60 wt.% were produced a good and finer pores and struts. Meanwhile, for that sample the percentage of porosity and bulk density are 0.19% and 7.44 g/cm3, respectively. © 2016 Trans Tech Publications, Switzerland. Source

Jamuna-Thevi K.,Advanced Materials Research Center | Jamuna-Thevi K.,University of Technology Malaysia | Daud N.M.,University of Technology Malaysia | Abdul Kadir M.R.,University of Technology Malaysia | Hermawan H.,University of Technology Malaysia
Ceramics International

The synthesis of multiple ions doped nanoapatite powder was carried out by wet precipitation technique. A newly developed reaction route with self-controlled pH at high reaction temperatures, i.e. 37 & 85±2 C was compared to the conventional synthesis route at 37±2 C. The XRD peaks were very broad, indicating the presence of nanocrystalline apatite. The primary particle size of the powder was in the range of 20-30 nm whereas the fraction of crystallinity was between 0.20 and 0.63. TEM and SEM characterizations confirmed the nanosized primary particles of the apatite samples. The high temperature synthesis at 37 & 85±2 C improved both crystallite size and crystallinity of the as-prepared samples. A highly crystalline HA phase was formed in the ions doped samples without secondary phases, indicating its thermal stability at 900 C in both CO2 and air atmosphere. The in vitro cytocompatibility of the synthesised nanoapatite powders was confirmed by cell viability of human skin fibroblasts. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source

Raza M.R.,Petronas University of Technology | Ahmad F.,Petronas University of Technology | Omar M.A.,Advanced Materials Research Center | German R.M.,San Diego State University
Journal of Materials Processing Technology

This study presents the results of corrosion behavior of powder injection molded 316L stainless steel parts sintered in vacuum. The feedstocks of metal powder and plastic binder were prepared and their viscosity was measured. Green samples were injection molded and binder was removed from the green parts. Brown test parts were sintered at 1325 °C with heating rate of 5 °C/min and 10 °C/min for 2 h followed by the same cooling rate. Corrosion response of the sintered test samples was measured by weight loss method in Ringer's Solution of pH 7.4 for 15 days. The test samples using cooling rate 10 °C/min showed higher mechanical properties and improved corrosion resistance compared to those sintered at low heating and cooling rate. High cooling rate reduced the evaporation of Cr and developed passive chromium oxide layer on the test samples resulting improved corrosion resistance. © 2011 Elsevier B.V. All rights reserved. Source

Lim C.K.,University of Malaya | Halim A.S.,University of Malaya | Yaacob N.S.,Universiti Sains Malaysia | Zainol I.,Sultan Idris University of Education | Noorsal K.,Advanced Materials Research Center
Journal of Bioscience and Bioengineering

The effects of locally produced chitosan (CPSRT-NC-bicarbonate) in the intervention of keloid pathogenesis were investigated in vitro. A human keratinocyte-fibroblast co-culture model was established to investigate the protein levels of human collagen type-I, III and V in a western blotting analysis, the secreted transforming growth factor-β1 (TGF-β1) in an enzyme-linked immunosorbent assay (ELISA) and the mRNA levels of TGF-β1's intracellular signaling molecules (SMAD2, 3, 4 and 7) in a real-time PCR analysis. Keratinocyte-fibroblast co-cultures were maintained in DKSFM:DMEM:F12 (2:2:1) medium. Collagen type-I was found to be the dominant form in primary normal human dermal fibroblast (pNHDF) co-cultures, whereas collagen type-III was more abundant in primary keloid-derived human dermal fibroblast (pKHDF) co-cultures. Collagen type-V was present as a minor component in the skin. TGF-β1, SMAD2 and SMAD4 were expressed more in the pKHDF than the pNHDF co-cultures. Co-cultures with normal keratinocytes suppressed collagen type-III, SMAD2, SMAD4 and TGF-β1 expressions and CPSRT-NC-bicarbonate enhanced this effect. In conclusion, the CPSRT-NC-bicarbonate in association with normal-derived keratinocytes demonstrated an ability to reduce TGF-β1, SMAD2 and SMAD4 expressions in keloid-derived fibroblast cultures, which may be useful in keloid intervention. © 2012 The Society for Biotechnology, Japan. Source

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