Effect of TiC Content and TaC Addition in Substrates on Properties and Wear Behavior of TiAlN-Coated Tools

The present paper reports a new way to improve the wear resistance of coated carbide tools by increases in TiC content and the addition of TaC in substrates. The results suggest that the average grain size of the substrate increased with the increases in TiC (0–14 wt.%) content, and the hardness of the TiAlN coating deposited on the substrate exhibits a similar trend. In addition, the adhesion strength of the TiAlN-coated carbide increases with increasing TiC content, which can be attributed the formation of the (Ti,W)C phase and the similar hardness of the substrate and coating. The addition of TaC into the substrates inhibits the grain growth and thereby causes the hardness and adhesion strength of the TiAlN coatings to improve from 24.6 GPa and 16.7 N to 30.1 GPa and 17.3 N, respectively. In turning tests, the TiAlN coating deposited on the substrates with the TaC addition achieved the best wear resistance in turning stainless steel because it possessed the highest substrate and coating hardness and sufficient adhesion strength. However, the TiAlN coating deposited on the substrates with a higher TiC content shows the better wear resistance in turning titanium (TC4), which can be attributed to it having the highest adhesion strength.