电镀宽范围Re含量Ni-Re合金工艺研究

控制镀层中Re含量,获得较宽Re含量范围的Ni-Re合金镀层,可为单晶合金的高温防护提供技术支持。研究了Ni-Re合金电镀体系中镀液组分及电镀工艺条件对镀层外观、Re含量及电流效率的影响,得到最佳电镀工艺条件为电流密度Jc4~5 A/dm^2,温度60~70℃,pH=5;在该工艺条件下,保持镀液中柠檬酸与镍离子摩尔比为1.0,调整镀液中镍离子浓度(30~450 mmol/L),得到Re含量在16%~98%(质量分数)的Ni-Re合金镀层,并研究了镍离子对Re沉积的催化作用及Re含量对合金镀层微观结构的影响。结果表明:镍离子浓度为240mmol/L时对Re沉积催化效果最好,此时Re的析出电位正移40 m V,Re沉积电流效率达到66. 9%,JRe=30. 06m A/cm^2,Ni-Re合金镀层中Re含量≤43%时,镀层微观表面平整细致,其XRD谱衍射峰角度与纯镍相近,形成了以Re为溶质、Ni为溶剂的置换固溶体的晶体结构,随着合金镀层中Re含量的进一步增加,合金镀层向非晶态转变,在Re含量≥52%时,Ni-Re合金转化为非晶态镀层。

Study on the Electroplating Process of Ni-Re Alloys with Re Content in Wide Range

The Ni-Re alloy coatings with Re content in wide range were prepared by controlling the Re content in coatings,which could provide technical support for high-temperature protection of single crystal alloy. The effects of plating composition and electroplating conditions in Ni-Re alloy plating systems on the Re content,appearance and current efficiency of the coatings were studied,and the optimum process conditions were obtained: current density Jcof 4-5 A/dm^2,temperature of 60-70 ℃,pH = 5. Under the process conditions,with maintaining a molar ratio of citric acid to nickel ion in the plating solution of 1.0 and adjusting the nickel ion concentration in the plating solution( 30-450 mmol/L),the Ni-Re alloys with Re content in an amount of 16% to 98% were obtained. Meanwhile,the influence of nickel ion concentration on the catalytic action of Re deposition and the influence of Re content on the structure of alloy coating were analyzed. Results showed that 240 mmol/L Ni ions had the optimal catalytic effect on the Re deposition. The precipitation potential of Re was shifted by 40 m V,and the deposition current efficiency of Re reached 66.9%,JRe= 30.06 m A/cm^2. When the Re content of Ni-Re alloy coating used as high temperature oxidation resistant coating was ≤ 43%,the microscopic surface of the obtained coatings was smooth and detailed,and the XRD diffraction peaks were similar to those of pure nickel,indicating that the coating possessed a crystal structure of the replacement solid solution with Re as the solute and Ni as the solvent. With the further increase of Re content in the coating,the coating changed into amorphous state. When the Re content was ≥ 52%,the Ni-Re alloy was converted into amorphous coating thoroughly.