STUDY ON CORROSION PROPERTIES OF PLASMA NITRIDED PURE ALUMINIUM

In this research plasma nitriding of pure aluminium and effect of iron elemental alloy on the formation and growth of aluminium nitride was investigated. also corrosion properties of formed ain were investigated after preparation, the samp les were plasma nitrided at 550 c, for 6, 9 and 12 h and a gas mixture of 25%h2 -75%n2. the microstructure and phases analysis were investigated using scanning electron microscopy and x-ray diffraction analysis. moreover corrosion resistance of samples was investigated using polarization techniques. the results showed that only a compound layer was formed on the surface of samples and no diffusion zone was detected. dominant phase in compound layer was ain. scanning electron microscopy results showed that nitride layer has particulate structure.these nitrided particles have grown columnar and perpendicular to the surface. it was also observed that the existence of iron in the samples increases the nitrogen diffusion, thus growth rate of irun containing nitrides are higher than the others. corrosion tests results showed that formation of an aluminium nitride layer on the surface of aluminium decreases the corrosion resistance of aluminium significantly. this is due to elimination of surface oxide layer and propagation of cracks in the formed nitride layer.