纳米硬度计测定电刷镀纳米颗粒复合镀层的弹性模量

采用电刷镀技术在钢基体表面制备了n-Al2O3／Ni纳米颗粒复合镀层，借助纳米硬度计的纳米压痕法测定了复合镀层的弹性模量及其分布。测试结果表明：n—Al2O3／Ni纳米颗粒复合刷镀层的杨氏模量约为200GPa；复合刷镀层中存在的气孔、裂纹等缺陷处具有较低的弹性模量，除这些缺陷微区外，复合刷镀层具有均一的弹性模量等力学性能。指出优化和严格控制复合刷镀层制备工艺、减少或消除镀层缺陷，是纳米颗粒复合刷镀层具有均匀性能、提高宏观力学性能的有效途径。     

n-Al2O3/Ni-P复合电刷镀层的组织及摩擦磨损特性

研究了镍磷基纳米Al2O3复合电刷镀层(n—Al2O3／Ni-P)的组织特征及摩擦磨损特性，并与镍磷合金刷镀层进行了比较。结果表明：n—Al2O3／Ni—P复合刷镀层表面粗糙度更小，组织有明显的细化倾向；当镀液中n—Al2O3含量为20g／L时，复合刷镀层的硬度最高，达561HV，是Ni-P镀层硬度的1．3倍，此时复合镀层的耐磨性也最好，磨损失重相比于Ni—P镀层，减少60％以上。     

n-Al2O3/Ni复合镀层的组织与接触疲劳行为

利用SEM和TEM分析了n-Al2O3／Ni复合镀层的表面形貌和微观组织,研究了该镀层的接触疲劳行为。结果表明,复合刷镀层的表面形貌细腻,镀液中纳米Al2O3颗粒含量较低时这些颗粒在镀层中呈弥散分布,而含量较高时存在一定的团聚。随着镀液中纳米Al2O3颗粒含量的增加,复合镀层的接触疲劳寿命逐渐增加,含量为20g/L时达到最大,约为190万次,是纯镍镀层的1．5倍;含量进一步增加时,寿命急剧降低。失效分析表明,纯镍镀层的疲劳断口发生强烈的塑性变形;镀液中纳米Al2O3颗粒含量为40g/L时,复合镀层的疲劳断口呈现脆性断裂特征。     

纳米Al2O3颗粒含量对复合镀层组织和滑动磨损行为的影响

采用电刷镀技术在45钢表面制备了纳米Al2O3颗粒增强镍基复合镀层，研究了纳米Al2O3颗粒在镀液中的含量对镀层的组织、力学性能和摩擦学性能的影响，并分析探讨了影响机理。结果表明，随着镀液中纳米Al2O3颗粒含量的增加，复合镀层的组织趋于细化，在含量为20g／L时复合镀层的硬度和耐磨性出现极值，其磨损机制也随之发生改变，这与纳米Al2O3颗粒在复合镀层中的含量和分布状态密切相关。     

纳米Al2O3p/Ni复合刷镀层的组织与性能研究

制备了纳米A2O3p／Ni的复合刷镀层，测试了复合刷镀层的硬度、耐磨性、抗接触疲劳性能及高温性能，并分析了复合刷镀层的金相组织。结果表明：纳米颗粒复合刷镀层的硬度是不含纳米颗粒的快速镍刷镀层的1．7倍，耐磨性是其2．5倍，抗疲劳寿命提高到10^6周次，可服役温度提高到450C；纳米颗粒复合刷镀层的强化机制主要为细晶强化，弥散强化和位错强化。     

耐磨Ni-Al2O3复合镀层组成机理及性能研究

在纯铜板上制备Ni-Al2O3 纳米复合镀层,并通过SEM观察了Ni-Al2O3复合镀层的表面形貌结构及微粒分布状态,并对镀层进行X-射线衍射分析和利用HXD-1000显微硬度计测量镀层微区硬度.结果表明Ni-Al2O3复合镀层有完全不同于纯镍镀层的组成结构,Al2O3颗粒的加入能够有效的阻碍镍晶粒的长大,且在颗粒附近复合镀层的硬度比纯镍的硬度成倍地提高.Al2O3颗粒越细小这种作用越明显.     

