Surface morphology and mechanical properties of nanoscale TiAlN/SiNx multilayer coating deposited by reactive magnetron sputtering

TiAlN/SiNx multilayer and TiAlN monolayer coatings were prepared on cemented carbide tool and silicon wafer substrates by reactive magnetron sputtering deposition. The microstructure of the coatings was observed by atomic force microscopy (AFM) in the dynamic friction mode (DFM) and transmission electron microscopy (TEM) for the investigation of the relation between the topography and mechanical properties of the TiAlN and TiAlN/SiNx coatings. Vickers hardness testing, scratch testing and high-frequency linear-oscillation (SRV) friction testing were performed to study the mechanical properties of the coatings. Under optimized deposition conditions, the TiAlN/SiNx multilayer coating showed a higher hardness of about 3200 HV and better wear resistance than the TiAlN monolayer coating. These improvements in hardness and wear resistance were attributed to the introduction of a large number of TiAlN/SiNx interfaces formed between TiAlN and SiNx layers and the refinement of multilayer microstructure owing to the suppression of the TiAlN grain growth.