Microstructure and tribological properties of laser clad Ti2Ni3Si/NiTi intermetallic coatings

Wear resistant Ti₂Ni₃Si/NiTi full intermetallic composite coatings with a microstructure consisting of ternary metal silicide Ti₂Ni₃Si primary dendrites and interdendritic Ti₂Ni₃Si/NiTi eutectic were fabricated on a substrate of 0.2%C low carbon steel by the laser cladding process using Ti-Ni-Si alloy powders as the precursor materials. Microstructure of the coatings was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the laser clad Ti₂Ni₃Si/NiTi intermetallic coatings was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the Ti₂Ni₃Si/NiTi intermetallic coatings have excellent abrasive and adhesive wear resistance under dry sliding wear test conditions because of the unique combination of high yield strength and toughness of the intermetallic compound NiTi and the high hardness, strong covalent dominant atomic bonds and possible strong hardness anomaly of the ternary metal silicide Ti₂Ni₃Si with MgZn₂ type Laves crystal structure.     

Microstructure and wear resistance of TaC reinforced Ni-based coating by laser cladding

The in situ synthesized TaC particulate reinforced Ni-based composite coating was fabricated on a mild steel by laser cladding of powder mixture of Ni60 alloy powder with (Ta₂O₅ + C)-doping. The microstructure and wear resistance of the TaC/Ni60 composite coating were investigated. It is shown that the coating is bonded metallurgically to the substrate and has a homogeneous fine microstructure containing both approximate cubic TaC particle and acicular chromium carbide uniformly dispersed in the dual phase matrix of γ(Ni) solid solution and eutectic of Cr₃C₂, Fe₂B with γ(Ni). Compared to a Ni60 coating, the hardness of the TaC/Ni60 composite coating was enhanced by a factor of 1.38, could achieve a Vicker microhardness of Hv_0.31100. And the wear rate in a block on ring test against hardened steel was reduced by a factor of five. This is attributed to the presence of in situ synthesized TaC particles and their well distribution in the coating.     

激光熔敷NiTi/Ni3Ti金属间化合物复合材料涂层组织及耐磨性

以Ni79Ti21（wt％）合金粉末为原料,采用同步送粉激光熔敷技术在BT20钛合金表面制备出NiTi／Ni3Ti金属间化合物复合材料涂层,分析了该涂层的显微组织,测试了该涂层的室温干滑动磨损性能。结果表明,激光熔敷涂层组织均匀致密,与基材呈良好的冶金结合,具有优良的抗滑动磨损性能。     

Morphological evolution of primary TiC carbide in laser clad TiC reinforced FeAl intermetallic composite coating

1　INTRODUCTIONIronaluminumbasedonFeAlintermetallicalloywasexpectedtobeanimportantandpotentialhightemperaturematerial,becauseitsgoodresistancetooxidationandcorrosion ,lowdensityandhightem peraturemelting point[12 ] .However ,theintrinsicpropertiesofFeAlintermetallicalloy ,suchaslowductilityandlowfracturestrength ,limiteditsindus trialapplications .Howtoimprovemechanicalproper tiesofFeAlintermetallicalloyandexpanditsindus trialapplicationrealmwasanimportantresearchas pectformaterialworke…     

Sliding wear resistance of TiCp reinforced titanium composite coating produced by laser cladding

Titanium metal matrix composite coatings (MMC) are considered to be important candidates for high wear resistance applications. Laser cladding (LC) by coaxial powder feeding is an advanced coating manufacturing process, which involves laser processing fine powders into components directly from computer aided design (CAD) model.In this study, the LC process was employed to fabricate TiC particle reinforced Ti6Al4V MMC coatings on Ti6Al4V hot rolled samples.The experimental results show that during LC process, TiC particles are partially dissolved into melted Ti-base alloy and precipitated in the form of TiC dendrites during cooling.Dry sliding wear properties of these MMC layers have been compared with substrate materials wear. The observed wear mechanisms are summarized and related to detailed microstructural observations. The layers have been found to show improved tribological properties connected with the TiC_p addition and the LC process parameters.     

Microstructure and wear properties of TiC/FeCrBSi surface composite coating prepared by laser cladding

Titanium carbide particles reinforced Fe-based surface composite coatings were fabricated by laser cladding using a 5 kW CO₂ laser. The microstructure, phase structure and wear properties were investigated by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction, as well as dry sliding wear test. The results showed that TiC carbides were formed via in situ reaction between ferrotitanium and graphite in the molten pool during the laser-clad process. The morphology of TiC is mainly cubic and dendritic form; and the TiC carbides were distributed uniformly in the composite coating. The TiC/matrix interface was found to be free from cracks and deleterious phases. The coatings reinforced by TiC particles revealed higher wear resistance and lower friction coefficient than that of the substrate and FeCrBSi laser-clad coating.     

