Effect of Ti interlayer thickness on mechanical properties and wear resistance of TiZrN coatings on AISI D2 steel

• Published in: Surface & coatings technology 2020-07, Vol.394, p.125690, Article 125690
• Main Authors: Lin, Yu-Wei, Chih, Po-Chun, Huang, Jia-Hong
• Format: Article
• Language: English
• Subjects: Adhesive strength; Adhesive wear; Chromium molybdenum vanadium steels; Interlayers; Mechanical properties; Protective coatings; Residual stress; Stored elastic energy; Thickness; Ti interlayer; Titanium; TiZrN coating; Tool steels; Wear resistance
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.125690

In the tool industry, adding a soft metallic interlayer to enhance the adhesion of hard coatings is a common practice. This study investigated the effect of Ti interlayer thickness on the residual stress, adhesion strength and wear resistance of TiZrN coatings. The feasibility of using stored elastic energy as an index of wear resistance of the coatings was also studied. The effect of Ti interlayer thickness was evaluated by comparing the mechanical properties of TiZrN films with different Ti interlayer thickness, ranging from 50 to 250 nm. The results showed that the increase of interlayer thickness from 50 to 250 nm reduced the stress of the TiZrN coatings from −5.67 to −3.75 GPa. The optimal Ti interlayer thickness to enhance the adhesion strength of the TiZrN coatings with about 2 μm thickness on D2 steel was 150 nm; however, the adhesion was insignificantly improved compared with the specimen without interlayer. Introducing 250 nm Ti interlayer could slightly increase the wear resistance of the TiZrN coating about 16%, but the adhesion strength of the coating decreased about 6%. The insignificant improvement on mechanical properties and wear resistance of the TiZrN coatings by the Ti interlayer were mainly attributed to the high residual stress of TiZrN top layer. For the coatings with high residual stress (>−4.0 GPa), the stress relief by adding a metal interlayer is limited and insufficient to enhance adhesion strength or wear resistance. Other approaches that can directly lower the intrinsic growth stress in hard coatings may be more effective. •The stress of TiZrN coatings decreased with increasing Ti interlayer thickness.•The residual stress in TiZrN coatings was relieved by both Ti interlayer and D2 substrate.•The extent of stress relief in TiZrN by Ti interlayer was not substantial.•Adhesion and wear resistance were insignificantly improved by adding Ti interlayer.•The limited function of Ti interlayer was mainly due to high residual stress in TiZrN coating.