http://hdl.handle.net/10204/922 2013-06-19T15:50:33Z http://hdl.handle.net/10204/6787 Title: Corrosion of WC-VC-Co hardmetal in neutral chloride containing media Authors: Machio, CN; Konadu, DS; Potgieter, JH; Potgieter-Vermaak, S; Van der Merwe, J Abstract: Corrosion is an important surface degradation process in some, if not all, applications of tungsten-carbide-(WC-) cobalt- (Co-) based hardmetals. Applications like tools for machining of metals and for wear resistance in the mining industry expose the WC-Co to fluids that can be corrosive, leading to a reduced useful life. The Co binder is the least corrosion resistant constituent, and efforts to improve WC-Co corrosion resistance have involved altering the chemical composition of the binder by introducing more corrosion resistant elements. Nickel, and chromium especially, and recently, ruthenium have been shown to markedly improve the corrosion resistance of WC-Co-based hardmetal Description: Copyright: 2013 Hindawi Publishing Corporation. This is the definitive version of the work. 2013-01-01T00:00:00Z http://hdl.handle.net/10204/6708 Title: Effects of Ti and TiC ceramic powder on laser-cladded Ti-6Al-4V in situ intermetallic composite Authors: Ochonogora, OF; Meacock, C; Abdulwahaba, M; Pityana, S; Popoolaa, API Abstract: Titanium metal matrix composite (MMCs) was developed on titanium alloy (Ti–6Al–4V) substrate with the aim of improving the hardness and wear properties by laser cladding technique using a Rofin Sinar 4 kW Nd: YAG laser. Wear investigations were carried out with the aid of three body abrasion tester. The resultant microstructure show homogeneous distribution of TiC particles free from cracks and pores. Multiple track deposited systems with 50% overlap revealed micro-hardness increase from 357.3 HV0.1for the substrate reaching a peak as high as 922.2 HV0.1 for 60%Ti + 40%TiC and the least 665.3 HV0.1 for 80%Ti + 20%TiC MMCs. The wear resistance of the materials improved significantly, indicating a fifteen-fold wear rate reduction due to the proper distribution of ceramic particles thereby forming interstitial carbides as revealed by the X-ray diffraction spectrum. Description: Copyright: 2012 Elsevier. This is an ABSTRACT ONLY. The definitive version is published in Applied Surface Science, vol. 263, pp 591-596 2012-12-01T00:00:00Z http://hdl.handle.net/10204/6702 Title: Impact toughness of laser surface alloyed Aluminium Authors: Mabhali, LAB; Sacks, N; Pityana, S Abstract: Laser surface alloying of aluminium AA1200 was performed with a 4kW Nd:YAG laser and the impact resistance of the alloys was investigated. The alloying powders were a mixture of Ni, Ti and SiC in different proportions. Surfaces reinforced with intermetallic phases and metal matrix composites were achieved during laser alloying. Brittle fracture of the SiC particles and transgranular cracking of the intermetallic phases was observed for the laser alloyed samples, while ductile fracture was observed for the bulk aluminium. The aluminium metal absorbed more energy during fracture compared to the laser alloyed samples due to its high ductility. Laser alloyed layers with a high Ti content had high absorbed energies which represent a reduction in brittleness, while alloyed layers with a high Ni content had low absorbed energies which indicate a preference for brittle fracture. Description: Copyright: 2012 Elsevier. This is the Pre/post print version of the work. The definitive version is published in Journal of Materials Science & Technology, pp 1-29 2012-03-01T00:00:00Z http://hdl.handle.net/10204/6680 Title: Effect of laser power and scanning speed on laser deposited Ti6Al4V/TiB2 matrix composites Authors: Mokgalaka, MN; Pityana, SL; Popoola, API; Meacock, C Abstract: Titanium is an attractive choice for many components in the aerospace, automotive and biomedical industry. It is frequently chosen as one of the preferred alloys for parts and components due to the excellent combination of specific mechanical properties they exhibit. Description: Additive Manufacturing in Industry Conference, Kwa Maritane, Pilanesberg National Park, 31 October-2 November 2012 2012-10-01T00:00:00Z