目的 提高电化学射流(Jet-ECM)加工纯铜工件的加工稳定性和表面质量，并分析材料去除机理。方法 采用基于磷酸基的酸性钝化电解液。该酸性钝化电解液采用磷酸为黏膜生成剂，乙醇为润湿剂，苯并三氮唑(BTA)为腐蚀抑制剂，醋酸铵和乳酸为表面氧化物去除剂。分别通过极化曲线，阻抗测试揭示磷酸溶液中黏膜层的生成机理，并通过循环伏安曲线(CV)对乙醇和BTA的反应机理进行研究。结果 提高磷酸浓度有利于形成厚实的黏膜层，提高表面质量。乙醇能够提高电解液的润湿性，促进电解产物的排出。同时乙醇在Jet-ECM加工过程中具有钝化效果，提高了表面质量。腐蚀抑制剂BTA能够吸附在工件表面，形成保护膜，同时参与反应，形成Cu(I)-BTA聚合物保护膜，通过这两种成膜机理，对铜工件表面形成有效保护。采用该酸性钝化电解液用于金属铜的Jet-ECM加工，加工后孔中心区和孔边缘区的表面粗糙度分别为14.5 nm和157 nm。相比常规NaNO3电解液以及纯磷酸电解液，该新型电解液能够有效避免絮状沉淀的产生，显著提高表面质量。结论 采用基于磷酸基的酸性钝化电解液，能够提高电化学射流加工纯铜工件的加工稳定性和表面质量。该研究有助于进一步揭示Jet-ECM加工中的电化学去除机理，提高无应力加工方法的加工质量和加工稳定性。

To improve the machining stability and surface quality of jet electrochemical machining (Jet-ECM), and analyze the material removal mechanism in Jet-ECM of copper (Cu), a novel kind of phosphoric acid passivation electrolyte was used in this paper. The novel electrolyte used phosphoric acid as a viscous film-forming agent, ethanol as a wetting agent, benzotriazole (BTA) as a corrosion inhibitor, ammonium acetate and lactic acid as surface oxide removers. The mechanism of viscous film formation was studied through the polarization curve and impedance tests, and the mechanism of ethanol and BTA were studied by cyclic voltammetry curve (CV). The research results showed that with the increase of phosphoric acid concentration, the viscous film could be effectively formed and the surface quality could be improved. Ethanol could improve the hydrophilicity of the electrolyte, which was beneficial for the discharge of products. At the same time, ethanol had a passivation effect that could improve the surface quality. The BTA protected the Cu surface through two ways:physical film and Cu(I)-BTA polymer film. The new acid electrolyte was used for Jet-ECM of Cu, and the surface roughness of the jet center area was reduced to 14.5 nm and the surface roughness of the stray corrosion area was reduced to 157 nm after machining. Compared with traditional NaNO3 electrolyte and pure phosphoric acid electrolyte, it could effectively avoid precipitation and significantly reduce the surface roughness of the jet center and the stray corrosion area. Acid passivation electrolyte based on phosphoric acid group is adopted, it can improve the processing stability and surface quality of pure copper workpiece machined by electrochemical jet. This study improves the surface quality and stability of stress-free machining methods and has great implications for the further understanding of the electrochemical removal mechanism in Jet-ECM of Cu.