纳米Cr2O3复合电刷镀镀层性能研究

在快速镍镀液的基础上,通过添加纳米Cr2O3粉末得到了纳米复合镀液,制备了纳米Cr2O3颗粒的镍基复合镀层,通过显微硬度、孔隙率、耐腐蚀与极化曲线、SEM等测试手段,比较了纳米复合镀层与纯镍镀层的性能,结果表明：纳米Cr2O3复合刷镀镍层的截面硬度比纯镍镀层的截面硬度提高8.3%,两种镀层与基体结合良好;纳米Cr2O3复合镀层的表面形貌比纯镍镀层更加细化且耐腐蚀性有所提高。     

摩擦喷射纳米Al2O3/Ni复合镀层的组织形貌及其性能研究

采用摩擦喷射电沉积工艺制备了纳米Al2O3／Ni复合镀层，考察了该镀层的表面和断面形貌，并对镀层性能进行了测试分析。研究表明，摩擦喷射纳米Al2O3／Ni复合镀层表面较为平整，镀层与基体结合紧密。一次性镀覆厚度达到1．40mm，远高于电刷镀纳米Al2O3／Ni复合镀层（0．35mm），镀层硬度达到650HV。在试验条件下，该镀层的耐磨性是摩擦喷射Ni镀层的1．44倍，是纳米Al2O3／Ni刷镀层的1．15倍，摩擦因数也低于摩擦喷射Ni镀层和电刷镀纳米Al2O3／Ni复合镀层。     

纳米Al2O3／Ni复合电刷镀层的表征与微动磨损机理

通过在镍基电刷镀液中添加纳米Al2O3颗粒,制备出了分散均匀、与基质金属Ni结合良好的Al2O3／Ni复合电刷镀层。复合镀层的组织致密,显微硬度高。微动磨损试验表明,复合镀层在常温及高温下抵抗微动磨损的能力均强于普通快镍镀层。这是因为,随着纳米颗粒的加入,Al2O3／Ni复合电刷镀层受到细晶强化、位错强化和弥散强化,抵抗塑性变形和粘着破坏的能力增强,从而具有良好的耐微动磨损性能。     

Ni-Al2O3纳米复合镀层的氧化性能研究

采用复合电镀技术,通过向普通电镀溶液中加入平均粒度为90nm的Al2O3粉的方法在Ni基材上制备了Ni-Al2O3纳米复合涂层,SEM/EDAX分析表明,Al2O3纳米颗粒不仅均匀分布在Nj纳米晶中,而且还细化了基体Ni的晶粒尺寸.1000℃氧化实验表明:弥散分布在镀层中的Al2O3,纳米粒子并没有明显提高Ni的氧化性,但通过阻碍氧化过程中Ni的外扩散从而改变了NiO膜的形成过程.     

电刷镀镍基Al2O3复合镀层组织和性能的研究

应用复合电刷镀技术制备了含有Al2O3陶瓷颗粒的镍基复合镀层,对复合镀层表面形貌进行了研究,对镀层的显微硬度和摩擦磨损性能进行了测试,并分析了Al2O3对镀层磨损性能的影响.结果表明,细小的Al2O3陶瓷颗粒复合镀层较快速单一镍镀层具有更高的显微硬度和良好的耐磨性.     

