Corrosion resistance, thermal diffusivity and mechanical properties of Ni-SiO${}_2$ nanocomposite coatings on a 316 stainless steel for heat exchanger applications

In this study, the effect of pure Ni and Ni-SiO${}_2$ nanocomposites coatings on corrosion, wear resistance and thermal conductivity of 316 stainless steel substrates was investigated with the purpose of extending the service life of 316 stainless steel plate heat exchangers. The nanocomposite coatings were developed by electroplating process in a Watts bath in different concentration values of SiO${}_2$ nanoparticles (10, 20 and 30 g l${}^{-1}$). Electrochemical corrosion was run to examine the corrosive performance of the coatings. The results showed that the Ni-SiO${}_2$ nanocomposite with concentration of 30 g l${}^{-1}$ had a higher corrosion resistance. A pin on disk wear test demonstrated that, in comparison to 316 stainless steel, the wear resistance of the Ni-SiO${}_2$ nanocomposite (30 g l${}^{-1}$) was up to 25% lower while its friction coefficient was almost the same. In addition, as measured via the laser flash method and differential scanning calorimetry, the thermal diffusivity and specific heat capacity of the sample respectively were found to be 32 and 43% lower in comparison to 316 stainless steel. Microhardness measurement via a Vickers microindenter showed that the microhardness of the Ni-SiO${}_2$ nanocomposite coating was more than three times higher than that of 316 stainless steel for all the reinforcement concentrations.