激光熔覆钴基合金和Cr3C2/Co涂层的组织性能

运用5 kWCO2连续激光器在低碳钢表面激光熔覆Cr3C2／Co涂层．研究了其组织、结构、显微硬度及滑动磨损性能，并用激光熔覆钴基合金涂层(Co50)进行了对比试验。结果表明，Co50涂层的显微组织是以亚共晶方式结晶的枝晶组织,Cr3C2／Co涂层组织为未熔Cr3C2颗粒、长杆状、多边形块状Cr的碳化物及其间的细小的枝晶和共晶组织。Co50涂层的主要组成相是．γ-Co及(Cr，Fe)7C3，Cr3C2／Co涂层的主要组成相为．γ-Co，Cr7C3．Cr23C6和Cr3C2等。激光熔覆Cr3C2／Co涂层比Co50涂层具有更高的硬度和耐磨性。     

激光熔覆生物陶瓷涂层及界面的热力学计算

在医用金属材料表面形成一层生物陶瓷是制备高性能、高可靠性生物植入材料的有效途径．采用激光处理技术在钛合金表面同步合成及熔覆了以羟基磷灰石为主的生物陶瓷涂层复合材料，激光熔覆制备生物陶瓷涂层覆界面反应是非常复杂的过程，其中包括很多的化学反应，从物理化学角度对涂层覆界面反应进行热力学计算，计算结果表明：在该实验条件下，完全具备合成羟基磷灰石、磷酸钙等生物陶瓷涂层的热力学条件，而且也满足界面处发生化学反应生成钛酸钙等新相的条件。     

激光熔覆Al2O3陶瓷涂层组织结构

研究了45钢表面激光熔覆等离子Al2O3陶瓷喷涂层的组织结构、硬度及滑动磨损特性。结果表明，等离子喷涂Al2O3陶瓷涂层呈层片状，涂层疏松，由α－Al2O3,ZrO2和γ－Al2O3组成。激光熔覆Al2O3陶瓷涂层致密，由α－Al2O3及ZrO2组成。激光熔覆Al2O3涂层硬度较高，滑动磨损时其耐磨性也明显优于等离子喷涂Al2O3陶瓷涂层。     

激光制备陶瓷热障涂层的研究和发展

论述了激光制备陶瓷热障涂层的研究和发展状况 .激光制备陶瓷热障涂层包括激光重熔和激光熔覆两种方法 .激光重熔等离子喷涂热障涂层可获得等离子喷涂涂层所不具备的外延生长致密的柱状晶组织 ,提高涂层应变容限及热震性能 .激光熔覆可获得自动分层的梯度热障涂层成分及柱状晶组织 ,改善涂层的高温氧化及热震性能 .通过激光工艺参数的优化及涂层体系成分及性能的合理设计 ,可获得优于等离子喷涂 ,接近电子束物理气相沉积的热障涂层性能     

铝合金表面激光熔覆高硅涂层的组织与磨损性能

用7kW横流C02激光器在ZL101铝合金表面激光熔覆高硅涂层。探索不同激光功率熔覆对涂层质量的影响,分析涂层的微观组织,测试涂层的硬度和磨损性能。结果表明：在优化工艺参数下制备出的激光熔覆高硅涂层组织致密、无气孔和裂纹,激光熔覆层中存在大量初晶Si、α-Al树枝晶和共晶组织。涂层与基体结合区处呈现典型的外延生长特征,形成了良好的冶金结合。熔覆层的横截面硬度在HV150～320之间,是基体的2～3倍,并显著提高了基体的耐磨性能。     

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．     

TC4合金表面TiN陶瓷激光熔覆层的组织和耐磨性能

为提高TC4合金的耐磨性能，采用连续波CO2激光在其表面熔覆TiN陶瓷涂层，分析了熔覆层的微观组织结构，对熔覆层的硬度和磨损性能进行了测试．结果表明，TiN激光熔覆层分为两个亚层，表层为TiN熔凝层，由TiN棒状树枝晶组成，底层为TiN和钛合金混凝层，由TiN棒状树枝晶、TiN颗粒和钛合金马氏体组成；TiN激光熔覆层的显微硬度在500—900HV之间，明显地改善了TC4合金的磨损性能．     

激光熔覆铜基自生复合材料设计及其涂层研究

为了提高铝合金的耐磨性，利用铜合金体系存在液相分离现象等冶金性质，在铝合金表面设计了自生铜基复合材料体系，并采用激光熔覆技术对其进行了验证和优化。设计的较理想材料体系为Cu-16Ni-6Fe-8Co-7Mo-4Cr-3Si，由其得到的激光熔覆复合材料中存在大量的自生硬质颗粒增强体，其熔覆涂层具有良好耐磨性，其耐磨性甚至优于汽车发动机缸盖阀门座圈QZ5铸铁合金。     

激光熔覆Ni+Cr_2O_3复合涂层的耐蚀性

研究了激光搭接熔覆Ni+Cr2 O3复合涂层在 0 .5mol/LH2 SO4 +0 .5mol/LNaCl水溶液中的电化学行为 .试验表明Cr2 O3粒子在激光熔池中发生了完全溶解 ,涂层具有胞状枝晶组织特征 .激光熔覆Ni+Cr2 O3复合涂层比单一熔覆Ni合金涂层和 2Cr13马氏体不锈钢基材具有更低的维钝电流密度和更宽的钝化区范围 ,明显改善了在该腐蚀介质中的抗点蚀能力 .     

