【作者】 卢光波；

【导师】 李宁；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2011， 硕士

【摘要】 液压支柱是矿井下常用的机械支撑装置,为提高液压支柱的抗腐蚀性能,常在支柱表面进行化学镀镍处理。但在实际的生产中,由于前处理不充分（或者过度）、化学镀过程中操作不当等原因,常常会导致化学镀镍磷合金层产生比较高的孔隙率,导致形成以铁基体为阳极,化学镀镍层为阴极的腐蚀微电池,加剧腐蚀。因此,有必要研究化学镀Ni-P合金镀层孔隙率的影响因素以及降低对策。本文首先使用扫描电镜（SEM）测试验证了贴滤纸法无法定量、准确表征化学镀镍磷合金镀层微孔,首次提出了用铁溶出值定量表征化学镀镍磷合金镀层孔隙率的方法。确定了铁溶出值法测试溶液的组成:腐蚀介质H₂SO₄、氧化剂为H₂O₂、显色剂为KSCN。设计了一个简易的铁溶出实验槽,并确定了测试的操作规范,测得了铁离子吸光度标准曲线,并推导出了铁溶出值与透射率之间的计算公式,并用定量的方法证明了镍（镍离子）对铁离子吸光度没有影响。对铁溶出值法和贴滤纸法进行了对照,验证了铁溶出值法的可靠性。研究了基体及前处理对镀层孔隙率的影响,发现在不同材质基体上相同厚度的镀层,孔隙率不一致;表面粗糙度越低,孔隙率越低。前处理对孔隙率影响很大,不除油和不酸洗将会导致极高的孔隙率。研究了化学镀镍过程对镀层孔隙率的影响,发现随着化学镀周期的增加即镀液的老化,孔隙率升高。使用400r/min磁力搅拌、强超声波、热启镀、间歇提拉、及时补加等操作方式有利于降低孔隙率。分别选取十二烷基硫酸钠（SDS）、十六烷基三甲基溴化铵（CTAB）、OP-10三种具有代表性的阴离子、阳离子、两性表面活性剂进行研究,得到各自在化学镀镍浴中的最佳浓度分别为20ppm、1ppm、20ppm,都能明显降低孔隙率。另外比较了三种表面活性剂在最佳使用浓度时的封孔效果,发现OP-10最好、十二烷基硫酸钠次之,十六烷基三甲基溴化铵最差,但区别很小。研究钝化处理对孔隙率的影响,发现用30g/L的K₂Cr₂O₇钝化10min（70℃）可以降低化学镀镍磷合金镀层的孔隙率。进行Tafel和EIS测试,发现经钝化后的化学镀镍磷合金镀层与未钝化的相比,耐蚀性明显提高,跟孔隙率明显降低相一致。此外,与单次钝化相比,进行多次钝化和空停更能降低孔隙率。更多还原

【Abstract】 Hydraulic pillars are commonly used for mechanical support equipment under mine, to improve the corrosion resistance of hydraulic props, electroless nickel plating surface treatment are often used on the surface of pillars. However, in actual production, because of pre-treatment not fully（or over）, improper operation in process of electroless plating or other reasons, it often results in relatively high porosity on the surface of electroless nickel-phosphorus alloy, and then leads to formation of corrosion micro-batteries with iron substrate as its anode and nickel plating as its cathode, results in corrosion accelerated. Therefore, it is of great significance to research the factors which affects the porosity of electroless nickel-phosphorus alloy and reduction measures.First of all, scanning electron microscopy （SEM） test was used to prove that the microporous of electroless nickel-phosphorus alloy coating could not be accurately and quantitatively characterize in the way of posting filter, iron solubility value was first used to quantitatively characterize the porosity of electroless nickel plating in this paper. The composition of the iron solubility test solution was determined, a simple iron solubility experimental tank was designed, and the test practices were determined, iron absorbance standard curve was tested, and the formula between transmission rate and iron solubility value was derived, quantitative method was used to prove that nickel（Ni ion） did not affect the absorbance of iron ions. The iron solubility value method was compared with the posting filter method and was proved to be reliable.Impacts of matrix and pre-treatment on porosity of coating were researched, the same thick coatings on different matrix of materials, different porosity; the lower surface roughness was, the lower porosity was. Pre-treatment had a great influence on the porosity, no degreasing and acid washed wiould lead to very high porosity. The effect of process of chemical plating on the porosity were researched, with the increase of plating cycle or the aging of the bath, the porosity increased. 400r/min magnetic stirring, strong ultrasound, hot start-plated, intermittent lifting and immersed in the bath and timely additional helped to reduce porosity.Three representative anionic, cationic, amphoteric surfactants, sodium lauryl sulfate（SDS）, OP-10 cetyltrimethylammonium bromide（CTAB）, were selected to be studied, the conclusion was that their respective best concentration in electroless nickel plating bath ware 20ppm, 1ppm and 20ppm, they could significantly reduce the porosity. Also sealing effect of three surfactants were compared when they were in their respective best concentration in electroless nickel plating baths, and found that OP-10 was best, followed by sodium dodecyl sulfate, cetyltrimethylammonium bromide worst, but the difference was little.The impacts of passivation treatment to the porosity were researched, it was found that it could reduce porosity of Ni-P alloy coating after passivated in 30g/L K₂Cr₂O₇ for 10min at 70℃. Tafel and EIS tests were used to found that compared to unpassivated, the corrosion resistance decreased significantly for by-passivated Ni-P alloy coating, consistent with the porosity significantly reduction. In addition, compared with a single passivation, several passive and air parked reduced the porosity.更多还原