TC4钛合金表面激光熔覆WC增强镍基复合涂层的组织及耐磨性

为提高TC4钛合金的耐磨性,利用激光熔覆技术(laser cladding,LC)在TC4钛合金表面制备Ni60+50%WC(体积分数)和deloro22(d22)粉末打底+(Ni60+50%WC)2种耐磨复合涂层。采用扫描电子显微镜(SEM)、能谱仪(EDS)以及X射线衍射仪(XRD)来表征涂层的微观结构和物相组成;使用HV-1000显微维氏硬度计、HRS-2M型高速往复摩擦磨损试验机和WDW-100D电子万能试验机来分析涂层的性能。结果表明:2种涂层均由W₂C、TiC、Ni₁₇W₃、Ni₃Ti和Ti_xW_1-x相组成,2种涂层不仅与基体呈现出优异的冶金结合,而且组织均匀致密,没有裂纹瑕疵;由于涂层中存在着原位合成的硬质相和细晶强化共同作用使得涂层硬度显著提高,约为TC4基体的2.82倍;2种涂层的摩擦系数(COF)和磨损量都远低于TC4钛合金基体;Ni60+50%WC复合涂层和d22粉末打底+(Ni60+50%WC)复合涂层的抗剪切结合强度分别为188....     

激光熔覆高铌Ti-Al金属间化合物复合涂层的原位反应机制及其微结构特征

通过激光熔覆增技术在BT3-1钛合金表面制备了高铌Ti-Al金属间化合物复合涂层。根据差热(DTA)和热重(TG)曲线,探讨了氩气和氮气保护下Ti、Al、Nb三种元素混合粉末之间的激光原位合成反应机制。借助X射线衍射(XRD)和扫描电镜(SEM)分析了复合涂层的物相结构和微观形貌。结果表明：复合涂层主要由单质Nb、金属间化合物γ-TiAl、α₂-Ti₃Al和Ti₃Al₂等物相组成,Nb只有部分发生了原位反应。N₂能够降低Ti-Al二元反应之间的反应温度,提高反应速率,对Ti-Al二元反应起催化作用。复合涂层中没出现通常激光熔覆所具有的外延生长柱状晶组织,而是形成了细小的等轴晶组织。     

Microstructure and wear property of laser-clad Co3Mo2Si/Coss wear resistant coatings

Novel wear resistant Co₃Mo₂Si/Co_ss coatings consisting of a microstructure of hard and strong Co₃Mo₂Si intermetallic phases embedded in the ductile Co-base matrix were fabricated on austenite stainless steel by the laser cladding process from the Co-Mo-Si powder blend precursor. The microstructures of the coatings were characterized by optical microscopy (MO), X-ray diffraction (XRD), and scanning electron microscopy (SEM) with an energy-dispersive X-ray analysis (EDX). The wear resistance of the coatings was evaluated in a dry sliding wear test condition at room temperature. Results indicated that the laser-clad Co₃Mo₂Si/Co_ss coatings exhibited very excellent wear resistance against abrasive and adhesive wear.     

SiCp增强铝基复合激光熔覆层组织和磨损性能研究

采用CO2激光器在ZL102合金表面熔覆SiCp-Al基复合涂层,利用SEM和XRD等分析了激光熔覆层的微观组织,测试了激光熔覆层的硬度和磨损性能.结果表明,激光熔覆层表层呈过共晶组织形态,由针状Si、α-Al Si共晶和少量的SiC颗粒组成,底层呈亚共晶组织形态,由α-Al树枝晶,α-Al Si共晶和SiC颗粒组成.激光熔覆层与基材结合区组织为定向生长的树枝晶,且与基材呈联生结晶特征.激光熔覆层的硬度在220～280HV之间,显著提高了ZL102合金的耐磨性能.     

Microstructure and high-temperature wear behavior of laser clad Ni-Ti-Si ternary metal silicide coatings

Ni-Ti-Si ternary metal silicide coatings were fabricated on AISI 304 stainless steel by laser cladding process. The coatings consisted of Ni₁₆Ti₆Si₇ primary dendrite and interdendritic Fe-Ni-based solid solution γ and exhibited excellent abrasive and adhesive wear resistance under high temperature metallic dry sliding wear conditions. The excellent wear properties were attributed to the high hardness and covalent dominant atomic bond of the metal silicide Ni₁₆Ti₆Si₇. The dominant wear mechanism of the coating were delamination of the coating and material transfer from the mating surface.     

