Effect of N2/Ar gas flow ratios on the nitrided layers by direct current arc discharge

Nitrided layers were prepared on titanium substrates by direct current (DC) arc discharge technique. The effect of nitrogen to argon flow ratios on the microstructures and mechanical properties of the samples was investigated. The X-ray diffraction results show that the surfaces of the layers consist mainly of TiN and a very little TiN0.3 (101) under the condition of nitrogen/argon gas mixture. A strong TiN (200) preferential orientation in nitrided layers can be seen. With increasing the nitrogen concentration ratio in nitrogen/argon gas mixture, the density and size of TiN dendrites in the nitrided layers, and the hardness and wear resistance of the layers enhanced significantly.