Investigation of the microhole arrays generated by masked jet electrochemical machining with polyaluminum chloride electrolyte

Abstract

Zirconium (Zr) alloy is a passivating metal with excellent general properties. The oxide films present on passivating metals make them resistant to corrosion by strong acid and alkali solutions, high-temperature water, and liquid metals. However, microfabrication of Zr alloy metal structures using existing machining methods suffers from low machining efficiency and poor machining quality. Electrochemical machining has advantages for processing Zr alloy metal microstructures. This study sought to evaluate the feasibility of masked jet electrochemical machining with a new electrolyte, polyaluminum chloride (PAC) of a microhole array in a Zr702 sheet. The dissolution behavior of Zr702 was analyzed with different concentrations of NaNO3, NaCl, and PAC. The electrochemical corrosion mechanism of Zr702 by using PAC was elucidated. A 2D model was established to analyze the evolution process of the sectional profiles of the microholes. Then, the effects of the main processing parameters were studied, and multifactor interaction response surfaces were analyzed. After optimizing the parameters, a high-quality microhole array was obtained with an average hole diameter of 152.11 μm, an average depth of 76.13 μm, a depth/diameter ratio of 0.501, a lateral corrosion coefficient of 2.023, a diameter variation coefficient of 1.71, and a depth variation coefficient of 2.87.