碳钢管内表面化学镀Ni-P耐蚀层的研究

为了在Q235钢管内表面制备Ni-P化学镀层,以提高普通碳钢管道的耐蚀性,通过正交试验研究化学镀的镀液配方,并检测镀层的化学成分及其在盐水中的耐蚀性。研究表明:Q235钢管内表面制得的Ni-P化学镀层最佳配方为硫酸镍7.6×10^-2mol/L,次亚磷酸钠0.17 mol/L,柠檬酸钠3.4×10^-2mol/L,硫脲1.32×10^-5mol/L;镀层沉积速率为25.4μm/h,镀层硬度为747 HV;镀层中Fe、Ni和P元素的质量百分比分别为0.89%、85.63%和13.48%;在3.5%的NaCl溶液中镀层的自腐蚀电位为-0.62 V(SCE),自腐蚀电流密度为5.82×10^-6A/cm^2,比Q235钢的自腐蚀电流密度降低了98.1%。

Study on Electroless-plated Ni-P Anti-corrosion Coating on Internal Surface of Carbon Steel Pipe

In order to prepare Ni-P electroless-plated coating on the internal surface of the Q235 steel pipe for the purpose of improving the corrosion resistance of ordinary carbon steel pipes,the formula of the electroless plating solution is obtained by the orthogonal testing method.And the chemical composition and corrosion resistance in salt water of the obtained electroless-plated coating are also tested.The study result reveals that the optimal formula of the said Ni-P eleetroless-plated coating consists 7.6×10^-2 mol/L nickel sulfate,0.17 mol/L sodium hypophosphite,3.4×10^-2 mol/L sodium citrate and 1.32×10^-5 mol/L thiourea.Its plating rate is 25.4 μm/h,and the coating hardness is 747 HV.The mass ratios of the three elements(P,Ni anti Fe)in the coating are respectively 13.48 wt.%,85.63 wt.%and 0.89 wt.%.The selfcorrosion potential of the coating in the 3.5 wt.%NaCI solution is -0.62 V(SCE),while its self-corrosion current density is 5.82×10^-6 A/cm^2,being about 98.1%reduction than that of the neat Q235 steel.