激光涂复层质量控制研究

本文对激光涂复层外面及内部质量进行了系统的研究。分析总结出了影响涂层质量的主要因素，及防止涂层缺陷提高涂层使用性能的有效手段。

激光涂复层裂纹及其磨损性质的研究

本文着重对激光涂复层裂纹及其形成机理进行了研究，并分析探讨了涂复层裂纹倾向对其耐磨性的影响关系。为球墨铸铁激光涂复涂层材料的选择以及激光涂复工艺的制定提供实用性经验。

45#钢的NiCrBSi激光涂复

应用２ｋＷ－ＣＯ２激光器在４５＾＃钢板上进行顾ＮｉＣｒＢＳｉ合金的激光涂复处理。使用透射电镜和Ｘ射线衍射进行分析的结果表明整个激光区的相组成是相同物，而在熔楷区与基体交界的过渡层的相组成则与熔化区的有所不同。

激光工业应用

TGl56.99 96010235激光涂复层质量控制研究=The investigationabout quality control of laser cladding layer[刊,中]/冯志刚,殷一贤,邹至荣,汤富荣(重庆大学.四川,重庆(630044))∥激光杂志.—1995,16(3).—118—126对激光涂复层外观及内部质量进行了系统的研究。分析总结出了影响涂层质量的主要因素。

Synthesis of Y_2O_3 particle enhanced Ni/TiC composite on TC4 Ti alloy by laser cladding

A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.

Microstructure and wear resistance of laser clad TiB-TiC/TiNi-Ti_2Ni intermetallic coating on titanium alloy

A wear resistant TiB-TiC reinforced TiNi-Ti2Ni intermetallic matrix composite coating（TiB-TiC/TiNi-Ti2Ni） was prepared on Ti-6.5Al-2Zr-1Mo-1V titanium alloy by the laser cladding process using Ti＋Ni＋B4C powder blends as the precursor materials.Microstructure and worn surface morphologies of the coating were characterized by optical microscopy（OM）,scan electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive X-ray analysis（EDS） and atomic force microscopy（AFM）.Wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature.The results indicate that the laser clad coating has a unique microstructure composed of flower-like TiB-TiC eutectic ceramics uniformly distributed in the TiNi-Ti2Ni dual-phase intermetallic matrix.The coating exhibits an excellent wear resistance because of combined action of hard TiB-TiC eutectic ceramic reinforcements and ductile TiNi-Ti2Ni dual-phase intermetallic matrix.

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-12 Co 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-12 Co composite powders partially melt in liquid Co and 304 stainless steel matrix, and then new carbides consisting of lamellar WC and herringbone M3 W3 C(M=Fe,Co) were formed. Meanwhile, WC-12 Co 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 HV0.3 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.

Effect of Fe content on microstructure and mechanical properties of Cu-Fe-based composite coatings by laser induction hybrid rapid cladding

To select the proper composition and obtain an overall material?microstructure?property relationship for Cu?Fe alloy, theeffect of Fe content on microstructure and properties of Cu?Fe-based composite coatings by laser induction hybrid rapid claddingwas investigated. Microstructure characterization of the composite coatings was tested utilizing SEM, XRD and EDS. Microhardnessmeasurement was executed to evaluate the mechanical properties of the composite coatings. The results show that for low Fe content,the composite coating presents a feature that Fe-rich equiaxed dendrites are embedded in the Cu-rich matrix. With increasing Fecontent, the Fe-rich particles are dispersed in the Cu-rich matrix. With further increasing Fe content, large amounts of Cu-richparticles are homogeneously dispersed in the interdendrite of the Fe-rich matrix. Correspondingly, the average microhardness of thecomposite coatings increases gradually with the increase of Fe content and the microhardness of Cu14.5Fe83Si2C0.5 coating is muchtwice higher than that of the substrate.

Laser in-situ synthesis of titanium matrix composite coating with TiB-Ti network-like structure reinforcement

To avoid high crack sensitivity of TiB-Ti composite coating during laser cladding process,network-like structure composite coating was fabricated with laser in-situ technique on titanium alloy using 5 μm TiB2 powder as the cladding material.The microstructure,phase structure and properties of the coatings were analyzed by SEM,XRD,EPMA,TEM,hardness tester and fretting wear meter.It was observed that the outer ring of the network-like structure was mainly TiB strengthening phase,while the inner ring was α-Ti grain,and the interface between TiB and Ti matrix was very clean and had a consistent orientation relationship.The hardness of the cladding layer with network-like structure gradually decreased from the surface toward the interface,but the average hardness was nearly two times that of the substrate.In the fretting wear test,it was found that the wear resistance of the cladding layer with network-like structure was larger than that of the substrate under low load(40 N).The results revealed that the hardness and fretting wear resistance of the titanium-based composite coating could be improved by the introduction of network-like structure.

Wear and corrosion properties of laser cladded Cu_(47)Ti_(34)Zr_(11)Ni_8/SiC amorphous composite coatings on AZ91D magnesium alloy

To improve the wear and corrosion properties of AZ91D magnesium alloys,Cu-based amorphous composite coatings were fabricated on AZ91D magnesium alloy by laser cladding using mixed powders of Cu47Ti34Zr11Ni8 and SiC.The wear and corrosion behaviours of the coatings were investigated.The wear resistance of the coatings was evaluated under dry sliding wear condition at room temperature.The corrosion resistance of the coatings was tested in 3.5%(mass fraction) NaCl solution.The coatings exhibit excellent wear resistance due to the recombined action of amorphous phase and different intermetallic compounds.The main wear mechanisms of the coatings and the AZ91D sample are different.The former is abrasive wear and the latter is adhesive wear.The coatings compared with AZ91D magnesium alloy also exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.

润湿性对涂复质量的影响

涂层材料与基材之间的润湿能力决定了激光涂层组织的质量,尤其是预置涂层的激光涂复。其润湿能力强的材料在激光涂复后能与基材形成致密、无气孔的表面涂层。反之,则在涂层内出现许多空洞和气隙。