Application of Ni-B based coating on AZ91Dmagnesium alloy and examination of itscharacteristics

Magnesium alloys are one of the most preferred alloys in recent years due to their light and strength. However, corrosion and oxidation resistance are very low alloys. Therefore, in recent years, many studies have been carried out to increase the surface performance of the magnesium alloys. In this study, it is planned to investigate the electrochemical coating and properties of double layer Ni-P/Ni-B coatings on AZ91D Magnesium alloy. Magnesium alloys with a low corrosion resistance material. Because of their galvanic effect during the electroless coating, it affects the corrosion properties badly and makes the coating process difficult. For this reason, T6 heat treatment is applied firstly before the coatings on AZ91D magnesium alloys. The heat treatment process is carried out in two stages as the solute solution and aging process. Dublex Ni-P/Ni-B coating was produced in two stages as cast and T6 heat-treated AZ91D Magnesium alloy. Since the effects of both coating types on the AZ91D Magnesium alloy are different, the coating process is produced using two separate bathrooms. The time and temperature parameters of the prepared baths were changed and their effects on the properties of the coatings were investigated. After plating, coating surfaces were examined by scanning electron microscope (SEM) and the chemical composition of the coating layer was determined by Energy Dispersive Spectrometry (EDS) analysis. A comparison of duplex Ni-P/Ni-B coatings, which were performed on two types of substrates, were investigated for hardness, wear, corrosion resistance and surface roughness measurements. As a result of the corrosion test, the coatings which have superior protection compared to the AZ91D alloy have been compared within themselves. Other characterization studies showed that the coating parameters that exhibit the best wear resistance, the lowest surface roughness value, the highest hardness and the most homogeneous structure in the coatings were determined.