Browsing by Author "Heness, G"

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    Adhesion of sol-gel derived hydroxyapatite nanocoatings on anodised pure titanium and titanium (Ti6Al4V) alloy substrates
    (Elsevier, 2011-02-25) Roest, R; Latella, BA; Heness, G; Ben-Nissan, B
    The mechanical properties and adhesion behaviour of sol–gel derived hydroxyapatite (HA) nanocoatings on commercially pure (cp) titanium (Ti) and Ti6Al4V alloy have been determined and related to anodising treatment. The surface roughness, wetting and coating characteristics were examined using profilometry, contact angle, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Nano-indentation was used to determine the Young's modulus and hardness of the coatings, while microtensile tests were used to introduce controlled strains in the coatings through the cp Ti and TiAl6V4 alloy substrates, from which the strength, fracture toughness and adhesion behaviour could be ascertained based on multiple cracking and delamination events. The toughness of the HA coatings is found to be slightly lower to that of equivalent bulk pure HA ceramics. The substrate and the anodized layer thickness have the most influence on the interfacial adhesion of HA, with nanocoatings on Ti6Al4V exhibiting superior interfacial bonding in comparison to cp Ti. © 2011, Elsevier Ltd.
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    Small punch test of LC4/SiCP metal matrix composites
    (Trans Tech Publications, 2010-09-17) Mak, J; Wuhrer, R; Humphries, SR; Booth, N; Heness, G; Yeung, WY; Wei, T; Qin, JN; Ouyang, QB; Zhang, D
    There have been growing demands of high performance metal matrix composites in advanced engineering applications in virtue of their high specific strengths. This paper is to report an assessment of the mechanical properties of LC4/SiCp metal matrix composites using an innovative testing technique, small punch test. The composite materials of this study were produced by stir casting method with particulate reinforcements of 7wt.% and 14wt.% of SiC respectively. Small punch testing was performed on the LC4 base alloy and the two composites materials. The small punch test is a relatively new mechanical testing technique capable of utilizing small disk-shaped samples to determine the mechanical properties of the test materials. In this study, the equivalent fracture strain, εqf of the LC4/SiCp MMCs was characterised and compared with the base alloy. The fracture mechanism of the test samples was examined using scanning electron microscopy. © Trans Tech Publications Ltd.
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    A solution for estimating the tensile yield strength from small specimens
    (ASTM Compass, 2013-05-24) Mak, J; Wei, T; Wuhrer, R; Yeung, WY; Heness, G; Zhang, D
    The small punch test is an innovative test that utilises small disc-shaped specimens to assess the mechanical behaviour of materials. The main advantage is the relatively small specimen size. In this article, a modified analytical solution for the small punch maximum bend strength is proposed that is based on classical plate theory. A clear linear relationship is observed between the tensile yield strength σYS and the small punch maximum bend strength σy for both alloys and metal matrix composites. © ASTM International.