Effect of Si addition on microstructure and mechanical properties of Ti-Al-N coating

Ti-Al-N coatings are widely used to prevent the untimely consumption of cutting tools exposed to wear. Increasing requirements on high speed and dry cutting application open up new demands on the quality of wear-protective quaternary or multinary Ti-Al-N based coating materials. Here, we investigated the microstructure and mechanical properties of Ti-Al-N and Ti-Al-Si-N coatings deposited on cemented carbide by cathodic arc evaporation. The formation of nanocomposite nc-TiAlN/a-Si3N4 structure by incorporation of Si into Ti-Al-N coating causes a significant increase on hardness from similar to 35.7 GPa of Ti-Al-N to similar to 42.4 GPa of Ti-Al-Si-N. Both coatings behave age-hardening during thermal annealing, however Ti-Al-Si-N coating reveal better thermal stability. Therefore, the improved cutting performance of Ti-Al-Si-N coated inserts is obtained compared to Ti-Al-N coated inserts. (C) 2010 Elsevier Ltd. All rights reserved.