Investigation on high-phosphorus electroless Ni-P plating technology of stainless steel

The high-phosphorus electroless Ni-P plating was coated on the surface of stainless steel. Five parameters, which have much effect on coating quality, were chosen to optimize the high-phosphorus electroless Ni-P plating technology in L-16(4(5)) orthogonal test. By means of x-ray diffraction, and scanning electron microscopy, the morphologies and phase structures of coating were analyzed. Furthermore, the mechanical properties of coating were studied by micro-hardness tester and universal friction-wear testing machine. The results reveal that the optimal technical parameters are as follows: 20 g.L-1 for NiSO4, 23 g.L-1 for NaH2PO2, 15 g.L-1 for C6H5O7Na3 center dot 2H(2)0, 8 g.L-1 for H2N-CH2-COOH, 10g.L-1 for CH3COONa, 7 g.L-1 for C4H6O4, with PH value of 4.6, which leads to perfect coating quality. Besides, the P content is 11.64 wt.%, i.e. a high-P coating. The micro-hardness of the coating is 550.67 HV and the wear loss, 4.7x10(-3) g. The thermal shock test suggests that between coating and matrix exist a perfect cohesion, which is due to the homogenous and compact coating, with an amorphous structure, under the condition of the optimal technical parameters.