激光熔覆和重熔制备Fe-Ni-B-Si-Nb系非晶纳米晶复合涂层

采用激光熔覆和重熔的方法在低碳钢CCS-B上制备Fe-Ni-Si-B-Nb系非晶纳米晶复合涂层。利用X射线衍射、扫描电镜、EDAX能谱及透射电镜分析涂层的物相、组织结构,运用显微硬度计、纳米压痕仪及摩擦磨损试验机研究涂层的显微硬度分布、微观力学性能及摩擦磨损性能。结果表明:熔覆层的组织由表面至基体分为非晶纳米晶复合区、熔覆层与基体,其中,复合区为Fe2B、γ-(Fe,Ni)多晶和非晶相的混合组织;涂层的最高显微硬度达到了1 369 HV;涂层的平均摩擦因数为0.275;涂层的主要磨损形式是磨粒磨损和粘着磨损,具有良好的摩擦磨损性能。     

Fabrication and microstructure of Fe-based amorphous composite coatings by laser cladding

Fe-based amorphous composite coatings were fabricated on AISI 1045 steel by laser cladding. The results of the X-ray diffraction and transmission electron microscopy analyses show the coating is composed of an amorphous phase in majority and a nanocrystalline phase in minority. Phase composition of the coating changes along the depth of the coating. The reasonable scanning speed for fabricating an amorphous composite coating is 3 500mm/min when the laser power is 4 800W and the laser beam diameter is 2mm. If the scanning speed is lower than 3 500mm/min, the intensity of the two main diffraction peaks in X-ray diffraction patterns of the coatings decreases with the scanning speeds increasing. At the same time, a broad halo peak emerges and enlarges. High laser power and fast scanning speed are the essential conditions of amorphization. The coating exhibits high microhardness.     

稀土RE对激光熔覆Fe基非晶复合涂层的影响

研究了稀土RE微合金化对激光熔覆Fe38Ni30Si16B14V2(原子分数,%)非晶复合涂层的影响.使用X射线衍射和扫描电镜分析熔覆层物相、组织结构与RE对非晶相形成的影响.结果表明,激光熔覆条件下,稀土RE的微合金化能提高Fe38Ni30Si16B14V2合金的玻璃形成能力,有利于形成非晶涂层.稀土RE的加入改变了非晶合金的结晶体系,稀土RE加入量为1时促进γ-Fe, Ni相的结晶,抑制Fe2B相的结晶;RE为2时,两种相的结晶均受到抑制.稀土RE的微合金化使涂层的显微硬度值降低,涂层的显微硬度沿涂层厚度方向下降.     

Formation and performance of an Fe-based amorphous-nanocrystalline composite coating by laser cladding and remelting

Abstract

A very important research topic in the area of the surface performance of engineering components, in particular their wear properties, recently has been the application of high quality surface layers on relatively cheap substrates. An Fe-based composite coating with both amorphous and nanocrystalline structures on a mild steel substrate offers a combination of high quality coating and low materials cost, at the same time extending the range of applications of traditional materials. The difficulties posed by preparation of Fe-based amorphous alloys have limited progress for many years. However, the recent development of high power lasers, and of laser material processing technology in general, has made the preparation of a Fe-based amorphous and nanocrystalline composite coatings over a large area a real possibility.     

Wear and corrosion resistance of CoCrNi composite coatings by laser cladding

Two kinds of CoCrNi composite coatings,CoCrNiMo and CoCrNiMo BC,were prepared by laser cladding on the base metal of 304 stainless steel.The wear and corrosion properties of the coatings were studied by wear tests and electrochemical tests.Results show that the addition of B₄C promotes the generation of the ceramic phase,and therefore improving the microhardness of the coating and enhancing its wear resistance,while simutaneously keeps its excellent corrosion resistance.Energy dispers...     

