Effect of Tin Addition on the Properties of Electroless Ni-P-Sn Ternary Deposits

Abstract

In this study, the ternary Ni-P-Sn alloy coatings were prepared using electroless plating, and the effect of tin element on amorphous formation and anticorrosive properties of deposits in different corrosion medium were investigated. The different tin contents in deposits could be obtained by adjusting the amount of NaSnO₃·3H₂O in plating bath. The X-ray results indicate that the small amount of tin addition can improve the formability of the amorphous phase. At the same time, the hardness of deposit decreases and the crystalline temperature shifts to lower temperature with increasing amount of Sn. The electrochemical corrosive experiments of deposits resulted that the addition tin improves the anticorrosion property in 3.5 mass% NaCl solution, but reduces the anticorrosion ability in sulfuric acid solution.