| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Thursday Sessions |
| Session TF-ThM |
| Session: | Advanced Protective Coatings/Stress Evolution, Nanostructure, and Physical Properties of Thin Films |
| Presenter: | David Surman, Kratos Analytical Inc. |
| Authors: | D.J. Surman, Kratos Analytical Inc. J. Counsell, Kratos Analytical Ltd., UK S.J. Coultas, Kratos Analytical Ltd., UK C. Moffitt, Kratos Analytical Inc. C.J. Blomfield, Kratos Analytical Ltd., UK A.J. Roberts, Kratos Analytical Ltd., UK |
| Correspondent: | Click to Email |
Super-hard inorganic multilayers have emerged in recent times as a distinct class of material, currently used in coatings of cutting tools for machining and in the aerospace industry. There has been significant effort to develop new coatings due to increased need for wear protection and friction reduction.
One such material we will discuss in this work is a TiN/CrN superlattice consisting of alternating TiN and CrN layers of nanometer-scale, deposited by the means of the reactive magnetron sputtering technique. This superlattice has been studied previously, examining performance properties under stress and temperature and the mechanisms of wear [1,2]. This material has been shown to have high oxidation resistance as well as superior mechanical properties. The hardness, high wear resistance and inertness of transition metal nitrides has been attributed to the unique bond structure. Typically 12-52 layers are deposited in a lattice with the extent of alloying, contamination, and roughening all critical to the performance of the lattice. Also, as the layers thin there are distinct changes in crystallinity and alloying affecting the tribological properties. As expected, deposition is difficult due to differences in the heat of formation of CrN and TiN – they each require different partial pressures of N2 to form stoichiometric coatings.
To explore the stoichiometry and the extent of alloying in a TiN/CrN superlattice, we have employed the traditional surface analysis techniques of ion etch depth profiling with XPS. It has been historically accepted that monatomic Argon will typically suffice for this process however in this presentation a comparison will be made between conventional monatomic Ar+ ions and the more recent cluster Arn+ ions. The choice of impinging ion will be discussed with respect to stoichiometry and blending as will the practicalities of the depth profiling experiment and analysis. A novel method is proposed for the analysis of these materials, free of erroneous results.
S. Gallegos-Cantú et al.,Wear, 330–331, 2015, pp 439–447.
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