Wear 271 (2011) 2890–2898 Contents lists available at ScienceDirect Wear j o ur nal ho me p age: www.elsevier.com/locate/wear The influence of ductile interlayer material on the particle erosion resistance of multilayered TiN based coatings Brian Borawski a,c,∗ , Judith A. Todd a , Jogender Singh b,c , Douglas E. Wolfe b,c a Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, United States b Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, United States c Applied Research Laboratory, The Pennsylvania State University, University Park, PA 16805, United States a r t i c l e i n f o Article history: Received 6 January 2011 Received in revised form 24 May 2011 Accepted 6 June 2011 Available online 13 June 2011 Keywords: Erosion resistant coating Multilayered coatings Interlayer material Titanium nitride a b s t r a c t The effect of interlayer material on the particle erosion performance of titanium nitride (TiN)-based, magnetron-sputtered, physical vapor deposited (MS-PVD) coatings for the protection of AM355 steel components, subjected to hard particle erosion, was investigated. TiN-based coatings with interlayers of Ti, Zr, Hf, and Nb were compared for hard particle erosion resistance against angular alumina and glass bead mediaat velocities of 75 m/s and 180 m/s. In this study, high values of Vickers microhardness correlated with poor erosion performance. The TiN/Zr multilayer coatings exhibited the worst durability for all erosion conditions, even though they were the hardest coatings and had the lowest erosion rates (mass loss) early in life against glass bead media. The TiN/Nb multilayer coatings provided the best durability in most conditions. Although the TiN/Ti coatings showed best durability against the alumina particles, this difference was small and may be attributed to the relative total thickness of the coatings. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Finnie [1] reviewed the work of Wellinger et al. [2–6], who identified a material’s hardness as a key parameter in erosion performance. In the case of ductile materials, Finnie [7] notes cases where plastic flow stress may also be a key parameter gov- erning erosion performance. Tilly [8] discovered that although higher hardness increased the erosion resistance of ductile mate- rials, it decreased the erosion resistance of brittle materials. More recently, coating architecture and toughness have been recognized as important factors, particularly the erosion and wear benefits of incorporating a ductile layer or interlayers in ceramic-based coat- ings [9–15]. The change in multilayer coatings system properties such as hardness, adhesion, energy absorption, and fracture tough- ness have been studied as a function of the number, thickness and materials comprising the ductile interlayers [16–20]. In this study, the effect of the ductile interlayer materials, Ti, Zr, Hf, and Nb, on the hard particle erosion resistance of multilayer coatings is inves- tigated to provide insight into the coating properties governing the erosion of multilayer coatings. Ductile materials have the ability to blunt crack tips and redis- tribute stress via plasticity mechanisms. In layered coatings, as ∗ Corresponding author at: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, United States. Tel.: +1 814.865.4523; fax: +1 814.863.7967. E-mail address: bxb229@psu.edu (B. Borawski). cracks approach interfaces, they may be redirected along the inter- faces, deflected at the interface, or stopped if there is a significant change in the strain energy release rate, G [21–23]. He et al. showed that crack deflection depended on the interfacial tough- ness, residual stress fields, and material fracture toughness [24,25]. For multilayered coatings, crack deflection along or at interfaces may provide inherent resistance to crack growth and potentially improve erosion performance; however, it may also cause prema- ture layer delamination. Increasing strength of multilayered coatings with increasing number of layers (i.e., decreased interlayer spacing) has been related to the Hall–Petch effect [26], where yield strength increases with decreasing grain size [26,27]. Kikuchi et al. [21] found that if two materials chosen for multilayer coatings had similar elas- tic properties, strengthening did not follow Hall–Petch behavior. This suggests that Hall–Petch strengthening in multilayer mate- rials requires a discrete change in elastic or plastic properties; agreeing with Koehler’s principles [28] for designing ultra-tough solids. In contact mechanics of laminate materials, the ratio of Hertzian contact stresses and flexural stresses depends on the ability of the “adhesive” layers (interlayers) to support the upper layers and transfer shear stresses. Chai and Lawn [29] identified multilayer configurations and material combinations for which the top (hard) layer of a multilayer laminate would fail at a higher load than that required for a hard monolith of equal thickness. They confirmed that a thinner hard layer or a thicker adhesive layer would be more likely to cause premature tensile failure at the underside of the 0043-1648/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2011.06.004