激光熔覆WC/Co-Cr合金涂层的组织及耐磨性

采用YAG固体激光器于45钢表面熔覆WC/Co-Cr合金涂层,对涂层的微观组织及界面结构进行了分析。探讨了不同WC添加量对涂层硬度及摩擦磨损性能的影响。结果表明,涂层主要由CrCo、WC以及W₂C相组成,还含有一定的Co的固溶体以及Cr₇C₃相。涂层微观组织呈大致等轴的细小网状共晶组织,涂层与基体呈冶金结合,表面硬度在1100 HV0.02左右。WC含量对涂层硬度以及磨损性能影响较大,呈显著的磨粒磨损机制。但当WC含量增加到20wt%以后,表面微裂纹增多,脆性增大,对使用寿命有不利影响。     

TC4钛合金表面激光熔覆复合涂层的组织和耐磨性

采用5 kW横流CO₂激光器,在TC4钛合金表面熔覆TiC、TiB₂与Ni的混合粉末,制备了无气孔、无裂纹、组织均匀致密的复合涂层。用SEM、EDS、XRD、显微硬度计以及立式万能摩擦磨损试验机分析了激光熔覆层的显微组织、成分和物相,测试了激光熔覆层横截面显微硬度,以及覆层耐磨性能。结果表明,激光熔覆复合涂层与基体呈冶金结合;熔覆层组织从表层到结合区呈现出由棒状、块状向树枝状、颗粒状转变的趋势,且主要由Ti、TiC、TiB、Ti₂Ni、TiNi等相组成;熔覆层显微硬度最高可达863 HV0.2,为基体的2.5倍;熔覆层耐磨性能较TC4钛合金明显提高。     

激光熔覆Fe/NiCr-Cr3C2复合涂层的组织和磨损性能

利用激光熔覆技术在GCr15 钢表面制备Fe/NiCr-Cr₃C₂复合涂层,研究不同NiCr-Cr₃C₂含量对铁基涂层微观组织和磨损性能的影响。结果表明:随NiCr-Cr₃C₂含量的增多,复合涂层显微组织逐渐细化,在铁基合金里掺入NiCr-Cr₃C₂金属陶瓷粉末导致复合涂层里残留奥氏体含量增多,α-Fe相含量减少,截面硬度显著降低。当加入10%NiCr-Cr₃C₂时,复合涂层中出现较多的Cr₃C₂和Cr₂₃C₆硬质相,同时磨痕表面生成了具有减摩作用的氧化产物,从而降低了磨耗和摩擦阻力,使涂层表现出最佳的耐磨性能。     

激光熔覆Ni-Si金属硅化物复合材料涂层显微组织与耐蚀性

以Ni,Si,Cr元素粉末为原料 ,利用激光熔覆技术在A3钢表面制得了Ni Si金属硅化物复合材料涂层。分析了该涂层的显微组织 ,采用测定阳极极化曲线的方法评价了该涂层在 0 .5mol/LH2 SO4 及 3 .5 %NaCl水溶液中的耐蚀性能。结果表明 :激光熔覆Ni Si金属硅化物复合材料涂层组织由Ni2 Si初生胞状树枝晶及枝晶间少量FeNi/Ni31Si12 共晶组成 ,涂层表面平整、组织细小、与基体间为完全冶金结合 ;涂层组织显微硬度在HV80 0～ 95 0之间且沿层深分布均匀 ;由于涂层组织组成相Ni2 Si和Ni31Si12 等本身均具有很好的耐蚀性并具有快速凝固细小均匀的显微组织 ,激光熔覆Ni Si金属硅化物复合材料涂层在 0 .5mol/LH2 SO4 及 3.5 %NaCl水溶液中均表现出优良的耐蚀性能。激光熔覆Ni Si金属硅化物复合材料涂层可望成为一种很有发展前景的耐蚀涂层新材料。     

