配位剂和硫酸锌含量对化学镀Ni-Zn-P工艺的影响

Effects of Contents of Complexing Agent and Zinc Sulfate on Ni-Zn-P Electroless Plating Process

为了给后续三元镀层的研究应用奠定基础,采用化学镀技术在Q235基体上获得Ni-Zn-P镀层,主要研究了配位剂和硫酸锌含量对镀速、镀层成分、形貌和物相的影响,确定了配位剂和硫酸锌的最优含量,并对典型镀层截面形貌、硬度及开路电位进行分析。结果表明:随配位剂含量增加镀速先升高后降低,镀层中Ni和Zn含量先增加后减少;在配位剂为40 g/L时镀层中Zn含量可以达到12.64%,镀层表面平整致密。随硫酸锌含量增加,镀速逐渐下降;镀层中Zn含量逐渐增加,而Ni含量减少。不同配位剂和硫酸锌含量下制备的Ni-Zn-P镀层物相均以Ni非晶为主。综合考虑镀速、形貌、锌含量等因素,确定配位剂含量为40 g/L、硫酸锌含量为8 g/L。Ni-Zn-P镀层显微硬度达到356 HV,是基体的2.66倍,是化学镀Ni-P镀层的1.09倍。Ni-Zn-P镀层在3.5%NaCl中的开路电位明显负于Ni-P镀层,接近Q235钢基体,表明Zn的加入可以降低开路电位。

Ni-Zn-P alloy coating was obtained on Q235 substrate by electroless plating method. The influences of the contents of complexing agent and zinc sulfate on plating speed,composition,morphology and phase composition were studied and the optimal contents of complexing agent and zinc sulfate content were determined. The cross section morphology,hardness and open circuit potential of typical Ni-Zn-P plating coating were analyzed. Results showed that the plating rate increased first and then decreased with the increase of the content of the complexing agent,and the content of Ni and Zn in the coating increased first and then decreased. When the content of the complexing agent was 40 g/L,the Zn content in the coating reached 12.64%,and the coating surface was smooth and compact. With the increase of zinc sulfate content,the plating rate decreased gradually,and in the coating Zn content increased while Ni content decreased gradually. The Ni-Zn-P coating prepared under different contents of complexing agents and zinc sulfate was mainly composed of amorphous Ni. Considering the factors such as plating speed,morphology and zinc content,the contents of complexing agent and zinc sulfate were determined to be 40 g/L and 8 g/L,respectively.The microhardness of the obtained Ni-Zn-P coating was 356 HV,2.66 times as high as that of the substrate and 1.09 times as high as that of Ni-P alloy electroless coating. The open circuit potential of Ni-Zn-P coating at 3.5% Na Cl was significantly lower than that of Ni-P coating,close to that of the Q235 steel matrix,indicating that the addition of Zn could reduce the open circuit potential.