激光熔覆制备Fe-Mo-Ni-Si-B非晶纳米晶复合涂层的性能

利用激光熔覆技术在45钢上制备Fe-Mo-Ni-Si-B涂层,并进行激光重熔处理。借助光学光学显微镜、环境扫描电子显微镜、X射线衍射仪对涂层的组织结构进行研究,并利用维氏硬度计、磨损试验机、电化学工作站等设备分析了重熔前后涂层的显微硬度、摩擦磨损及耐腐蚀性能。结果表明:利用激光熔覆技术能够在45钢上获得冶金结合良好的Fe-Mo-Ni-Si-B非晶纳米晶复合涂层。熔覆层由晶体相和非晶相混合组成,主要的晶体相包括Fe Si、Fe2B、Fe Ni、Fe3Mo及Fe单质。经过重熔处理后,熔覆层组织细化,晶粒更为细小,非晶相比例提高。熔覆层的硬度可达到1007 HV0.1,而重熔层硬度略提高到1076 HV0.1,与基体相比,都提高了5~6倍;与基体相比,熔覆层的耐磨性和耐蚀性得以提高,其中重熔层更是表现出优异的耐磨性和耐蚀性。     

激光熔覆制备Fe基非晶化涂层的研究进展

从Fe基激光非晶化的材料设计和制备工艺两个方面对激光熔覆制备Fe基非晶层的影响进行了分析和阐述.由于激光熔覆制备非晶涂层的工艺条件与传统的大块非晶制备方法有着很大的不同,所以由此带来了材料设计上的不同思路.另外,对于激光熔覆这种效率较高的制备方法,熔覆层的成形对熔覆层的质量至关重要:熔覆材料的流动性、抗氧化性和均匀性对最后熔覆层中非晶形成比例都有着很大影响.对目前适合激光熔覆制备Fe基非晶层的非晶体系作了详细的描述,包括Fe-Ni-B-Si-V、Fe-Co-Ni-Zr-Si-B及Fe-Zr-Ni-Al-Si-B体系等,其中除了基体Fe之外,主要的组分一般都包括了Ni,B,Si,主要是依据了Inoue的经验三原则来设计,另外考虑到材料熔覆层快速成形和抗氧化性能,加入了大量的可以降低熔点的元素以改善熔池流动性.     

Microstructure and properties of WC-12Co composite coatings prepared by laser cladding

A comprehensive study of the phase composition, microstructure evolution, microhardness and wear performance of WC-12Co composite coatings fabricated by laser cladding using coaxial powder-feed mode was presented. It was shown that a combination of high scan speed and high laser energy density made WC on the edge of WC-12Co composite powders partially melt in liquid Co and 304 stainless steel matrix, and then new carbides consisting of lamellar WC and herringbone M₃W₃C (M=Fe, Co) were formed. Meanwhile, WC-12Co composite coatings with no porosity, cracks and drawbacks like decarburization were obtained, showing high densification and good metallurgical bonding with the substrate. Furthermore, a considerably high microhardness of HV_0.3 1500-1600, low coefficient of friction of 0.55 and wear rate of (2.15±0.31)×10^-7 mm³/(N·m) were achieved owing to the synergistic effect of excellent metallurgical bonding and fine microstructures of composite coating under laser power of 1500 W.     

钛合金表面激光熔覆高温自润滑耐磨复合涂层

为了提高钛合金的摩擦学性能,采用激光熔覆技术在Ti-6Al-4V合金表面制备了γ-NiCrAlTi/TiC与γ-NiCrAlTi/TiC/CaF₂复合涂层. 采用 X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)分析了涂层的物相和显微组织,在球-盘式高温摩擦磨损试验机上测试了不同温度下(室温,300 ℃,600 ℃)复合涂层的摩擦学性能. 结果表明,激光熔覆的复合涂层与基体呈冶金结合,γ-NiCrAlTi/TiC/CaF₂复合涂层主要由"原位"生成的小块状,针状TiC颗粒及TiC树枝晶,γ-NiCrAlTi固溶体基体及弥散分布的球状CaF₂颗粒组成. 由于硬质增强相 TiC与增韧相γ-NiCrAlTi的共同作用,γ-NiCrAlTi/TiC与γ-NiCrAlTi/TiC/CaF₂复合涂层的磨损率在试验温度下都远低于Ti-6Al-4V基体;在600 ℃时,γ-NiCrAlTi/TiC/CaF₂涂层的平均摩擦系数为0.21,相对于基体与γ-NiCrAlTi/TiC涂层分别降低了43%,50%,表现出良好的高温自润滑减摩性能.     

