简介:NanostructuredandconventionalAl2O3-13wt%TiO2coatingsweremanufacturedbyairplasmaspray.FrictionandwearbehaviorsofcoatingswereinvestigatedatroomandelevatedtemperaturesusinganSRVweartestmachine.Thenanostructuredcoatinghas"tworegions"microstructure,whiletheconventionalcoatinghastypicallayeredmicrostructurewithobviousinterfacesamongsplats.Thecoefficientoffrictiondecreaseswithrisingoftemperaturebecauseoftheformationoftribo-layeratelevatedtemperatures.Thewearresistanceofthenanostructuredcoatingsishigherthanthatoftheconventionalcoating,andthewearthresholdofappliedloadis30Nforconventionalcoatingand40Nfornanostructurecoating.Thewearresistancedifferenceisrelatedtothe"tworegions"microstructureofnanostructurecoating,whichcouldbluntorbranchthecrackspropagation.Inourtestranges,thewearratesrisingaremoresensitivewiththeappliedwearloadrisingthanwiththetemperaturerising.
简介:Inthisarticle,anovelheattreatmentmethod,deformationheat(DH)treatment(extrusion+aging),wasemployedonahypereutecticaluminumsiliconalloy(LM28-0.3wt.%Nd),anditseffectonmicrostructureandmechanicalpropertiesofthisalloywasinvestigated.ItcanbeconcludedthattheeutecticmicrostructuredisappearsaftertheDHtreatment,inthemeantimethemorphologyofα(Al)solidsolutionwastransformedfromfir-treeandcellulartoequiaxed,Siwasrefinedwithgrainsizesofabout1-10μmanddistributeddispersedly,evensomeofthembecameglobularshape,whichcanreducestressaccumulationeffectively.MechanicalpropertiestestindicatedthattheDHtreatmentcouldsignificantlyimprovetheroom-temperaturestrengthandhavelittleeffectonthehigh-temperaturestrengthofLM28-0.3wt.%Ndalloy.Thefracturemechanismisductilefracturebyfracturemorphologyanalysis.
简介:TheslidingfrictionandwearbehaviorsofMg–11Y–5Gd–2Zn–0.5Zr(wt%)alloywereinvestigatedunderoillubricantconditionbypin-on-diskconfigurationwithaconstantslidingdistanceof1,000minthetemperaturerangeof25–200°C.Resultsindicatethatthevolumetricwearratesandaveragefrictioncoefficientsdecreasewiththeincreaseofslidingspeeds,andincreasewiththeincreaseoftesttemperaturebelow150°C.ThehardandthermallystableMg12(Y,Gd)Znphasewithlong-periodstackingorderstructureinthealloypresentssignificantwearresistance.Thewearmechanismbelow100°Cisabrasivewearasaresultofplasticextrusiondeformation.Thecorporateeffectsofsevereabrasive,oxidative,anddelaminatingwearresultinthetribologicalmechanismabove100°C.
简介:树突的微观结构规模例如主要、第二等的树突手臂间距,在interdendritic区域以内控制分离侧面和第二等的阶段的形成,它决定团结的结构的性质。主要阶段的主要、第二等的树突手臂间距上的调查在这研究在方向性地团结的Pb-26wt%Bi低亚硫酸钠包晶体的合金期间被执行,并且系统的研究与不同直径用圆柱的样品被进行(=1.8和7.0公里)武装间距以便在主要、第二等的树突上分析样品直径的效果。在这个工作,生长速度上的树突手臂间距的依赖被建立。另外,有关主要、第二等的树突手臂间距的试验性的数据与从文学的主要预兆的树枝状的模型相比。在1.8-mm-diameter样品和7.0-mm-diameter样品的树突手臂间距的试验性的结果之间的比较也被进行。
简介:MgTixNi(x=0,0.1,and0.2)alloysweresuccessfullypreparedbymechanicalalloying(MA),andtheinfluenceofmillingtimeontheelectrochemicalcharacteristicsoftheelectrodeswasdiscussed.MgTixNialloysafter90hmillingdisplayedthebestelectrochemicalperformance.TheX-raydiffractionpatternsshowedthatthealloyball-milledfor90hwasamorphouswithawideneddiffractionpeak.Thecharge-dischargetestsindicatedthatthesealloyshadgoodelectrochemicalactivationproperties,andtheMgTi0.2Nialloyelectrodeexhibitedthebestcycleperformance.TheinitialdischargecapacityoftheMgTi0.2Nialloyreachedupto401.1mAh·g-1,andtheretentionrateofcapacitywas31.0%after30cycles,muchhigherthanthatofMgNi(17.3%).TheTafelpolarizationcurvesrevealedthatTiadditioncouldenhancetheanticorrosionperformanceofthesealloysinalkalisolution,whichwasresponsiblefortheamelioratedcyclicstabilityofthesealloyelectrodes.
简介:0Cr18Ni9不锈钢薄壁产品在酸洗过程中易发生过腐蚀。本研究采用0.1mm厚度0Cr18Ni9不锈钢带,对酸洗的各影响因素进行试验研究,结果表明:材料状态不同,耐腐蚀能力不同,退火态更易出现过腐蚀;酸液温度、浓度及酸洗的时间均对不锈钢带腐蚀程度和力学性能有较大影响;在含HF的腐蚀剂中酸洗容易使薄壁不锈钢带力学性能降低,造成材料脆化,且HF含量越高对薄壁不锈钢力学性能影响越大。
简介:ThestructureandelectrochemicalpropertiesofanewlowcobalthydrogenstorageelectrodealloysLa1-xLixNi3.2Co0.3Al0.3(0≤x≤0.2)wereinvestigatedwithadifferentadditionsofLiinreplacementofLa.WiththeincreaseofLicontentsthemaximumdischargecapacityincreasesfrom240mAh·g-1(x=0)to328.4mAh·g-1(x=0.1)andthecyclestabilityisimprovedcorrespondingly.ThecapacitydecaycanremaiN28.6%(x=0.2)after230charge/dischargecycles.Thehighratedischarge(HRD)abilityofthealloys(x≤0.1)isimprovedandthebestHRDis34.1%(x=0.1)underthedischargecurrentdensity1200mA·g-1.ItisfoundthatthepreparedalloysarebasicallycomposedofLaNi5asmatrixphaseandLaNi3assecondphase(x≤0.1).ButtheabundanceofLaNi3phasedramaticallydecreaseswithincreasingx.Whenx=0.2,anewphaseAl(NiCo)3isformed.