Microstructure, hardness, and wear resistance of sputtering TaN coating by controlling RF input power

• TaN films with fibrous and columnar structure were produced under RF input power control during sputtering.
• Multilayer TaN coatings with sequentially staked of TaN layer with different features was realized.
• Tougher behavior and better wear resistance were evident for TaN multilayers.

Tantalum nitride (TaN) layers were manufactured with different microstructures through RF magnetron sputtering. Deposition input power of 75 to 150 W was used in fabricating TaN layers with various impingement energies for different structures. A fibrous layer formed near the coating substrate interface for single-layer TaN films because of random stacking of atoms at early stage deposition, following which a compact columnar structure formed. The grain size and surface roughness decreased simultaneously with the input power. The hardness and Young's modulus for a single TaN layer deposited at 150 W were approximately 26.0 and 237.1 GPa, respectively. For single-layer TaN coatings, a compact structure and higher hardness were more beneficial to the wear resistance of the 150 W deposited TaN film than for those deposited at other input powers. Further study on TaN coatings in multilayer systems was conducted to examine protective behaviour. The multilayer TaN coatings consisted of alternately stacked TaN layers fabricated at input powers of 75/150 and 100/150 W. Characteristics of the multilayer coatings, including surface morphology, hardness, Young's modulus, and tribological behaviour, were investigated. The structure of the multilayer TaN films comprised a mixture of the single-layer TaN films. An average hardness between those of crystalline and featureless TaN layers was expected. However, tribological behaviour analysis revealed narrower wear scar and limited film failure on the wear track for multilayer systems. Consequently, the multilayer TaN systems showed greater durability than did the single-layer TaN films.