激光熔覆反应合成TiC/Al基复合涂层研究

将Al-Ti-C机械混合粉末预涂在ZL102合金表面,采用5 kW横流CO2激光器进行熔覆处理,利用XRD、SEM和TEM等分析和观察了激光熔覆层的微观组织,测试了激光熔覆层的硬度.结果表明,以Al-Ti-C机械混合粉末为原料,可以在激光熔覆过程中反应合成TiC颗粒,反应合成的TiC颗粒尺寸细小(＜5μm),在涂层中分布均匀,与涂层基体金属结合紧密.激光熔覆层的硬度在190～250 HV0.2之间,明显提高了ZL102合金的表面硬度.     

Mechanism of Zr in in situ-synthesized particle reinforced composite coatings by laser cladding

By adding mixture of ZrO_2 and carbon, a Zrenhanced composite coating was produced onto an AISI1045 substrate by laser cladding. The microstructure and phase formation, microhardness and wear resistance of the composite coating were studied. The experimental results indicate that the composite coating with metallurgical bonding to substrate consists of y-Ni, massive ceramic particles of ZrC,NiZr_2, Ni_7 Zr_2,(Fe,Ni)_(23)C_6 and Fe_3 C. The in situ-synthesized ZrC particles are uniformly dispersed in composite coating, which refines the microstructure of composite coating. With different Zr02 and carbon additions, the properties are improved differently. Finally, the fine in situ ZrC particles improve the microhardness of composite coating to HV_(0.2) 650, which is nearly 2.7 times that of Ni25 coating. Also, the composite coating has an advantage in wear resistance; it offers better wear resistance when more mixture of ZrO_2 and carbon was added in nickel alloys.     

Microstructure and properties of Inconel 625 + WC composite coatings prepared by laser cladding

Inconel 625 + WC composite coatings were prepared on the surface of 2Cr13 steel by laser cladding.The microstructure,microhardness and corrosion resis-tance of ...     

Microstructures and properties of Fe-Co-B-Si-Nb coating prepared by laser cladding and remelting

High power laser cladding of [(Fe0.5Co0.5)0.75B0.2Si0.05] 95.7 Nb4.3 powder mixture afier-remelting was performed to fabricate Fe-based metallic glass coating on the surface of steel of China Classification Society:Grade B (CCS-B).Scanning electron microscopy (SEM),X-ray diffraction (XRD),transmission electron microscopy (TEM)with energy dispersive spectrometer (EDS),Vickers hardness tester and corrosion resistance tester were employed to characterize microstructures and evaluate properties of this coating.According to the results of SEM ,XRD and TEM ,the cladding coating consisted of nanocrystalline embedded in amorphous phase.EDS data indicated that Nb segregated in the amorphous matrix.The results of hardness test revealed that the hardness of the top layer was higher than that of the inner layer of the coating.The coating exhibited excellent corrosion resistance in a 3.5% NaCl solution.     

激光熔覆WC颗粒增强复合涂层的组织及耐磨性

为了提高TA15钛合金的耐磨性,在TA15钛合金表面利用激光熔覆预置的大粒度WC颗粒与TA15混合粉末层制备WC颗粒增强耐磨复合涂层。采用金相显微镜(OM)、扫描电镜(SEM)分析涂层的显微组织,采用X射线衍射(XRD)结合能谱(EDS)对涂层进行物相鉴定,测试涂层在二体磨料磨损及室温干滑动磨损条件下的耐磨损性能并分析磨损机理。结果表明:增强相WC颗粒在涂层中较均匀分布,初生(TiW)C/TiC相和(TiW)C+(Ti,W)共晶组织组成增强相的基体,涂层在二体磨料磨损及干滑动磨损条件下表现出优异的耐磨性能,较钛合金基材耐磨性能提高几十至上百倍;WC颗粒与基体中韧性的高硬相及优异的抗粘着性能对涂层耐磨性起主导作用。     

