Influence of chamber pressure variations of plasma nitriding on surface hardness and micro structure of Al 6061

Abstract

Aluminium 6061 is a material that is widely applied in industrial and automotive parts. The corrosion resistance and surface hardness of Al 6061 can be improved by using plasma nitriding. Plasma nitriding is the process of treating the surface of a material by inserting nitrogen in the material through the plasma, i.e. nitrogen gas was converted in the form of plasma before being inserted into the material. This research was conducted using experimental research methods by directly observing the plasma nitriding process. This research used aluminium alloy 6061 as a specimen, variations in chamber pressure of plasma nitriding 100 mTorr, 200 mTorr, and 300 mTorr, constant temperature of 150 °C, constant power input of 40 watts, and holding time for 2 hours. Hardness testing was carried out using a micro-Vickers hardness tester, whereas microstructure testing used SEM (Scanning Electron Microscope) and EDAX. Experimental results showed the highest surface hardness value of Al 6061 was 276.5 VHN. This condition occurred at a chamber pressure of 200 mTorr, temperature of 150 °C, the input power of 40 watts and a holding time of 2 hours. Based on composition and microstructure analysis using EDAX and Scanning Electron Microscope shown that the lowest surface hardness 179.4 VHN had a nitrogen content of 1.225% and this occurred at a chamber pressure of 300 mTorr.