THE EFFECTS OF SHOT PEENING AND ANODIZATION VOLTAGE VARIATION ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AZ91D MAGNESIUM ALLOY FOR BIODEGRADABLE ORTHOPEDIC IMPLANT APPLICATIONS

• Main Author: Puspa Paramesti, Prima
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57730
• Institution: Institut Teknologi Bandung

Magnesium is one of the metal materials that can be used as biodegradable implants. Magnesium has better biocompatibility and most bone-like mechanical properties compared to other implant materials. However, magnesium and its alloys also have disadvantages, namely high corrosion rates and rapid degradation. Various studies have been carried out such as surface treatment and coating to improve the corrosion resistance of magnesium alloys. Nonetheless, these techniques still result in a loss of other aspects that can degrade biocompatibility. In this research, the combination of shot peening and anodization methods will be used to improve the corrosion resistance and mechanical properties of magnesium alloy. The alloy used in this study is magnesium alloy AZ91D. The study began with cutting and specimen preparation. Shot peening with a small steel ball projectile was applied to the cut specimens for 12 minutes. After that the specimens were anodized at various voltages of 3 V, 5 V, and 8 V. For each voltage, the anodization process was carried out for 60 minutes in a solution comprising 3 M KOH + 1 M Na2SiO3. The specimens were characterized using Optical Microscope, Scanning Electron Microscope, and X-Ray Diffraction. Several tests of mechanical properties were also conducted, namely the vickers hardness test and the surface roughness test. After obtaining characterization and testing data, the AZ91D alloy was subjected to an investigation of the microstructure, morphology, and phase formed on the surface as well as the hardness and roughness upon being shot-peened and anodized. From the experimental results, it can be detected that a layer consisting of Mg(OH)2 and Mg2SiO4 formed on the surface of the AZ91D alloy after anodizing. Specimens with a voltage of 5 V have the thickest and most porous coating. The anodizing treatment also enhance the hardness and roughness of the specimen. The highest hardness value is 48,93 HV with an increase in hardness of 23,87% and the highest roughness parameter values Ra and Rmax are 6,172 ?m and 33,66 ?m in the AZ91D alloy obtained when a voltage of 5 V is applied. In addition, shot peening treatment can help to improve the anodizing layer’s properties. Shot peened specimens which are then anodized have a more even oxide layer with fewer pores.