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研究了在基础镀液中添加镧系稀土化合物改善化学镀Ni-Zn-P的工艺和产品性能。首先采用单因素实验方法考察了基础镀液组成和工艺条件对Ni-Zn-P镀层的沉积速率和耐蚀时间的影响,确定了所有试剂的最佳组成浓度分别为:六水合硫酸镍27 g·L~(-1)、次亚磷酸钠16 g·L~(-1)、柠檬酸钠二水合物90 g·L~(-1)、七水合硫酸锌8 g·L~(-1)、氯化铵46 g·L~(-1),硫酸镉2×10~(-3)g·L~(-1),最佳操作条件分别为pH 9.0和温度90℃。然后重点考察了基础镀液中添加不同浓度的镧系稀土化合物氧化镧、硫酸高铈和氧化镱对镀层的沉积速率、外观形貌、耐腐蚀能力和晶相结构等性能的影响。结果表明,上述性能均随着三种稀土化合物浓度的增加呈先改善而后减弱的趋势,最适宜的浓度分别确定为10×10~(-3)g·L~(-1)、15×10~(-3)g·L~(-1)和15×10~(-3)g·L~(-1)。与基础镀液比较,在添加最适宜浓度的上述三种稀土化合物的情况下,可分别使沉积速率从3.7×10~(-3)g·cm~(-2)·h~(-1)提高至4.3×10~(-3)g·cm~(-2)·h~(-1)、4.4×10~(-3)g·cm~(-2)·h~(-1)和4.5×10~(-3)g·cm~(-2)·h~(-1),耐蚀时间从240 h延长至300 h、275 h和280 h,外观形貌由粗糙、暗淡、不均匀、有局部缺陷变为较平整、光亮、均匀和致密,并使镀层的非晶相程度得到改善,提高了产品的耐蚀性能。
The process and product properties of electroless Ni-Zn-P electroless plating were studied by adding lanthanide rare earth compounds into the base bath. First of all, the influence of basic bath composition and process conditions on the deposition rate and corrosion resistance of Ni-Zn-P coating was investigated by single factor experiment. The optimum concentration of all reagents was determined as follows: 27 g nickel sulfate hexahydrate · L -1, sodium hypophosphite 16 g · L -1, sodium citrate dihydrate 90 g · L -1, zinc sulfate heptahydrate 8 g · L -1 ), Ammonium chloride 46 g · L -1 and cadmium sulfate 2 × 10 -3 g · L -1. The best operating conditions were pH 9.0 and temperature 90 ℃. Then, the effects of lanthanum oxide, lanthanum oxide, cerium sulfate and ytterbium oxide on the deposition rate, morphology, corrosion resistance and crystal structure of the coating were investigated emphatically. The results showed that the above properties all improved and then decreased with the increase of the concentration of three rare earth compounds. The optimum concentrations were 10 × 10 -3 g · L -1 and 15 × 10 ~ (-3) g · L ~ (-1) and 15 × 10 ~ (-3) g · L ~ (-1) respectively. Compared with the basic bath, the deposition rate increased from 3.7 × 10 -3 g · cm -2 · h -1 with the optimum concentration of the above three rare earth compounds, To 4.3 × 10 -3 g · cm -2 · h -1 and 4.4 × 10 -3 g · cm -2 · h -1 and 4.5 × 10 ~ (-3) g · cm -2 · h -1, the corrosion time was prolonged from 240 h to 300 h, 275 h and 280 h, the appearance of the samples was rough and dull, Uniform, local defects into a more smooth, bright, uniform and dense, and to improve the degree of amorphous coating phase, improve the corrosion resistance of the product.