An investigation on Preparation and Effects of Post Heat Treatment on Electroless Nanocrystalline Ni–Sn–P Coatings

In this study, the electroless Ni–Sn–P coatings with different amounts of Sn were deposited on copper substrates to study the properties of the as-plated and heat treated coatings, especially corrosion behavior in 10 wt% sulfuric acid. Surface composition, surface morphology, and a cross-section of the coatings were studied by Energy Dispersive Spectroscopy (EDS) and field emission electron microscope (FESEM) respectively. Structure and corrosion behavior of coatings were studied by X-ray diffraction (XRD) and electrochemical tests. Results showed that increasing in Sn content and changes in Ni and P content of the coatings led to the uniform and compact surface and changes within the structure of the coating. The coating with higher Sn content had the best corrosion behavior. Post heat treatment of nanocrystalline Ni–Sn–P coating resulted in better corrosion behavior, and the optimum heat treatment temperature was 350 °C.