Chemical Resistance Property of Electroless Deposited Ni–Sn–P Layers Having High Sn Content

Abstract

Chemical resistance of electroless-deposited nickel–tin–phosphorus (Ni–Sn–P) with a high Sn content (>30 at. %) and Ni–P layer on a cold-rolled commercial steel plate (SPCC) against a 5% aq solution of sodium hypochlorite (NaClO aq), which was used as a disinfectant solution, was examined. After immersion of Ni–Sn–P and Ni–P layers at 25 °C for 72 h to NaClO aq, the surface of the Ni–P layer showed a clearly corroded surface. On the other hand, the Ni–Sn–P layers were not corroded, so the Ni–Sn–P layers have chemical resistance properties against NaClO aq. The importance of the Sn addition to Ni layers for NaClO chemical resistance was confirmed. In addition, the chemical resistance of the Ni–Sn–P layers against hydrogen sulfide (H2S) gas and nitrogen acid (HNO3) vapor was also determined.