激光熔覆Fe-Ni-Si-B非晶层的形成条件

采用5 kW横流CO2激光器在45钢基体上激光熔覆制备了Fe38Ni32Si16B14的非晶层.利用X射线衍射和透射电镜分析了熔覆层物相、组织结构与非晶形成的影响因素.结果表明,B以硼铁的形式加入有利于非晶层的形成;Si含量为16%时非晶层形成能力达到最大,Si在作为合金组元的同时还起到防止其他元素氧化烧损的作用,其含量影响到合金系的玻璃形成能力;激光功率和光斑直径一定时,扫描速度影响熔池的均匀化程度和冷却速度.在激光功率4 800 W,扫描速度3 500 mm/min时,可以实现激光表面非晶化.     

Mechanism of pool separation and stratification in laser remelting and cladding

1INTRODUCTIONInrecentyears,agreatdealofattentionhasbeenfocusedon1aserreme1ungandcladdingtechnique,whichhavebeenusedextensivelyinindustriesbecause0fimprovingwear-resistance,corrosionresistanceandthermal-barrierofthematerial,.,f...[1'2].Inordert0obtainagoodsurfacecoating,experimentalandnumericalin-vestigationsoncharacteristicsoflaserPOOlwerecarriedonbymanyresearchers.Zax Nicom-positecoatingwasproducedbylasercladdingon4Cr13steelsubstrateandstratifiedstructureincladhasbeenobservedbyPeiet.l[…     

激光熔覆在金属间化合物涂层材料制备中的应用

在分析金属间化合物涂层材料特点的基础上,综述各种激光熔覆合成金属间化合物涂层的研究现状,分析了各种金属间化合物涂层的组织和性能.研究表明,激光熔覆合成的金属间化合物涂层均具有优异的耐磨、耐腐蚀、抗氧化等性能.     

激光熔覆制备Fe-Ti-Mo-C系复合涂层

采用钛铁、钼铁和石墨为激光熔覆粉末,利用激光多道搭接熔覆技术在碳钢基体上制备Fe-Ti-Mo-C复合涂层.利用X射线衍射仪、场发射扫描电镜、电子探针对涂层的相结构和显微组织进行了研究.用显微硬度计和滑动磨损试验机,对涂层的硬度和耐磨性能进行测试.结果表明,涂层中原位生成了(Ti,Mo)C复合碳化物.(Ti,Mo)C呈面心立方结构,晶格常数略小于TiC晶粒.随着原材料中钼铁加入量的增加,涂层显微组织由铁素体、珠光体向马氏体转变,显微硬度和耐磨性增加,但抗裂性能降低.     

Microstructures and mechanical properties of FeCoCrNi high entropy alloy/WC reinforcing particles composite coatings prepared by laser cladding and plasma cladding

FeCoCrNi HEA coatings with 20% mass fraction of WC reinforcing particles were prepared by two different cladding methods, laser cladding (LC) and plasma cladding (PC). The microstructure of HEA matrix and WC particles of LC and PC coatings were discussed respectively. For HEA matrix, dendritic morphology was observed in both coatings. For WC particles, a few granular (Cr,W)₂C carbides around WC particles in LC coatings, and a large number of crystal and fishbone Fe₃W₃C carbides around WC particles in PC coatings. Mechanical properties as hardness and wear resistance of the two kinds of coatings were also investigated. The interstitial solution strengthening effect of C element is stronger in PC coating, and the hardness of HEA matrix in LC coatings is twice that of in PC coating, which shows a strong retention force on WC particles. The friction coefficient of LC coating is lower and stable, with the volume wear rate of 0.7 × 10⁻⁵ mm⁻³/N·m, showing high wear resistance. PC coatings have poor wear resistance due to decarbonization and oxidation of WC particles and reduction of retention force of HEA matrix, with the volume wear rate of 8.29 × 10⁻⁵ mm⁻³/N·m. The wear mechanism of both coatings were also discussed.