Microstructural characterization and mechanical properties of nitrided layers on aluminum substrate prepared by nitrogen arc

The present work explores the feasibility of nitrided layers prepared on the aluminum substrate by nitrogen arc discharge at atmospheric pressure. The composite nitrided layers consisted of AlN and aluminum solid solution phases were obtained by the nitrogen arc discharge at the different nitrogen to argon gas flow ratios. The effect of the nitrogen gas contents in the gas mixture on microstructures, hardness and wear resistance of the nitrided layers was investigated. There were lamellar microstructures of AlN and aluminum solid solution distributed alternately at the upper portion of the nitrided layer and the AlN dendrites mainly distributed at the middle and bottom of the layer. It was found that the nitrided layers had high hardness, good wear resistance. With increasing the nitrogen to argon gas flow ratios, the thickness, hardness and wear resistance of the layers were enhanced significantly.