In this study, the effects of parameters such as substrate hardness, substrate surface roughness and stand-off distance to the coatings formation and properties of the coatings during cold spraying process were examined. For this purpose, coatings were deposited onto the copper substrate with using of commercially available copper powder. Substrate hardness of 55 HV, 107 HV and 140 HV were obtained by heat treatment and deformation hardening methods. Different substrate surface roughness was obtained by using of SiC emery papers which have different grits and stand-off distance during cold spray process was manipulated as 5, 10, 20 and 30 mm. After the production of the coatings, characterisation procedures were performed by microstructural observations which are optical and scanning electron microscope surveys, porosity concentrations, coating thickness and hardness measurement.
Abstract:The objective of this research is for Ti6Al4V alloy turnings, generated during the machining of implants, to produce powders for the fabrication of Ti base coating via the cold spray method. In order to decrease the cost of powder production and increase the recycling rate of the turnings, the hydrogenation-dehydrogenation (HDH) process has been utilised. The HDH process consists of the following sequence: surface conditioning of the turnings, hydrogenation, ball milling (for powder production), and dehydrogenation. Afterwards, the properties of the recycled powder were analysed via phase, chemical, and morphological examinations, and size and flowability measurements. Usability of the powder in additive manufacturing applications has been evaluated via examining the characteristics of the deposit produced from this powder by the cold spray method. In short, promising results were obtained regarding the potential of the recycled powders in additive manufacturing after making minor adjustments in the HDH process.
This study has been initiated to form a TiO 2 layer having enhanced biological properties on the surface of a CoCr alloy, which is mostly used in manufacturing of orthopaedic implants. As a novel approach, CoCr alloy samples were first coated with titanium and then oxidised in air at 600°C for 60 h. Surface characterisation of the samples were made by structural surveys (scanning electron microscopic examinations, X-ray diffraction analyses), roughness and hardness measurements, bioactivity and wear tests. Results of the experiments have showed that fabrication of TiO 2 as the outermost surface layer caused remarkable increment in the wear resistance and the bioactivity of the CoCr alloy.
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