Ni基合金表面激光熔覆Co基合金的组织与性能

用同步送粉法，在Ni基合金表面上制取了Hoegan aes Co基合金（HMSP 2537）的激光熔覆层。利用金相显微镜，扫描电镜，X射线衍射仪，显微硬度计对熔覆层的组织，相结构，硬度进行了分析和测试。结果显示，熔覆层的不同区域组织及性能不均匀；激光输入功率增大，枝晶间距增大，硬度降低。     

冷作模具钢激光熔覆Ni基合金组织和性能研究

为提高Cr12MoV模具钢硬度和耐磨性,研究采用激光熔覆技术在其表面制备Ni基合金.研究结果表明,涂层显微组织为异向生长的树枝晶,涂层相结构为γ-(Fe, Ni)、Cr₇C₃、BNi₂以及Ni-Cr-Fe相.由于细晶强化、固溶强化和第二相强化作用,使熔覆层平均硬度比基体硬度提高了175%.涂层摩擦系数为0.2,明显小于基体(0.4),涂层的磨损体积较基体提高1个数量级.     

等离子熔覆WC增强镍基合金涂层组织与性能研究

采用等离子熔覆的方法在低碳钢基体上获得Ni60+35%WC涂层,借助超景深三维显微系统,观察并分析了熔覆层的宏观组织和显微组织,并研究了熔覆层的显微硬度分布,得出了以下结论：所制备的熔覆层成型良好,显微硬度为基体的4～6倍;熔覆层底部存在大量的WC颗粒,硬度较高;随着离熔合线距离的增加,WC逐渐减小,硬度降低;随着电流的增加,熔覆层中,WC的溶解量增加,硬度逐渐降低。     

Cr3C2对激光熔覆Ni基合金涂层组织与性能的影响

采用激光熔覆技术在低碳钢表面制备Ni基合金涂层(Ni50)及添加30％Cr3C2(质量分数)的Ni基复合涂层(Cr3C2/Ni).利用光学显微镜(OP)、扫描电镜(SEM)及X射线衍射仪(XRD)研究2种涂层的微观组织特征和相结构;通过显微硬度以及滑动磨损试验分析两种涂层的硬度和耐磨损性能.结果表明:Ni50合金涂层组...     

钛合金表面激光熔覆Cr3C2/Ni基合金复合涂层的微观组织

将质量分数为25％的Cr3C2／Ni基合金混合粉末预置在TCA合金表面，利用5kW横流CO2激光器进行激光熔覆试验，得到Ni基Cr3C2复合涂层．利用SEM和XRD对熔覆层的微观组织和相组成进行了分析，采用HXD—1000T数字式显微硬度计测量了熔覆层的硬度．结果表明，Ni＋Cr3C2复合涂层存在γ-Ni、TiC、CrTC扑M23（C，B）6和CrB等相，熔覆层硬度在600～900HV之间．     

半导体激光熔覆高硬Ni基WC涂层

为提高球阀的使用寿命,通过激光熔覆技术,在304钢基体上制备Ni28+WC涂层,并研究WC含量和激光器功率对涂层表面性能的影响.借助金相显微镜、显微硬度计研究了不同含量WC下涂层的裂纹情况、稀释率及硬度.研究结果表明:随着WC含量升高,涂层硬度显著提高,稀释率逐渐降低,增加激光输出功率可以促进WC颗粒融化从而提高稀释率,当WC含量为30%时,涂层无裂纹,平均显微硬度达到580Hv0.1,稀释率为4.9%,涂层与基地之间实现冶金结合.WC含量高于40%时,由于未融化和析出的WC颗粒的增多,涂层开裂.     

激光熔覆纳米La2O3/Ni基合金涂层

采用横流5kWCO2激光在低碳钢基体表面制备纳米La2O3/Ni基激光熔覆涂层。采用光学显微镜（OP）、扫描电子显微镜（SEM）、X射线衍射仪（XRD）分别对熔覆涂层进行显微组织和相组成的观察。用显微硬度计和滑动磨损试验机对熔覆涂层的硬度和耐磨性进行测试。试验结果表明：熔覆层主要由γ-（Ni,Fe）,Cr23C6,LaNi10.5Si2.5等相组成,随离结合面距离增大,熔覆层的组织逐渐变细。随着纳米La2O3加入量及扫描速度增加,熔覆层组织变细。加入纳米La2O3后,平均硬度由未加时500HV0.5提高到约700HV0.5,耐磨性也得到不同程度的提高。在本试验条件下,添加质量分数为1.0%纳米La2O3熔覆层的耐磨性明显高于质量分数为1.5%纳米La2O3熔覆层的耐磨性。扫描速率采用250mm/min的熔覆层,其综合性能最佳。     

Q345钢等离子弧熔覆铁基合金涂层组织分析

在Q345钢基体上采用等离子弧熔覆Fe-Ni-Cr-B-Si和Fe-Cr-B-Si两种铁基粉末涂层,制备具有冶金结合的耐磨涂层。采用光学显微镜(OM)、扫描电镜(SEM)等研究熔覆层的组织,采用X射线衍射仪对涂层进行物相分析,利用显微硬度计测试涂层的显微硬度分布。结果表明:Fe-Ni-Cr-B-Si熔覆层主要为柱状γ-Fe,局部区域为α-Fe和碳化物的网状的共晶组织;Fe-Cr-B-Si熔覆层组织主要为胞状晶,局部区域为网状的共晶组织。两种熔覆层与基材均实现了熔化冶金结合,熔覆层与母材呈联生方式长大,熔覆层的显微硬度可达500~570HV0.2,母材热影响区组织为马氏体和珠光体。     

