Syntheses and Mechanical Properties of Ti-Al-Si-C-N Coatings by a Hybrid Coating System

In this work, the Ti-Al-Si-C-N coatings were synthesized on Stainless steel and Si wafer by a hybrid coating system, where arc ion plating (AIP) technique was combined with a magnetron sputtering technique. Also, the effect of Si content on the microstructure and mechanical properties of Ti-Al-C-N coatings were systematically investigated. The Ti-Al-Si-C-N coatings characterized by a nanocomposite comprising nano-sized Ti-Al-C-N crystallites embedded in amorphous Si3N4 phase. The micro-hardness values of Ti-Al-Si-C-N coatings were largely depended on Si content and the micro-hardness value of Ti-Al-Si-C-N coatings significantly increased from 38Gpa of Ti-Al-C-N coatings to approximately 56 GPa with the addition Si content of 9.8 at.%. The enhanced hardness values of Ti-Al-Si-C-N coatings were explained with the refinement of Ti-Al-C-N crystallites and composite microstructure characteristics by the percolation of amorphous Si3N4/SiC phase. The average friction coefficient of Ti-Al-Si-C-N decreased from 0.6 of Ti-Al-C-N to 0.23 with increasing the Si content up to 15.3 at. %. The decreased friction coefficients of Ti-Al-Si-C-N coatings was elucidated by the formation of SiO2 or Si(OH)2 layer known as self-lubricant materials.