The Effect Of Corrosion Resistance Of Eletroplated Pd Based Alloy Films On 316L Stainless Steel By Anodic Electrolytic Activation-Nickel Strike Pretreatment Process

In this paper, the effect of corrosion resistance of eletroplated Pd based alloy films on 316L stainless steel by anodic electrolytic activation-nickel strike pretreatment process were studied. The optimum technological parameter was obtained by adhesion strength test, corrosion resistance test and scanning electron microscope. The results show that 1 min or above nickel strike can greatly improve the adhesion between the film and the stainless steel substrate, nickel strike for 1 min or so can effectively improve the corrosion resistance of the sample, but the corrosion resistance of the sample will decline when perform a longer time of nickel strike.Pd-Ni film was electrodeposited on 316L stainless steel after anodic electrolytic activation-nickel strike pretreatment process (Ni/Pd-Ni film). The Pd-Ni film was electrodeposited on 316L stainless steel after cathodic electrolytic activation (Pd-Ni film) as a comparison. The properties of the films such as microstructure, micro-hardness, porosity, adhesion strength, corrosion resistance and erosion-corrosion resistance were comparatively studied. Experimental results indicate that:the Ni/Pd-Ni film has higher micro-hardness, lower porosity than the Pd-Ni film, especially the adhesion strength increases dramatically from 1.3 MPa to about 13 MPa, increasing an order of magnitude. The corrosion resistance of the sampe plated with Ni/ Pd-Ni film in both 20 wt.% H2SO4 and 20 wt.% H2SO4+0.001 mol·L1 Cl-solutions at 80? or 102? is superior to the sample plated with Ni/Pd-Ni film; especially the erosion-corrosion resistance of the sampe plated with Ni/Pd-Ni film is significantly improved due to the higher micro-hardness, lower porosity and the excellent adhesion strength of the Ni/Pd-Ni film.Futhermore, Pd-Co film was electrodeposited on 316L stainless steel after anodic electrolytic activation-nickel strike pretreatment process (Ni/Pd-Co film). The Pd-Co film was electrodeposited on 316L stainless steel after cathodic electrolytic activation (Pd-Co film) as a comparison. The properties of the films such as microstructure, micro-hardness, porosity, adhesion strength, corrosion resistance and erosion-corrosion resistance were comparatively studied. Experimental results indicate that the Ni/Pd-Co film has higher micro-hardness, lower porosity and higher adhesion strength than the Pd-Co film. The corrosion resistance of the sampe plated with Ni/Pd-Co film in both 20 wt.% H2SO4 and 20 wt.% H2SO4+0.001 mol·L-1 Cl- solutions at 80? or 102? is superior to the sample plated with Ni/Pd-Co film; especially the erosion-corrosion resistance of the sampe plated with Ni/Pd-Co film is significantly improved, the useful life of the Ni/Pd-Co film is three times of the Pd-Co film in 80?,20 wt.% sulfuric acid solution with 100 g·L-1 SiO2 particals. The erosion-corrosion resistance of the sampe plated with Ni/Pd-Co film or Pd-Co film is better than the sampe plated with Ni/Pd-Ni film or Pd-Ni film in the same erosion-corrosion environment due to the higer micro-hardness of the Ni/Pd-Co film or Pd-Co film.