THE EXPERIMENTAL STUDIES OF NiO CLUSTER FORMATION IN Ni_3Al ALLOYS BY AP-FIM

1. IntroductionFOr maily years, the room temperature brittleness of the polyer}l'stalline Ni3AI was recognized to be "intrinsically brittl.5,[1'2] due to brittle grain--boundary fracture. Recentlyit hajs been shown that environmental embrittlement is a major cause of the poor ductiLity of NiaAI in air[3--sl, and the embrittlement mechanism involves chemical .eactio.sfsl=M HzO-MO ZH or M HaO-MOH H. Where M is a reactive element in the intermetallic compound (Ni and Al) which reacts ch…     

EFFECT OF MICROSTRUCTURE CHANGE ON OXIDE FORMATION OF SPUTTERED Ni-3Cr-10Al NANOCRYSTALLINE COATING

1.IntroductionThesputterednanocrystallinecoatingswiththesameconlpositionasthesubstrateweresuccessfullyappliedtoK38G[ll,Kl7F[2]lLDZc5[3]Ni-basetlsuperalloys.Themaincharacterizati0nisthatnan0crystallizati0ncouldimpr0vetheselectiveoxidationofAl,therefore,thetransiti0nfr0minternalt0externaloxidati0nofAlisrealizedandanex-ternalAl2O3scaleisfOrn1ed.Niisthemainingredient0fNi-basedsuperal1oysandtheeffectivenessofthesesuperal1oysdependsgreatly0ntllepresellceofAlorCrtoformaprotectivelayerofAl2O:jo…     

Oxidation Behavior of Ni-3, 6 wt% Al Alloys at 800 °C in Atmospheres Containing Water Vapor

The oxidation behavior of Ni, Ni–3Al, and Ni–6Al alloys at 800 °C in air + H₂O was investigated. The oxidation kinetics of Ni and the alloys in air + H₂O were very similar, but the mass gains of Ni and each alloy were smaller in air + H₂O than in air. Oxidation products formed on Ni-3 and 6Al alloys consisted of an outer NiO scale and internal Al₂O₃ precipitates. The growth rates of both NiO and the internal oxidation zone were much smaller in air + H₂O. The NiO scale formed in air + H₂O was duplex in structure with outer porous and inner dense layers. The outer porous layer consisted of fine powder-like NiO particles. A thicker metallic Ni(Al) layer formed at the NiO/alloy interface in air + H₂O, caused by extrusion of Ni from the substrate due to volume changes accompanying the internal oxide formation. Formation of the metallic Ni layer appeared to be the reason for the similarity between the oxidation kinetics of both Ni and the alloys in air + H₂O.     

TiAl合金表面等离子喷涂MCrAlY涂层热腐蚀行为研究

研究TiAl合金表面等离子喷涂NiCoCrAl-Y2O3涂层在850 ℃下对75%Na2SO4+25%NaCl熔盐的热腐蚀行为,及对TiAl金属间化合物抗高温热腐蚀性能的影响。研究表明,在850 ℃,等离子喷涂NiCoCrAl-Y2O3涂层由于生成Cr2O3,NiO和NiCr2O4等各种氧化物组成的氧化层,显著提高了TiAl基体的抗热腐蚀性能。在热腐蚀过程中,S元素以Ni元素为载体,逐步渗入涂层中,生成过渡产物Ni3S2。随着O分压的升高,反应进入了氧化阶段,生成Cr2O3、NiO等氧化物,随着两种物质含量的增加,最后发生固相反应,生成尖晶石结构的NiCr2O4化合物。过渡产物Ni3S2与腐蚀介质中的Cl-离子形成微电池,可以加快热腐蚀反应速度     

水蒸气对NiCrAlY涂层抗高温氧化性能的影响

采用热重分析及现代表面分析方法研究了低压等离子喷涂Ni CrAlY涂层在纯氧以及含5%水蒸气的O2中的高温氧化行为,结果表明：在纯氧的氧化环境中 ,NiCrAlY涂层氧化动力学遵循抛物线规律,在含有5％的水蒸气的O2中,NiCrAlY涂层在氧 化至110 h后氧化动力学几乎呈直线规律.XRD及SEM分析显示,NiCrAlY涂层在O2中氧化180 h后,表面形成一层致密的Al2O3;而在含5%水蒸气的O2中氧化180 h后表面氧化层中 除了有Al2O3外,还有NiO和Cr2O3.其原因在于水蒸气中的氢在氧化物中的溶解,致 使Ni2+扩散 速度增加,使氧化层变得疏松,降低其抗氧化性.     

