Influence of heat treatment on crystal structure and corrosion properties of Co-Cr-Mo-Al alloy in simulated body fluid solution.

Abstract

One of the biocompatibility properties of cobalt alloys as a biomaterial is the corrosion resistance of the alloy to the biological environments such as Simulated Body Fluid (SBF). Cobalt alloys have two dominant crystal structures the FCC and HCP structures. The Co-Cr-Mo-Al alloy were subjected to the heat treatment at a temperature of 1000 °C, with various holding time, 4, 6, and 8 hours. Observation of the crystal structure of the alloy was conducted by using x-ray diffraction and the corrosion resistance was carried out by the voltammetry method, Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) in Simulated Body Fluid (SBF) at a temperature of 37 °C. From x-ray diffraction pattern, it is known that heat treatment increases the crystallite size of the alloy and alter the lattice parameters. The variations in the holding time of heating lead increase the concentration of the Face Centre Cube (FCC) crystal structures in the alloy. Observation of Cyclic Voltammetry show that the reaction of the formation of passive layers takes place spontaneously in an SBF environment. LSV data were used to determine the changes density current of corrosion of alloy. A low corrosion rate is found in alloy that untreated heat. It can conclude that heat treatment with different holding time affect on the crystal structure and corrosion properties of Co-Cr-Mo-Al alloys in the SBF solution.