EFFECT OF SHOT PEENING WITH VARIATION OF TIME AND ANODIZATION ON MECHANICAL PROPERTIES AND CORROSION RATE OF MAGNESIUM ALLOY AZ91D AS BIODEGRADABLE ORTHOPEDIC IMPLANT

• Main Author: Abdul Rahman, Alif
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67958
• Institution: Institut Teknologi Bandung

The need for implants in Indonesia reaches 120 thousand per year and the metal alloys used as implants today are Ti, SS, and Co-Cr-Mo alloys. These alloys require a second operation for implant removal and can cause stress shielding and bone inflammation. Magnesium alloys have similar mechanical properties to natural bone and can be a biodegradable implants. Its weak corrosion resistance in a physiological environment is a weakness of magnesium alloys. Anodization is a method to produce a stable oxide layer on the surface of an alloy. The anodization process itself can reduce various mechanical properties of magnesium alloys. Shot peening is a process that can increase the hardness and fatigue strength so that it can overcome the negative effects caused by anodization. The variation of shot peening time is 12, 20, 40, and 60 minutes. After the shot peening was done, anodization was carried out using a solution of 3M KOH + 1 M Na2SiO3 for 60 minutes with a voltage of 5 V. The characterization of the specimens used an Optical Microscope (OM) to observe the microstructure, Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) to observe the surface morphology of the specimen. The mechanical properties of the specimens were observed through surface roughness testing using the Surface Roughness Tester (SRT), the hardness of the specimens was observed using the Vickers Hardness Test (VHT), and the corrosion rate was tested through electrochemical tests on simulated body fluids in the form of Ringer Lactate. Shot peening treatment can reduce the crystal size and dissolve the phase of magnesium alloy AZ91D. With a shot peening duration of 12 minutes, the crystal size decreased by 17.54% and 13.85% in the sample with a shot peening duration of 60 minutes. Shot peening also causes changes in the structure of the phase. Shot peening treatment can increase the hardness of magnesium alloy AZ91D on the surface and provide a compressive layer within 0.6 cm from the sample surface. The highest hardness was obtained by samples with a shot peening duration of 60 minutes with a value of 106 HV on the surface. The roughness of the sample that has been shot peened increases when compared to as received with the highest Ra and Rz in the sample with a shot peening duration of 20 minutes of 15,678 and 71.405, the anodization treatment can reduce the roughness of the sample up to 45.5%. Shot peening treatment reduces corrosion resistance when compared to the sample as received. Samples with a shot peening duration of 12 minutes had the highest corrosion rate of 85.18 mm/y. Anodizing treatment is efficient to reduce the corrosion rate of samples that have been given shot peening treatment.