The effects of bioceramic coating on corrosion resistance of MA8M and AA6061-T4 alloys

Hydroxyapatite [Ca10(PO4)6(OH)2 (HA), is a calcium phospates based bioceramic material which can be used in biomedical application as bone substitute due to its biocompatibility and near bone properties. It is used as graft or for coating purposes on metallic implants for better osteointegration. Such calcium phospate-based materials promote the implant-bone osteointegration, bone ingrowth and implant-bone fixation. During the coating of implant materials; electrophoretic deposition, plasma spray, PVD (magnetron sputtering) and CVD methods as well as sol-gel method is an effective method. This method, has some advanteges such as low process temperature, possibility of coating complex parts, high surface energy and sinteribility at lower temperatures for the solid substrates.The main goal of this work is to investigate corrosion behaviour of Dip-coated and uncoated Mg and Al alloys. The coating took place by using nano and micro particle sized-HA at different coating thicknesses (~30, ~60 and ~85µm). Corrosion resistance and adhesion strength have been studied with respect to three different coating thicknesses for both micro and nano-HA particle sizes. For this purpose, corrosion tests were carried out in a potansiostat device using Ringer? solution and were characterized by scanning electron microscopy (SEM) and X-ray diffraction. From the analysis, corrosion and adhesion resistance of micro-HA coated Mg specimens was decreased for the coating thickness that is increase. Al alloy were corroded with the activation controlled corrosion mechanism. For the Al alloy samples have been found to be optimum proporties which has been coating ~30µm nano-HA coated Al alloy specimens and for Mg alloy it was found to be ~30µm at micro-HA coating.Keywords: Aluminium and Magnesium, Bioceramic coating, Hydroxyapatite, Corrosion