EFFECT OF Ce ON OXIDATION BEHAVIOUR OF Ni_3Al ALLOYS

1.IntroductionIntermetallicc0mp0undNi3Alhasthespecificpropertythattheyieldstrengthim-proveswiththeincrease0ftemperature.Thefundamentalresearchonhigh-temperaturestructuralmaterialshaJsmademuchprogress,andther0omtemperaturetensilepr0pertiesofNisAlalloysareimproveddramaticallywiththeaddition0falittleB[1'2].Beingasurfaceactiveelement,Cecanpurifyandmodifysteels,andimprovetheirductility,t0ughness,oxidationresistanceandc0rrosionresistance[3].Theeffect0fCe0nthefabricabilityandroomtemperaturetensil…     

超音速颗粒轰击处理对MCrAlY涂层TGO生长的影响

采用超音速火焰喷涂方法在镍基高温合金(GH99)上制备了MCrAlY涂层,并进行超音速颗粒轰击处理,研究了超音速颗粒轰击工艺对MCrAlY涂层显微结构和热生长氧化物(TGO)的影响.结果表明,通过表面轰击处理,增加了涂层中Al元素的扩散通道;高温氧化过程中MCrAlY涂层表面很快形成连续致密的Al2O3膜,保护了Ni,Cr等元素避免被氧化,从而避免了Ni(Cr,Al)2O4,NiO等大颗粒氧化物的生成;这样减少了涂层中的裂纹产生和扩展的可能性,从而提高涂层抗高温氧化性能.     

On the Influence of Non-Protective CuO on High-Temperature Oxidation of Cu-Rich Cu-Ni Based Alloys

A number of copper-rich Cu-Ni alloys wereoxidized from 750 to 1000^°C at differentoxygen pressures. The oxide scales formed consist of anouter copper oxide layer and an inner porous layer where internal oxide-derived NiO particles aredispersed in a copper oxide matrix. The copper oxide maybe both single-phase CuO and a two-phase(CuO+Cu₂O). At the lower part of thetemperature range, the oxidation kinetics and oxidemorphology depend strongly upon the formation of CuO.The CuO layer is nonprotective and further oxidation ofCu₂O, forming CuO, therefore changes the oxidation from being approximately parabolic tohaving a breakaway-like behavior. The relative thicknessof nonprotective CuO increases with increasing NiO andreflects that the solid-state flux of copper across the Cu₂O decreases due to abarrier effect of the NiO particles and porosity in theoxide and NiO particles in the alloy. The beneficialeffect of Ni in reducing the oxidation rate is lost due to the extensive formation ofnonprotective CuO.     

Formation of Cr<Subscript>2</Subscript>O<Subscript>3</Subscript> Diffusion Barrier Between Cr-Contained Stainless Steel and Cold-Sprayed Ni Coatings at High Temperature

A novel approach to prepare a coating system containing an in situ grown Cr₂O₃ diffusion barrier between a nickel top layer and 310SS was reported. Cold spraying was employed to deposit Ni(O) interlayer and top nickel coating on the Cr-contained stainless steel substrate. Ni(O) feedstock was prepared by mechanical alloying of pure nickel powders in ambient atmosphere, acting as an oxygen provider. The post-spray annealing was adopted to grow in situ Cr₂O₃ layer between the substrate and nickel coating. The results revealed that the diffusible oxygen can be introduced into nickel powders by mechanical alloying. The oxygen content increases to 3.25 wt.% with the increase of the ball milling duration to 8 h, while Ni(O) powders maintain a single phase of Ni. By annealing the sample in Ar atmosphere at 900 °C, a continuous Cr₂O₃ layer of 1-2 μm thick at the interface between 310SS and cold-sprayed Ni coating is formed. The diffusion barrier effect evaluation by thermal exposure at 750 °C shows that the Cr₂O₃ oxide layer effectively suppresses the outward diffusion of Fe and Cr in the substrate effectively.