Experimental Investigation on Chemical Mechanical Polishing of ZA27 Alloy Considering Galvanic Corrosion at Zn/Al Interface

To improve the surface integrity of ZA27 alloy, a method of chemical mechanical polishing (CMP) considering the galvanic corrosion at the Zn/Al interface is proposed to treat the surface of ZA27 alloy. Firstly, the electrochemical experiment is carried out to study the influence of the pH, H2O2 concentration, and glycine concentration on corrosion potential between zinc and aluminum. Then the Taguchi method integrated with grey relation analysis and fuzzy inference are used to optimize the CMP parameters of ZA27 alloy. Finally, the prediction model of the MRR and surface roughness Ra is established using the mathematical regression analysis method. The experimental results showed that the minimum zinc-aluminum corrosion potential difference is 14 mV when the pH is 10, H2O2 concentration is 1 wt%, and glycine concentration is 0.4 wt%. The optimum CMP parameter is the polishing pressure of 34 kPa, the polishing plate's rotational speed of 70 rpm, and the abrasive particle concentration of 15 wt%. After polishing with the optimum CMP parameter, the MRR is 242 nm/min, and the surface roughness Ra is 13.91 nm. This study demonstrates that the CMP considering the galvanic corrosion at the Zn/Al interface is an effective method for treating ZA27 alloy surface.