Residual stresses and tribomechanical behaviour of TiAlN and TiAlCN monolayer and multilayer coatings by DCMS and HiPIMS

The deposition of ternary nitrides with the incorporation of carbon atoms into its structure has demonstrated to be a promising approach in the pursuit of wear resistant and self lubricating coatings. Firstly, both TiAlN and TiAlCN monolayers were deposited using direct current magnetron sputtering DCMS and high power impulse magnetron sputtering HiPIMS onto quenched and tempered AISI H11 tool steel to be used as references. Acetylene was used as a carbon precursor, producing DCMS and HiPIMS TiAlCN coatings with 9.0 and 21.7 at. C, respectively. Subsequently, TiAlN TiAlCN multilayers of various designs were also developed as follows 5 [10 500], 5 [50 500] and 5 [100 500] nm. Residual stresses of the coating systems were determined by X ray radiation utilising an ETA diffractometer with a Cu K amp; 945; radiation source applying the sin2 amp; 968; method. Additionally, residual stresses depth gradients of the substrate before and after the deposition of the coatings were determined in a LEDDI 8 circle diffractometer equipped with a W X ray tube and operated in the energy dispersive mode of diffraction. Great reduction of the compressive residual stresses in the coatings was observed after the introduction of carbon into the TiAlN coating structure, shifting from amp; 8722;1047 149 to amp; 8722;307 211 MPa for the DCMS and from amp; 8722;7035 1361 to 989 187 MPa for the HiPIMS coatings. In the multilayer coatings, compressive residual stresses increase along with the increment of the TiAlN interlayer. Additionally, residual stresses of the substrate in the near surface are dragged from low compressive stresses amp; 8722;218 61 to tensile stresses in the range of 1000 to 2000 MPa for all the DCMS substrate systems, a behaviour only presented in HiPIMS by the TiAlN monolayer. Wear coefficients of all the evaluated HiPIMS systems are notoriously lower than their DCMS counterparts. Compared to TiAlN, TiAlCN HiPIMS presented a lower coefficient of friction but a higher wear coefficient, which in turn was not reduced by the introduction of the multilayer systems. Finally, Scratch test and Rockwell C adhesion tests have shown higher adhesion of DCMS coatings than HiPIMS coatings, and a detriment of the monolayers adhesion by the implementation of TiAlN TiAlCN multilayer systems. The understanding of the residual stresses, both in the coating and in the substrate, and the way they affect the tribomechanical performance of the system coating substrate continues to be of great importance, especially for coatings deposited by new technologies such as HiPIMS and self lubricating coating