Abstract
To improve the adhesion strength between the film and stainless steel substrate, decrease porosity of the film, and enhance the corrosion resistance of electroplated Pd-Ni alloy film on stainless steel. Methods Pd-Ni film was prepared on 316L stainless steel according to processes of anodic electrolytic activation-nickel strike and cathodic activation pretreatment. Physical properties such as surface morphology, micro-hardness, porosity and adhesive strength of the films prepared by the two processes were comparatively studied, and corrosion resistance and erosion-corrosion resistance of the Pd-Ni films by two pretreatments were measured by corrosion weight loss test, polarization measurement and scanning electron microscope. Results Compared with the Pd-Ni alloy film prepared after cathodic activation (Pd-Ni film), the Pd-Ni alloy film prepared after anodic electrolytic activation-nickel strike (shorted as Ni/Pd-Ni film) had the same surface morphology and elementary composition. The micro-hardness of the Ni/Pd-Ni film was 373.8HV, porosity was 1.33 cm–2, and adhesive strength was 12.94 MPa; while the micro-hardness of the Pd-Ni film was 351.4HV, porosity was 3.33 cm–2, and adhesive strength was 1.31 MPa. The corrosion rate of the samples plated with Ni/Pd-Ni film in both 20 wt.% H2SO4 and 20 wt.% H2SO4 + 0.001 mol?L–1 Cl– solutions at 80 ℃ was about 1/3 that of the sample plated with Pd-Ni film. At 80 ℃, 20 wt.% H2SO4 + 100 g?L–1 SiO2 particles with 1200 r/min stirring, the lifetime of Ni/Pd-Ni film was about 4 times that of the Pd-Ni film. Conclusion Physical properties of the Pd-Ni film can be improved by anodic electrolytic activation-nickel strike pretreatment process, especially the adhesion strength increases by almost an order of magnitude. The corrosion resistance and erosion-corrosion resistance of the Ni/Pd-Ni film plated samples are obviously increased.
Key words
316L stainless steel; palladium-nickel alloy film; nickel strike; adhesion strength; corrosion resistance; erosion-corrosion
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LI Yang, ZHANG Hui-zhong, ZUO Yu.
Improvement of Corrosion Resistance of Electroplated Pd-Ni Alloy Film on 316L Stainless Steel by Anodic Electrolytic Activation-Nickel Strike Pretreatment[J]. Surface Technology. 2016, 45(12): 147-153
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Funding
National Science and Technology Support Project (2012BAE04B01)