摘要
在传统瓦特化学镀镍磷基础上,采用稀土改良型化学镀镍磷配方,在A3钢基体表面制备Ni-P/n-CeO2化学复合镀层。研究添加纳米稀土CeO2对酸性Ni-P化学镀层的制备及耐蚀性能的影响。研究结果表明,稀土纳米颗粒CeO2合理加入量在15～20g/L,稀土纳米颗粒吸附在基体表面,降低界面能,形成自发形核的催化核心,形成纳米晶并细化晶粒,镀层P含量得到有效地提高(12%以上)。复合相颗粒n-CeO2伴随Ni、P复合共沉积,优先填充在微裂纹等缺陷处,降低镀层中杂质元素活性,净化晶界。腐蚀形貌E-SEM观察发现,添加稀土后,镀层由局部点蚀变成均匀化腐蚀,腐蚀程度降低。Tafel曲线测定表明,添加稀土后,复合镀层腐蚀电位正移,电流密度降低。在450℃2h时效热处理过程中,Ni-P/CeO2复合镀层中产生Ni纳米晶化和Ni3P相沉淀析出,并伴随产生化合物NiCe2O4、纳米相CeO2等,生成致密氧化物,钉扎在微孔等缺陷处,降低孔隙率,起到弥散强化作用,对微裂纹扩展起到有效地抑制,提高镀层的致密度和耐蚀性,显微硬度可高达1000HV。
Electroless Ni-P/n-CeO2 composite coatings were preparated under the traditional watt acidic plating solution condition,and its anti-corrosion properties were studied and compared.Ni-P/CeO2 composite coatings were co-deposited on A3 steel substrate surface.The results show that the optimal quantity of CeO2 additive should retain 15-20g/L.Rare earth particles absorb on matrix surface and produce lots of nano-scale nucleus of crystal,refined grain.Only this,nano-CeO2 particle can get dispersed sufficiently and effectively.Rare-earth CeO2 increase the P content（m（P）≥12%）.Rare earth particles n-CeO2 produced at micropore and other defects,decrease activity of impurities,refine the crystal boundary,which due to rare-earth CeO2 nano-particle addictive co-deposite with Ni,P.Corrosion test manifests that rare earth additive CeO2 makes porosity lower,the corrosion morphology of coatings has change from corrosive pitting to be general corrosion,the anti-corrosion property and passivity improve in Ni-P/CeO2 coatings.Electric polarization curves are determined by constant potential rectifier has used to study anti-corrosion resistance,the results show that potential ennoblement and corrosion current drop 1 order of magnitude.The polarization curves slightly move to positive direction and decrease corrosion current density.According to the electrochemistry theory,the corrosion property is improved.Besides,the paper also studys the effect upon heating about microstructure,anti-corrosion resistance and so on.It finds that Ni3P precipitation and Ni crystallization take place at 450℃ 2h heat treatment.In addition,Ni-P/CeO2 coatings have sintered phase of NiCe2O4 spinels,precipitated phase CeO2 is priority produced at micropore and other defects.So,Ni-P/CeO2 composite coatings can get diffused sufficiently and effectively,increase grain density,microhardness can reach 1000HV.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2011年第2期305-309,共5页
Journal of Functional Materials
基金
德国洪堡基金
江苏省自然科学基金资助项目(BK2009374)
