STUDY OF THE EFFECT OF SHOT PEENING AND ANODIZATION WITH TIME AND VOLTAGE VARIATION ON THE CORROSION RESISTANCE OF MAGNESIUM ALLOY AZ91D AS BIODEGRADABLE IMPLANT

• Main Author: Satrio Dwi Cahya, Muhammad
• Format: Final Project
• Language: Indonesia
• Subjects: Metalurgi
• Online Access: https://digilib.itb.ac.id/gdl/view/51400
• Institution: Institut Teknologi Bandung

The demand for implant plates in Indonesia increased to 80-100 thousand in 2017. Implants can be used to overcome the effect of atherosclerosis and bone fracture. Implant which is made of metal has some advantages, such as good mechanical strength and good fracture toughness. But, most of the metal implants have to be removed from the body by a second surgery after placement in order to prevent long term side effects. Another alternative to prevent a second surgery is the utilization of biodegradable implant, such as magnesium implant. Besides being biodegradable, magnesium also has a good biocompatibility. However, magnesium has a high corrosion rate, so that it will corrode and break down directly before the healing process is finished. In order to improve the corrosion resistance of magnesium alloy, shot peening and anodization are applied. The alloy which is used as the subject of this research is AZ91D alloy. The first step in this research is the preliminary experiment. Sample of AZ91D alloy is cut into size (1x1x1) cm and shot peening will be applied on the specimen. The three time variations for shot peening are 4, 7, and 10 minutes. After shot peening, the hardness of AZ91D alloy is measured by Vickers Hardness Testing machine. After that, a literature study about mechanical properties and microstructures of shot peened AZ91D alloy is conducted. Besides that, a literature study about anodization of AZ91D alloy is also conducted in order to predict the effect of shot peening and anodization combination on the mechanical properties and corrosion resistance of AZ91D alloy. The observed variables from anodization are anodization time, voltage, and current density. The result from a preliminary experiment and literature study shows that the hardness and fatigue resistance of AZ91D increased by shot peening. As Almen intensity increases, the fatigue resistance of AZ91D also increases until it reaches a maximum value. When Almen intensity exceeds a certain value, the fatigue resistance value drops. Aside from that, it has been proved that anodization can improve corrosion resistance. When anodization duration increased, the anodization film thickness is also increasing until a certain value. Anodization film thickness is increasing rapidly as anodization current increased. Therefore, anodization current should be high at the beginning of the anodization process and low at the end of the anodization process. Besides that, the anodization voltage is also affecting anodization film properties. The applied voltage should be optimized to a level where it can provide adequate thickness and a low level of porosity of the anodization film so that it can improve the corrosion resistance of AZ91D alloy.