表面技术
錶麵技術
표면기술
SURFACE TECHNOLOGY
2015年
2期
24-28,47
,共6页
镁合金%化学镀%前处理%稳定性
鎂閤金%化學鍍%前處理%穩定性
미합금%화학도%전처리%은정성
magnesium alloy%electroless plating%pretreatment%stability
目的:开发一种无铬、低氟、稳定的镁合金直接化学镀镍工艺。方法通过SEM,EDX及浸泡实验、动电位极化曲线、划格试验等方法,以稳定系数和镀速等参数为对象,对比新工艺和传统工艺对镀层或镀液性能的影响。结果在以硫酸镍为主盐的基础液中,添加质量浓度为0.5 mg/L的硫脲,镀液的稳定性可得到明显的提高。在使用硝酸+磷酸酸洗后的镁合金试样表面,获得了良好的腐蚀形貌结构,这种结构有利于增强镀层与基底间的机械咬合作用。新工艺获得的镀层属高 P 镀层(P 的质量分数约为11%),在NaCl溶液中的自腐蚀电位由-1.5 V正移至-0.5 V,腐蚀电流密度降低了约3个数量级。结论以硫酸镍主盐镀液获得的镀层耐蚀性优于碱式碳酸镍主盐镀液获得的镀层,镀液的最佳pH=5,化学镀镍温度为82益。
目的:開髮一種無鉻、低氟、穩定的鎂閤金直接化學鍍鎳工藝。方法通過SEM,EDX及浸泡實驗、動電位極化麯線、劃格試驗等方法,以穩定繫數和鍍速等參數為對象,對比新工藝和傳統工藝對鍍層或鍍液性能的影響。結果在以硫痠鎳為主鹽的基礎液中,添加質量濃度為0.5 mg/L的硫脲,鍍液的穩定性可得到明顯的提高。在使用硝痠+燐痠痠洗後的鎂閤金試樣錶麵,穫得瞭良好的腐蝕形貌結構,這種結構有利于增彊鍍層與基底間的機械咬閤作用。新工藝穫得的鍍層屬高 P 鍍層(P 的質量分數約為11%),在NaCl溶液中的自腐蝕電位由-1.5 V正移至-0.5 V,腐蝕電流密度降低瞭約3箇數量級。結論以硫痠鎳主鹽鍍液穫得的鍍層耐蝕性優于堿式碳痠鎳主鹽鍍液穫得的鍍層,鍍液的最佳pH=5,化學鍍鎳溫度為82益。
목적:개발일충무락、저불、은정적미합금직접화학도얼공예。방법통과SEM,EDX급침포실험、동전위겁화곡선、화격시험등방법,이은정계수화도속등삼수위대상,대비신공예화전통공예대도층혹도액성능적영향。결과재이류산얼위주염적기출액중,첨가질량농도위0.5 mg/L적류뇨,도액적은정성가득도명현적제고。재사용초산+린산산세후적미합금시양표면,획득료량호적부식형모결구,저충결구유리우증강도층여기저간적궤계교합작용。신공예획득적도층속고 P 도층(P 적질량분수약위11%),재NaCl용액중적자부식전위유-1.5 V정이지-0.5 V,부식전류밀도강저료약3개수량급。결론이류산얼주염도액획득적도층내식성우우감식탄산얼주염도액획득적도층,도액적최가pH=5,화학도얼온도위82익。
Objective To develop a chromium-free and stable direct electroless nickel plating ( ENP) technology for magnesium alloy. Methods SEM, EDX, immersion test, polarization curves, scribe and grid test as well as the stability factor and deposition rate were used to compare the effects of the new and traditional processes on the characteristics of the performance of Ni-P coating and plating bath. Results The stability of the base solution with nickel sulfate as the main salt could be obviously improved when 0. 5 mg/L of thiourea was added. A good corrosion morphology structure of the AZ91D magnesium alloy was achieved after pickling in a mixture of nitric acid and phosphoric acid. This specific surface structure could improve the mechanical adhesion between the substrate and the coating. The coating prepared using the new technology belonged to high-P coating, with a P content of about 11%. Compared to the bare magnesium alloy, the potentiodynamic polarization test in NaCl solution showed that the corrosion po-tential and the corrosion current density of the new coating increased positively from -1. 5 V to -0. 5 V and decreased by three or-ders of magnitude, respectively. Conclusion The corrosion resistance of coating obtained from a plating bath using nickel sulfate as the main salt was better than that from a plating bath using basic nickel carbonate as the main salt. The optimal pH and temperature of the ENP processes were 5 and 82 ℃, respectively.