- South Africa
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AISI 316L austenitic stainless steels are one of the most common biomaterials utilized for producing orthopaedic implants, although they have the limitations of low resistance to wear and fatigue due to low surface hardness. Thus,... more
AISI 316L austenitic stainless steels are one of the most common biomaterials utilized for producing orthopaedic implants, although they have the limitations of low resistance to wear and fatigue due to low surface hardness. Thus, thermochemical surface treatment methods are used to modify the surface properties. In this research, pack carburising with 60% BaCO 3 , 30% activated carbon and 10% NACl was used on AISI 316L austenitic stainless steel at 450ºC, 550ºC, 650ºC, 700ºC and 750ºC for 24 hours. Pack carburised specimens of tensile and fatigue specimens were analysed with optical microscopy, Vicker's micro hardness tester, scanning electron microscopy and XRD. Tensile strengths of specimens treated at 450ºC and 550ºC were 709MPa and 722MPa as compared with the as-received specimen of 645MPa. However, microhardness values of the treated specimens were about the same as the as-received specimens. Hence, the increasing trend in the tensile properties could be attributed to the heat treatment and not the carburising process. Specimens tested at 650ºC, 700ºC and 750ºC showed appreciable increases in tensile strength and microhardness, and specimens carburised at 750ºC experienced deformation. This could be attributed to the onset of recrystallization of the AISI 316L at temperatures above 700ºC.
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The high-temperature solution phase reaction of iron(III) acetylacetonate, Fe(acac)3 and 1,2-hexadecanediol was used to synthesise iron oxide and gold-coated iron oxide nanoparticles. Different surface functionalities, such as sebacic... more
The high-temperature solution phase reaction of iron(III) acetylacetonate, Fe(acac)3 and 1,2-hexadecanediol was used to synthesise iron oxide and gold-coated iron oxide nanoparticles. Different surface functionalities, such as sebacic acid (SA) and 1, 10–Decanediol (DD), were introduced on the surface of the particles to investigate the stabilising effect of carboxylic groups (SA) in comparison to the hydroxyl groups (DD). Nanoparticle thermal
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ABSTRACT Aluminium hybrid composites are a new generation of metal matrix composites that have the potentials of satisfying the recent demands of advanced engineering applications. These demands are met due to improved mechanical... more
ABSTRACT Aluminium hybrid composites are a new generation of metal matrix composites that have the potentials of satisfying the recent demands of advanced engineering applications. These demands are met due to improved mechanical properties, amenability to conventional processing technique and possibility of reducing production cost of aluminium hybrid composites. The performance of these materials is mostly dependent on selecting the right combination of reinforcing materials since some of the processing parameters are associated with the reinforcing particulates. A few combinations of reinforcing particulates have been conceptualized in the design of aluminium hybrid composites. This paper attempts to review the different combination of reinforcing materials used in the processing of hybrid aluminium matrix composites and how it affects the mechanical, corrosion and wear performance of the materials. The major techniques for fabricating these materials are briefly discussed and research areas for further improvement on aluminium hybrid composites are suggested.
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ABSTRACT The nature and magnitude of stress in the scales formed on Pt-11Al-3Cr-2Ru (at.%) alloy oxidized in air at 1250°C, for up to 500 h, were determined. This is to establish their long-term viability during high-temperature... more
ABSTRACT The nature and magnitude of stress in the scales formed on Pt-11Al-3Cr-2Ru (at.%) alloy oxidized in air at 1250°C, for up to 500 h, were determined. This is to establish their long-term viability during high-temperature applications. Residual stress in the scales was measured using luminescence piezospectroscopy and found to be compressive. It decreased gradually with increased oxidation time, before reaching a constant value. The compressive stress was also found to be lower than those of other Ni- and Fe-based superalloys. Thus, the current alloy has a promising potential for high-temperature applications.