Effects of Yb ³⁺ on the corrosion resistance and deposition rate of electroless Ni-P deposits

Ni-P alloy coatings were deposited with the addition of Yb ³⁺ in the electroless plating solution. The effects of Yb ³⁺ concentration on the corrosion resistance and deposition rate of electroless Ni-P coatings were investigated. The results showed that the addition of Yb ³⁺ could significantly improve the corrosion resistance of the coatings. When increasing Yb ³⁺ up to 0.20 g L ^-1 , the corrosion potential E _corr of the electroless Ni-P coating in 3.5% NaCl solution increased from -0.381 to -0.08 V, and the corrosion current density I _corr decreased from 7.36 to 0.62 μA cm ^-2 . At 0.20 g L ^-1 Yb ³⁺ , the coating could be as long as 960 h free of corrosion in the neutral salt spray. In addition, the deposition rate can also be accelerated by Yb ³⁺ addition. The mechanisms of Yb ³⁺ influencing on the corrosion resistance and deposition rate of electroless Ni-P coatings were discussed.