Microstructure controlling and properties of TiAlSiN nanocomposite coatings deposited by modulated pulsed power magnetron sputtering

Abstract

TiAlSiN nanocomposite coatings were deposited by modulated pulsed power magnetron sputtering (MPPMS) from TiAlSi targets with the Al/(Al+Ti) atomic ratios (x) of 0.25, 0.5 and 0.67. The targets were powered by average sputtering power of 1-4 kW under work pressure of 0.3 Pa with a nitrogen addition of 25%. All of the TiAlSiN coatings with a nitrogen content of 52.0at%~56.7at% possessed an nc-TiAlN/a-Si3N4/AlN nanocomposite structure. As x increased, the percentage of amorphous phases was increased, meanwhile the hardness of the coatings firstly increased and then decreased. In the TiAlSiN coating with x=0.5, a highest hardness of 28.7 GPa was detected. Improvement in average sputtering power could prompt the formation of a complete phase separation nanocomposite coatings with a constant grain size. With x=0.67 under average sputtering power from 1 kW to 4 kW, the hardness of the coatings increased from 16.4 GPa to 21.3 GPa. A low wear rate of about (0.13-6.25) ×10-5 mm3/(N·m) was detected in the TiAlSiN coatings with different Al contents as a function of the average sputtering power. An optimized wear resistance was identified in the TiAlSiN coatings deposited by MPPMS under average sputtering power of 2 kW at x=0.5.