钛合金激光熔覆TiB-TiC增强TiNi-Ti2Ni金属间化合物复合涂层的组织和耐磨性（英文）

以Ti＋Ni＋B4C粉末混合物为原料,利用激光熔覆技术在TA15钛合金基材表面制得TiB-TiC共同增强TiNi-Ti2Ni金属间化合物复合涂层。采用OM、SEM、XRD、EDS及AFM等手段分析激光熔覆涂层的显微组织及磨损表面,测试涂层的室温干滑动磨损性能。结果表明,激光熔覆TiB-TiC增强TiNi-Ti2Ni金属间化合物复合涂层熔覆具有独特的显微组织,菊花状的TiB-TiC共晶均匀分布在TiNi-Ti2Ni双相金属间化合物基体中。由于高硬、高耐磨TiB-TiC陶瓷相与高韧性TiNi-Ti2Ni双相金属间化合物基体的共同配合,激光熔覆涂层表现出优异的耐磨性。     

Microstructure and properties of Ti–Co–Si ternary intermetallic alloys

Ti–Co–Si ternary intermetallic alloys with Ti₅Si₃ as the main reinforcing phase and intermetallic TiCo as the toughening matrix were fabricated by the laser-melting deposition (LMD) process. Microstructure of the intermetallic alloys was characterized by OM, SEM, XRD and EDS. High-temperature oxidation resistance of the alloys was evaluated by isothermal oxidation at 1173 K and metallic dry-sliding wear property was evaluated at room temperature. The effect of reinforcing phase Ti₅Si₃ content on hardness, oxidation and wear resistance of the alloys was investigated. Results indicate that microstructure of the alloys transforms from hypoeutectic to hypereutectic, while hardness and oxidation resistance increases with the increasing Ti₅Si₃ content. The alloys have good oxidation resistance at 1173 K and the oxidation kinetic curves are approximately parabolic. Wear resistance of the alloys is insensitive to the microstructure and is up to 15–19 times higher than the hardened tool steel 1.0%C–1.5%Cr under dry-sliding wear test conditions. The excellent wear resistance of alloys is attributed to the effective reinforcement of Ti₅Si₃ and the excellent toughness of the intermetallic TiCo.     

TiAl合金激光熔覆复合材料涂层耐磨性研究

利用预涂NiCr-Cr3C2复合粉末对γ-TiAl合金（简称TiAl合金）进行激光熔覆处理,制得了以Cr7C3、TiC硬质相为耐磨增强相,以γ-NiCrAl镍基固溶体为基体的复合材料涂层,研究了原始TiAl合金和激光熔覆涂层的室温和高温（600℃）滑动磨损性能,并讨论了原始TiAl合金和所制备涂层的室温和高温滑动磨损机理。结果表明：激光熔覆复合材料涂层均具有较好的室温和高温滑动磨损耐磨性。室温下涂层的耐磨性先随着其中硬质耐磨增强相体积分数的增加而提高,但当耐磨相体积分数过高时,由于涂层脆性增大,其耐磨性反而下降。     

纯铜表面激光熔覆铜合金涂层的组织及耐磨性

采用光学显微镜、扫描电镜、X射线衍射及能谱分析对纯铜表面送粉激光熔覆制备的铜合金涂层进行了分析.结果表明,涂层与基体为冶金结合,无气孔、裂纹等缺陷,涂层稀释率极低,铜合金涂层在凝固过程中通过液相分离形成大量均匀弥散分布的细小球形分离相、富含铜的固溶体和少量大块分离相聚集体;细小分离相的平均直径小于5μm,分离相由富含Fe、Co、Mo的多元金属硅化物组成.富含铜固溶体的硬度为280 HV0.1,大块分离相聚集体的硬度为510 HV0.1.磨损试验结果表明,激光熔覆涂层的耐磨性较纯铜基体有显著提高.     

铸造碳化钨粉末物性对激光熔覆陶瓷颗粒增强Fe基复合材料耐磨性能的影响

为研究铸造碳化钨粉末物性对激光熔覆陶瓷颗粒增强Fe基复合材料耐磨性能的影响,将不同制备方法和粒径的铸造碳化钨粉末添加到Fe基合金粉中,在45号钢表面进行激光熔覆以获得高硬度和高耐磨的合金化层。利用金相显微镜、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、硬度计分别分析了合金化层的显微组织、物相组成以及显微硬度。利用轮式磨损试验机测试了其常温下的耐磨性能,并进行了比较。结果表明:熔覆层主要由莱氏体组成,碳化钨粉末的制备方法和粒径差异对复合材料的耐磨性能具有重要影响。等离子旋转电极雾化法制备的碳化钨粉末能起到最好的增强耐磨作用,粒径细的碳化钨粉末比粒径粗的粉末增强耐磨效果要好。