哈氏合金C-276电抛光中抛光液的失效分析

目的哈氏合金C-276带材被广泛用作第二代高温超导体YBCO的金属衬底,其表面抛光质量(粗糙度Ra)要求极为严格。为了保证抛光质量就要有效控制电化学抛光液,对抛光液的变化及失效与否进行分析。方法以哈氏合金C-276带材为研究对象,采用非接触式电化学抛光方法,使用扫描电镜、原子力显微镜、金相显微镜、微波等离子体原子发射光谱仪等仪器设备,阐明了抛光液中H_3PO_4和H_2SO_4等主要成分的作用及工艺要求,并测定单位体积抛光液在一定时间内通过电量(Ah/L)后,H_3PO_4、H_2SO_4含量及Ni、Cr、Mo等金属离子浓度。结果当H_3PO_4、H_2SO_4含量分别在775~1013 g/L、318~451 g/L范围内,Ni、Cr、Mo三种金属离子质量浓度分别小于7.3、2.7、3.4 g/L时,C-276带材表面的粗糙度才能满足工艺要求Ra1 nm(5μm×5μm)。结论通过对电化学抛光液中的H_3PO_4、H_2SO_4、添加剂、金属离子浓度等有效控制,采用非接触式电化学抛光,实现了千米级哈氏合金第二代高温超导带材的连续生产,并且表面粗糙度Ra1 nm。

Failure Analysis of Electrolyte in E-polishing Process of Hastelloy Alloy C-276

Hastelloy alloy C-276 strip has been widely used as metallic substrate of YBCO second generation high temperature su-perconductor. The alloy is subject to strict requirements regarding surface polishing quality (roughness Ra in the work). Electrochemical polishing agent shall be controlled effectively and analyzed for variation and failure to guarantee polishing quality. With C-276 strip as object of study, non-contact electrochemical polishing method as well as instruments including SEM, AFM, metallographic microscope and microwave plasma atomic emission spectrometer were used. Functions and process requirements of main components including H3PO4 and H2SO4 in polishing agent were elaborated. Content of H3PO4 and H2SO4, and ionic concentration of Ni, Cr and Mo were measured after unit volume polishing agent passes through electric quantity in certain period (Ah/L). C-276 strip surface roughness will not meet the process requirements Ra <1 nm (5 μm× 5 μm) unless content of phosphoric acid and sulfuric acid fell within 775~1013 g/L and 318~451 g/L, ionic concentration of Ni, Cr, Mo was<7.3 g/L, 2.7 g/L, 3.4 g/L, respectively. Non-contact electrochemical po- lishing is used to achieve continuous production of the second-generation high-temperature superconducting tapes of kilometric Hastel-loy based on effective control of sulfuric acid, phosphoric acid, additives and metal ion concentration in electrochemical polishing agent. The surface roughness Ra is < 1 nm.