纳米TiO_2对硼酸镁晶须增强镁基复合材料表面Ni-P化学镀层形貌及耐蚀性能的影响

Effect of Titanium Dioxide on Morphology and Corrosion Resistance of Electroless Ni- P Coating on AZ91D Magnesium Matrix Composite Reinforced by Mg_2B_2O_5 Whisker

目前,对镁基复合材料表面能否得到耐蚀性优良的Ni-P-Ti O2复合镀层研究不多。为了提高镁基复合材料的耐蚀性,在硼酸镁晶须增强AZ91D镁基复合材料表面制备了Ni-P化学镀层和Ni-P-纳米Ti O2复合化学镀层。采用扫描电镜(SEM)观察镀层表面形貌,用电化学方法研究了镀层的电化学性能,并分析了添加纳米Ti O2对镀层耐蚀性的影响。结果表明:施镀2 h后,Ni-P-Ti O2镀层厚度约为12μm;与Ni-P镀层相比,纳米Ti O2颗粒的加入细化了镀层晶粒,同时造成了镀层疏松,镀液中Ti O2浓度为2 g/L时得到的复合镀层的自腐蚀电位为-0.8 V,耐蚀性降低,但仍对基体有保护作用。

Electroless Ni-P and Ni-P-TiO_2 composite coating were prepared on AZ91 D magnesium matrix composite reinforced by Mg_2B_2O_5 whisker so as to improve the corrosion resistance.The surface morphology of the coatings was observed with a scanning electron microscope,and the electrochemical properties of the coatings were investigated by electrochemical method.Moreover,the impact of Til),on the corrosion resistance of Ni-P coating was examined.Results showed that,after 2 h of electroless plating,Ni-P-TiO_2 coating had a thickness of about 12μm.As compared with electroless Ni-P coating,the introduction of TiO_2nanoparticles caused refining of the grains as well as loosening of the coating.When 2 g/L of TiO_2 was added into the electroless Ni-P bath,resultant Ni-P-TiO_2 composite coating exhibited a corrosion potential of-0.8V,and the corrosion resistance of the composite coating was slightly reduced,but it was still able to protect the Mg matrix composite.