Mechanical properties of titanium nitride coatings deposited by inductively coupled plasma assisted direct current magnetron sputtering

Abstract

TiN coatings were deposited on M2 high speed steels by an inductively coupled plasma (ICP) assisted sputtering technique. The structure and mechanical properties such as hardness, Young’s modulus, and adhesion strength of the coatings were investigated. For ICP sputtering, rf power was applied using a rf coil installed in the deposition chamber. Prior to the deposition, the substrate was pretreated by ICP in the same deposition chamber in order to improve the adhesion strength of the coating. The ICP power was varied from 0 to 600 W, and the hardness of the coatings was found to increase with increasing ICP power. When the ICP power was larger than 300 W, the hardness of TiN was above 6000 HK0.01, which was one of the highest hardness values of TiN reported in the literature. The adhesion strength of the coating was also high enough for industrial applications. The results from structural investigations indicated that the high hardness is a property of the dense structure as well as the high compressive residual stress of the coatings.