Ti对激光熔覆铁基合金涂层组织和耐磨性的影响

采用激光熔覆技术在低碳钢表面制备Fe基合金涂层（Fe50）和添加1％（质量分数）Ti粉的Ti／Fe50涂层,分析研究两涂层的相结构、显微组织、硬度及耐磨性。结果表明：激光熔覆Fe50涂层主要由α-Fe和Cr23C6组成,其组织由柱状枝晶固溶体及其间网状分布的共晶组成;添加质量分数为1％的Ti后,涂层中除了α-Fe和Cr23C6相,还含有γ—Fe相,组织明显等轴化、均匀化;与Fe50涂层相比,Ti／Fe50涂层耐磨性提高了20％以上。     

实用激光熔覆金属涂层技术的研究

论述激光成形熔覆涂层的机理及其关键技术－物理参数的优化选择，探讨该方法在４０Ｃ撕体零件上的应用，对显微组织和性能进行测试和分析，其机械特性明明显的提高。     

激光熔敷镍基自熔性合金粉末的研制

针对激光熔敷表面处理技术对合金粉末材料性能的要求，分别研究了合金粉末的B含量、Si含量以及B、Si含量配比对激光熔敷的工艺性能、粉末形貌及涂层性能的影响，研制出具有良好的工艺性能和使用性能的激光熔敷用镍基自熔性合金粉末．     

45#钢表面NiCrBSi合金激光熔敷层的组织和硬度

为提高45^#钢表面硬度及耐磨性能，采用激光熔敷技术在其表面制备NiCrBSi合金涂层，利用X射线衍射仪、扫描电镜和透射电镜分析了熔敷层的微观组织，利用显微硬度计测试了熔敷层的硬度，结果表明，激光熔敷层的组织由γ-Ni树枝晶、γ-Ni Ni3B共晶、M7C3树枝晶和CrB颗粒组成，激光熔敷层的硬度在HV800～900之间．     

Microstructure and abrasion wear behavior of Ni-based laser cladding alloy layer at high temperature

Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21 ＋20% WC＋0. 5 % CeO2, Ni25＋20 % WC＋0. 5 % CeO2 and Ni60 ＋ 20 % WC ＋ 0. 5 % CeO2, the experimental results show that Ni21 ＋ 20 % WC ＋ 0.5?O2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.     

Microstructure and wear resistance of in situ NbC particles reinforced Ni-based alloy composite coating by laser cladding

The in situ synthesized NbC particles reinforced Ni-based alloy composite coating was produced by laser cladding a precursor mixture of Ni-based alloy powder,graphite and niobium powders on a steel substrate.The microstructure,phase composition and wear property of the composite coating were investigated by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and dry sliding wear test.The experiment results show that the composite coating is homogeneous and free from cracks,and about 0.8 mm thick.The microstructure of the composite coating is mainly composed of NbC particles,CrB type chromium borides,γ-Ni primary dendrites,and interdendritic eutectics.CrB phases often nucleate and grow on the surface of NbC particles or in their close vicinity.NbC particles are formed via in situ reaction between niobium and graphite in the molten pool during the laser cladding process and they are commonly precipitated in three kinds of morphologies,such as quadrangle,cluster,and flower-like shape.Compared with the pure Ni-based alloy coating,the microhardness of the composite coating is increased about 38%,giving a high average hardness of HV0.21000,and the wear rate of the composite coating is decreased by about 32%,respectively.These are attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.     

Microstructure and corrosion properties of laser cladding MoNi based alloy coatings

Mo-based alloys are widely used for their excellent wear and corrosion resistance as well as high temperature resistance.Mo-NiCrBSi and Mo-Ni alloy coatings were prepared on 1020 water wall tube by laser cladding technology in the present study.The microstructure and phase compositions were analyzed by means of the scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS)and X-ray diffractometry(XRD).The corrosion properties of the coatings were evaluated by an electrochemical experiment at room temperature in 3.5 wt.%NaCl electrolyte.With increasing content of Mo,the structure homogeneity in Mo-Ni coatings deteriorated,the grain size increased,the average hardness and the corrosion resistance declined,due to the more content of harmful phases.Compared to the Mo-Ni coatings,the overall performance was better for the Mo-NiCrBSi,which had the higher hardness contributed by the element B and Si as well as the better corrosion resistance due to the addition of Cr.     

Microstructure and Fractural Morphology of Cobalt-based Alloy Laser Cladding

1　IntroductionCobalt basedalloyiswidelyusedingasturbineair craftenginesandvalvespumpshaftsofpressurevessels[1,2 ] ,duetoitshighflowstressesandoutstandingresistancetooxidationandwearuptotemperaturesclosingtoitsmeltingpoint.Thehighsolidificationrateoflasercladdingtendstoresultinfinemicrostructures ,non equi libriumphasesandsupersaturatedsolidsolutions ,whichleadtohighhardnessandwearandcorrosionresi stance[3 -5] .However,crackingfrequentlyappearsinthelasercladdinglayerwhichlimitstheuseofthissurf…     

Laser cladding of Ni-based alloy on copper substrate

The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope （OM）, scanning electron microscope （SEM）, and X-Ray diffraction （XRD）. The average microhardness of the cladding coating was Hv 280, which was almost three times of that of the Cu substrate （Hv 85）. OM and SEM observations showed that the obtained coating had a smooth and uniform surface, as well as a metallurgical combination with the Cu substrate without cracks and pores at the interface. With the addition of copper into the nickel-based alloy, the differences of thermal expansion coefficient and melting point between the interlayer and cladding were reduced, which resulted in low stresses during rapid cooling. Moreover, large amount of （Cu, Ni） solid solution formed a metallurgical bonding between the cladding coating and the substrate, which also relaxed the stresses, leading to the reduction of interfacial cracks and pores after laser cladding.