【作者】 商红武；

【导师】 安茂忠；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2008， 硕士

【摘要】 锌镍合金镀层是近20年发展起来的一种新型防护性镀层,具有高耐蚀性、低氢脆性、较好的可焊性和机械加工性,极具发展前景。本文在几种典型溶液配方的基础上,采用赫尔槽(250mL)实验,通过小槽电镀实验以及镀液性能、镀层性能测试,最后分析对比确定出最佳溶液成分及工艺条件。研究了主盐含量、添加剂、电流密度、温度及pH值对镀层镍含量及镀层形貌的影响。初步研究了锌镍合金镀层组成、结构与镀层的氢脆性、耐蚀性的关系。开发研究了添加剂AS-903,使用添加剂AS-903后,氯化物体系得到的镀层能满足低氢脆和高耐蚀性的性能要求。添加剂AS-903能够改善镀层的氢脆性能,提高电流效率,改变镀层结晶形态,但是随着添加剂含量增加,镀层的脆性增大,因此添加剂的含量应适量。操作温度为38~42℃、电流密度为2~4A/dm2时,含有添加剂AS-903的氯化物体系得到的镀层镍含量质量分数为11%~13%,镀层外观细致均匀,与基体结合力强,并且钝化后耐蚀性能良好,氢脆性能符合航空行业工业(HB5607)标准。用缺口持久拉伸拉伸实验和氢含量测试实验共同证实了镀层及基体的氢脆性能。考察了镀后热处理温度、基体材料、电镀前处理弱腐蚀时间对氢脆的影响。研究表明,300M、35CrMnSiA抗氢脆性能优于65Mn。氢含量测试结果表明,碱性镀锌氢含量最高,氯化钾镀锌次之,电镀锌镍合金氢含量最低。镍含量为13%左右的锌镍合金镀层主要由的γ相的金属间化合物Ni5Zn21组成,热稳定性及耐蚀性较好。镍的存在有利于抑制Zn(OH)2向ZnO转化,同时,镀层的组织结构呈现网状微裂纹,这些都增加了镀层的耐腐蚀性能。镀层氢脆机理倾向于氢与位错交互作用。锌镍合金共沉积机理倾向于氢氧化物抑制机理,即异常共沉积。更多还原

【Abstract】 Zinc-Nickel alloys are a kind of new and protective coatings and have been developed for recent twenty years. This alloy has a promising future because of their high corrosionresistance, low hydrogenous brittleness, facile jointing and good mechanical properties. This paper describes a fundamental study of the hydrogen uptake resulting from electroplating with zinc-nickel alloys in chloride electrolyte.The influence of various of parameters, for example, the solution temperature, PH and cathode current density on the nickel content in theelectrodeposited zinc-nickel alloys coating have been investigated.The additive AS-903 which makes the alloys coatings to have low hydrogen embrittlement and high crrosion resistance has been investigated. This additive can improve the hydrogen embrittlement and current efficiency. If too much additive is used, the coating is brickle. And the satisfactory alloy deposit with Nichle content about 11%~13% can be obtained at 38~42℃and cathode current density 2~4A/dm2 from the chloride-acetic bath. It has good corrosion resistence after passivation and the surface is uniformity and bright, according to the Chinese standard of avigation and spaceflight (HB5607).The results of evaluated of hydrogen uptake test and hydrogen content test show that Zinc-nickel alloys coating present a low hydrogen embrittling. The effects of heat treatment temperature and material and pre-dispose are investigated. It can be concluded that the hydrogen embrittlement of 300M and 35CrMnSiA are superior to 65Mn. The result of hydrogen content test shows that galvanization has the highest hydrogen content test and Zn-Ni alloys coating exhibit low hydrogen embrittlement.The predominant phase found in the Zn-Ni alloy with 13%Ni deposit was gamma-Ni5Zn21 phase which has good hot stability and corrosion resistence. The presence of Nickle will restrain the change from Zn(OH)2 to ZnO. The reticulation of Zn-Ni alloy coating adds the corrosion resistence. The electrodeposition of a metallic coating on the high strength steel introduces the possibility that the steel fail by hydrogen embrittlement. In the deposition of Zn- Ni alloy, the predominant presence of Zinc is result of anomalous codeposition.更多还原