The morphology and mechanical properties of TiN/Ni–P–SiC hybrid coatings

The current trend of coating techniques involves composite coatings, such as multilayer or multiphase, which are expected to have tailor-made properties for some specific applications. In this study, a hybrid process that combined the composite electroless plating and plasma-enhanced chemical vapor deposition (PECVD) is proposed to improve the mechanical properties of TiN coated tool steel. Experimental results show that the apparent hardness of the TiN/Ni–P–SiC hybrid coatings increases with increasing content of SiC particles in electroless Ni–P interlayer and affects the TiN hardness value. This could be due to an effect of SiC particles on the coating growth of TiN and a high load carrying capability of Ni–P–SiC interlayer. In comparison with single TiN layer and TiN/Ni–P hybrid coating, a reduction in cracking and spalling for the TiN/Ni–P–SiC layer was observed during wear tests. Wear resistance was significantly improved due to the incorporation of SiC particles into electroless Ni–P interlayer, which increased hardness and adhesion of the coated TiN layer.