Synthesis and mechanical properties of TiAlCxN1−x coatings deposited by arc ion plating

Quaternary TiAlCxN1−x coatings were deposited on steel substrates (SKD11) by arc ion plating (AIP) method using TiAl (Ti/Al atoms = 1) alloy target in CH4/(CH4 + N2) gaseous mixture. The carbon content of TiAlCxN1−x coatings was increased linearly with increasing CH4/(CH4 + N2) gas flow rate ratio. The microhardness of TiAlCxN1−x coatings increased from 22 GPa of (Ti,Al)N to 41 GPa of TiAlC0.48N0.52 coatings as the carbon content increased. The TiAlC0.48N0.52 coatings showed largely increased hardness with nearly maintaining the oxidation resistance of (Ti,Al)N coatings. The change of hardness with the carbon content had a relationship with the residual stress. In addition, the average friction coefficient of the TiAlCxN1−x coatings remarkably decreased with increasing carbon content. In this work, the microstructure and mechanical properties of the TiAlCxN1−x coatings were systematically investigated.