The Effect of Substrate Temperature on Structural, Adhesion and Corrosion Behavior of HA / ZrN Coated AZ91 Magnesium Alloy Created by Ion Beam Sputtering

In this study, the ion beam sputtering method was used to deposit the optimized ZrN coating with 1 μm thickness on AZ91 magnesium alloy at 400 °C and then the HA coatings were created on them at temperatures of 150 °C, 200, 250, 300, and 350 °C for 360 minutes. The profilometry and indentation methods for thickness and film adhesion evaluation showed that, from 150 to 300 °C the thickness decreases from 8.1 μm to 3.3 μm and dp/dr ratio increases from 0.07 to 0.2 kg/μm. The analysis of the x-ray diffraction pattern by Williamson - Hall method showed that, by increasing the temperature to 300 °C the grain growth is dominated therefore the grain size reaches to 0.36 μm, but with increasing the temperature to 350 °C, grain size decreases to 0.12 μm. The potentiodynamic polarization test showed that, all coated samples have corrosion potential close to AZ91 about 1.54 Volt vs. SCE and the corrosion current density in the deposited samples at 300°C showed the minimum current density about 0. 33 μA/cm2.