Performance and Microstructure Analysis of 99.5% Aluminium Coating by Thermal Arc Spray Technique

Thermal arc spray aluminium coating is widely used in recent years as a protective coating due to its capability to withstand high temperature and cost effective process. It has been utilized by many industrialists in oil and gas sector, where most of the applications are in atmospheric condition. Organic coating could fail prematurely and result in corrosion progression from coating failure. This paper will discuss the overall framework of experiments to justify the performance of thermal arc spray aluminium coating. In this research 99.5% aluminium was used as the coating material in wire form of 2.3 mm diameter using wire arc spray method. Six samples were prepared with different thickness of coating from 200 to 400 microns. Mechanical tests such as Pull-off Test and Bend Test were performed to evaluate the coating performance. The tests indicated that all samples had passed the minimum requirement with an average of 10 MPa for Pull off Test and no crack appeared in Bend Test. Hardness Test and Surface Morphology Analysis were also performed with coating thickness ranged between 350-400 microns to inspect and evaluate the coating properties. The hardness test showed an average value of 209.7 HV. Surface morphology analysis using FE-SEM indicated low porosity structures and high content of oxide. Thus, from the overall results and analysis it was found that the thermal arc spray can perform coating duty effectively. Further research may be conducted to explore more on the potentials of thermal arc spray aluminium coating such as the analysis on different coating thickness and coating materials.