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采用增重法、精密pH计、扫描电镜(SEM)和动电位极化曲线测定和分析了镀液的镀速、镀液的缓冲性、镀层的表面形貌和镀层的耐蚀性,研究了不同浓度NH_4HF_2对AZ31镁合金化学镀镍层性能的影响.结果表明,NH_4HF_2的浓度影响镀液的镀速及缓冲性、镀层的形貌及耐蚀性.当NH_4HF_2的质量浓度为5～15 g/L时,镀速随浓度的增加递增,而当NH_4HF_2的质量浓度为15～25 g/L时,镀速随浓度的增加而减少;镀液缓冲性随NH_4HF_2浓度的增加而提高.当NH_4HF_2的质量浓度为15 g/L时,镀速达到最大值21.9μm/h;当NH_4HF_2的质量浓度为20 g/L时,镀层致密完整且阳极极化曲线的钝化电位区间最大,自腐蚀电流密度最小,因此,此时镀层的耐蚀性最好.
The plating speed, the buffer solution of the bath, the surface morphology of the coating and the corrosion resistance of the coating were measured and analyzed by using the weight gain method, the precision pH meter, the scanning electron microscope (SEM) and the potentiodynamic polarization curve. The results showed that the concentration of NH_4HF_2 affected the plating speed and buffer properties, morphology and corrosion resistance of the coating.When the concentration of NH_4HF_2 was 5 ~ 15 g / L, the plating rate increases with the increase of NH4HF2 concentration, while when the mass concentration of NH4HF2 is 15 ~ 25 g / L, the plating rate decreases with the increase of concentration; When the mass concentration of NH4HF2 is 20 g / L, the coating is dense and the passivation potential range of the anodic polarization curve is the maximum, and the corrosion rate of self-corrosion current The minimum density, therefore, the corrosion resistance of the coating at this time the best.