碱性镀液电沉积纳米晶Ni-Mo合金层的制备及其结构

Preparation and structure of nanocrystalline Ni-Mo alloy coating by electrodeposition in alkaline solution

在碱式碳酸镍溶液中获得了纳米晶结构Ni-Mo合金,利用扫描电子显微镜(SEM)、X射线衍射(XRD)等技术对镀层结构进行分析,结果表明,镀层由Ni Mo和β-Ni4Mo两相组成,晶粒尺寸约为23.2nm。Ni Mo合金固溶体呈(111)晶面择优取向;β-Ni4Mo固溶体表现为较强的(200)晶面择优取向。电沉积参数对镀层外观、表面形貌和结合力有较大影响,当镀液pH值10.0左右,温度为30～35℃,电流密度为2～5A/dm2时,可以获得镀层外观质量和结合力良好的Ni-Mo合金镀层。镀液钼酸盐浓度增大,镀层中含钼量增加,镀层硬度先增加后下降,在钼酸盐浓度为8～12g/L时硬度最高,镀层强化主要为固溶强化所致。镀液中钼酸盐和氨水浓度影响镀层内应力。

The nanocrystalline Ni-Mo coating was obtained in the basic nickel carbonate solution. The coating surface and structure were analyzed by using scanning electron microscopy （SEM）, X-ray diffraction （XRD）. The results show that the coating is composed of two phases of NiMo and β-Ni4 Mo, and its grain size is about 23.2nm. NiMo and β-Ni4 Mo solid solution exhibits preferred orientation （111 ） and （200） , respectively. The eleetrodepositing parameters have great influence on surface morphology and binding strength of the coatings. The better electrodeposited Ni-Mo alloy coating is obtained when the solution pH value is around 10.0, the temperature is 30 - 35℃ , and the current density is 2 -5A/dm62 . With increasing the molybdenate concentration in the bath, Mo content of the coating increases and hardness of the coating first increases to a peak value at about 8 - 12g/L, and then decreases. The increase of coating hardness is due to the solid solution strengthening. Molybdate and ammonia concentration in the bath influence the internal stress of the coating.