表面活性剂对Ni-P-Al2O3复合镀层性能的影响

目的 改善Ni-P-纳米Al2O3复合镀层的均匀性,提高其耐蚀性能.方法 采用化学镀法在Q235钢表面制备Ni-P纳米Al2O3复合镀层,分析纳米Al2O3添加量(0～10g/L)对镀层形貌的影响.施镀过程中选用不同种类的表面活性剂来分散纳米Al2O3,通过XRD分析镀层的相组成,采用SEM、EDS研究镀层形貌和成分,通过测量施镀前后纳米Al2O3的Zeta电位来研究非均一镀液的稳定性和纳米粒子的分散性能,利用电化学阻抗手段研究镀膜样品在3.5％NaCl水溶液中的耐蚀性能,从而分析镀液中表面活性剂的种类和用量对复合镀层的影响.结果 随着镀液中纳米粒子添加量的增加,镀层中Al2O3含量先增加后趋于稳定,同时镀层表面纳米Al2O3团聚现象也随之加剧.添加一定量表面活性剂之后,镀层变得均匀,纳米粒子团聚减少,其中阳离子表面活性剂(十六烷基三甲基溴化铵)在低浓度下就能对纳米Al2O3分散产生显著作用,而阴离子表面活性剂(十二烷基苯磺酸钠)需在较高浓度下才能达到相似效果.结论 当镀液中阴离子表面活性剂用量为1.25cmc,Al2O3添加量为6g/L时,镀层最为均匀,且样品在3.5％NaCl水溶液中耐蚀性能最好.

Effect of Surfactants on the Properties of Electroless Ni-P-Al2O3 Composite Coatings

Objective To improve the uniformity and corrosion resistance of Ni-P-nano Al2O3 composite coatings. Methods Ni-P-nano Al2O3 composite coatings were obtained by adding different amounts of nano Al2O3 powder (concentrations ranging from 0 g/L to 10 g/L) into the traditional Ni-P electroless bath. And the morphology of the coatings was studied. Different concentrations of anionic/cationic surfactants were added into the bath to disperse the nano particles. The microstructure of the samples was studied by X-ray diffraction (XRD). The surface morphology and composition of the samples were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). The bath stability and dispersion of nano particles were determined by change of Zeta potential of Al2O3. Corrosion resistance of all the samples was evaluated in 3.5wt% NaCl solution by electrochemical impedance spectroscopy (EIS). In that way, the effects of different types and amounts of surfactants on the properties of composite coating were studied. Results With the increasing amounts of Al2O3 in the bath, the content of Al2O3 in coating increased firstly and then became stable. Yet Al2O3 agglomerated on the surface of coatings. Surfactants would affect the dispersion of nano particles, creating a coating with less agglomerated Al2O3 on the surface. A lower amount of cationic surfactant (CTAB) would disperse the nano particles very well while a higher concentration of anionic surfactant (SDBS) was required toget similar effect. Conclusion The coating formed in the bath with 6g/L nano Al2O3 and 1.25cmc SDBS exhibited the best homogeneous morphology and corrosion resistance in 3.5% NaCl solution.