稀土对Ni-P合金梯度镀层工艺及耐蚀性能的影响

论文题目：稀土对Ni-P合金梯度镀层工艺及耐蚀性能的影响专业：材料加工工程硕士生：侯嵬玮(签名)指导教师：孙万昌(签名)摘要稀土元素由于良好的物理、化学、电、磁和光学性能，已经成功地应用在电镀、热镀锌、转化膜及化学热处理等表面处理方法中。非晶态合金镀层由于其结构的特殊性，使其具备了很好的综合物理和化学性能，从而引起了人们的高度重视。梯度功能材料(FGM)是应现代工业的高功能要求而发展起来的全新型未来材料之一，其内部成分和结构的相容性可有效地提高镀层与基体间的结合强度，改善耐蚀耐磨性。本文以LY12硬铝合金为基体，采用化学镀的方法，选取不同的稀土元素作为添加剂，制备了Ni-P非晶态合金镀层。采用扫描电镜(SEM)、能谱(EDS)、X射线衍射(XRD)、显微硬度、腐蚀试验等检测手段，分析了稀土元素及稀土含量对非晶态合金镀层成分、微观结构、硬度及耐蚀性能的影响。实验结果表明：稀土的添加可以提高镀层中P的含量以及镀层的非晶化程度，实现了提高镀层硬度和耐蚀性能的目的。其中添加0.15g/L稀土Y(NO3)3获得的镀层综合性能最好，镀层中P的含量达到12.76%，显微硬度高达641HV，镀层在中性、酸性和碱性环境下均表现出良好的耐蚀性。其次，在Ni-P非晶态合金镀层的基础上，利用功能梯度材料的设计思路，通过改变合金镀层中P元素的含量，实现涂层内部结构逐渐由晶态、晶态+非晶态向非晶态的梯度变化，获得Ni-P合金梯度镀层。试验结果表明：Ni-P梯度镀层与铝合金基体结合良好，且在中性、酸性和碱性环境中，耐蚀能力均优于Ni-P非晶态合金镀层。关键词：LY12铝合金；稀土；Ni-P非晶态合金镀层；Ni-P合金梯度镀层；显微硬度；耐蚀性；浸泡法；极化曲线研究类型：基础应用研究Subject:EfectofRareearthontheProcessandCorrosionresistanceofNi-PalloygradientcoatingsSpecialty:MaterialsscienceandEngineeringName:WeiweiHou(Signature)Instructor:Wan-changSun(Signature)ABSTRACTTherareearthelementhassuccessfullybeenappliedinsurfacetreatingtechniquessuchaselectroplating,hotgalvanization,conversionfilmandheat-treatment.Amorphousalloycoatinghasattractedgreatinterestowingtoitsfavorablephysicalandchemicalproperties.Asoneofthepromisingmaterials,functionallygradedmaterials(FGM)havebeendevelopedunderthehighrequirementofmodernindustry.Inaddition,theadhesivestrengthbetweencoatingandsubstrateaswellasthecorrosionresistanceofthecoatingscanbeimprovedefficientlybyitscomponentandstructurecompatibility.Employingchemicalplatingmethod,amorphousNi-PalloycoatingusingthedifferenttypesofrareearthasadditivesispreparedusingtheLY12alloyassubstrateinthispaper.Theinfluenceofdifferenttypeandcontentofrareearthonthecomposition,microstructure,micro-hardnessandcorrosionresistanceofNi-PamorphousalloycoatingswereanalysedbymeansofSEM,EDS,XRDandortherinstruments.TheresultsshowthatthemicrohardnessandcorrosionresistanceofNi-Pcoatingareimprovedbyaddingtherareearthwhichcanbeabletoincreasethecontentoftotalphosphorusinthecoatingandenhancetheextentofamorphization.ThecomprehensivepropertyofNi-Pcoatingwith0.15g/LY(NO3)3rareearthisthebest.Themicrohardnessis641HVandthecorrosionresistancesofNi-Pcoatinginneutral,acidicandalkalinesolutionsareexcellent.Inaddition,Ni-Palloygradientcoatingwasprepared.TheinternalstructureofNi-PalloygradientcoatingwaschangedfromcrystallinetocrystallineandamorphousandthentoamorphousbymeansofalteringthePcontent.TheresultsshowthatthecohesionbetweenthecoatingandsubstrateandthecorrosionresistancesofNi-PgradientplatingisbetterthanthatoftheamorphousNi-Palloycoatinginneutral,acidicandalkalinesolutions.Keywords:LY12alloy;rareearth(RE);amorphousNi-Palloycoating;Ni-Palloygradientcoating;microhardness;corrosionresistance;immersionmethod;polarizationcurveThesis:BasicApplicationResearch目录I目录1绪论.......................................................................................................................................11.1铝及铝合金的性质.......................................................................................................11.2铝合金的分类...............................................................................................................11.3铝合金的应用...............................................................................................................21.3.1铝材在汽车工业上的应用....................................................................................21.3.2铝合金在航空航天中的应用................................................................................21.3.3铝合金在建筑方面的应用....................................................................................21.3.4铝合金在包装、容器工业上的应用....................................................................31.4铝合金的表面处理技术...............................................................................................31.4.1化学氧化处理........................................................................................................41.4.2阳极氧化处理........................................................................................................41.4.3着色处理................................................................................................................41.4.4封孔处理................................................................................................................51.4.5搪瓷处理................................................................................................................51.4.6电镀处理................................................................................................................61.5铝及铝合金表面化学镀镍...........................................................................................61.5.1化学镀镍的概述....................................................................................................61.5.2化学镀镍的机理....................................................................................................71.5.3非晶态化学镀镍....................................................................................................71.5.4铝合金表面化学镀镍的应用................................................................................8