激光熔覆IN718合金涂层的组织特征、力学性能和热裂纹行为综述

对激光熔覆IN718合金涂层的熔覆涂层微观组织、成分偏聚特征和熔覆层力学性能进行综述,并对激光熔覆IN718合金热处理工艺及热处理后的力学性能、涂层热裂纹特征等进行归纳总结,最后对激光熔覆IN718合金涂层的研究方向提出了展望,指出可在激光熔覆IN718合金涂层的加工成形、微观组织、高温力学性能和热腐蚀等方面开展进一步研究。     

激光熔覆及其在石油机械中的应用现状

阐述了目前国内外激光熔覆处理设备的发展状况、当前激光熔覆金属陶瓷涂层所常使用的涂层材料、激光涂层时所采取的主要方法及其工艺比较、熔覆区的组织特征及影响因素、硬度与耐磨性及其它表面性能的改善，概括叙述了激光涂层的主要技术特点以及在石油机械行业中的应用现状，指出了该技术在实际应用中所存在的问题并分析了原因。     

Dry wear behaviors of wear resistant composite coatings produced by laser cladding

Using different proportional mixtures of Ni-coated MoS2, TiC and pure Ni powders, new typical wear resistant and selflubricant coatings were formed on low carbon steel by laser cladding process. The microstructures and phase composition of the composite coatings were studied by SEM and XRD. The typical microstructure of the composite coating is composed of multisulfide phases including binary element sulfide and ternary element sulfide, γ-Ni, TiC and Mo2C. Wear tests were carried out using an FALEX-6 type pin-on-disc machine. The friction coefficient and mass loss of three kinds of MoS2/TiC/Ni laser clad coatings are lower than those of quenched 45 steel, and the worn surfaces of the laser cladding coatings are very smooth. Because of high hardness combined with low friction, the laser cladding composite coating with a mixture of 70% Ni-coated MoS2, 20%TiC and 10% pure Ni powder presents better wear behaviors than the composite coating with other powder blends. The composition analysis of the worn surface of GCr15 bearing steel shows that the transferred film from the laser cladding coating to the opposite surface of GCr15 bearing steel contains an amount of sulfide, which can change the micro-friction mechanism and lead to a reduced friction coefficient.     

低碳钢表面激光涂覆WC+Co的工艺研究

本文研究了利用激光作为热源在低碳钢表面涂覆WC+Co的工艺。利用光镜、扫描电镜、能谱成分分析及显微硬度等手段对涂层合金的组织和性能进行了分析。认为在低碳钢表面涂覆硬质合金的涂层组织性能取决于激光涂覆工艺与预涂层的质量。在较低的激光输出功率和较慢的扫描速率下,可以得到WC颗粒弥散分布于γ为基的固溶体上的组织,其硬度可达1400HV.较高的功率条件下,涂层组织是WC全部熔解重新生成的η+γ共晶组织,硬度降至1000HV.较快的扫描下涂覆层合金不易涂覆在基体上。     

Pulsed Nd：YAG laser cladding of high silicon content coating on low silicon steel

A pulsed Nd:YAG (yttrium aluminum garnet) laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), with associated energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The microhardness was also measured along the depth direction of the specimens. A crack-and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized sin-gle-track and multi-track laser cladding. The phases of the coating are α-Fe, γ-Fe, and FeSi. The high microhardness of the la-ser-cladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt/ in the single-track cladding and 6.5wt/ in the multi-track cladding, respectively.     

Laser cladding Al-Si/Al2O3-TiO2 composite coatings on AZ31B magnesium alloy

To improve the wear resistance and corrosion resistance of magnesium alloys, a 5 kW continuous wave CO₂ laser was used to investigate the laser surface cladding on AZ31B magnesium alloys with Al-Si/Al₂O₃ -TiO₂ composite powders. A detailed microstructure, chemical composition, and phase analysis of the composite coatings were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The laser cladding shows good metallurgical bonding with the substrate. The composite coatings are composed of Mg₁₇Al₁₂, Al₃Mg₂, Mg₂Si, Al₂O₃, and TiO₂ phases. Compared to the average microhardness (50HV_0.05) of the AZ31B substrate, that of the composite coatings (230HV_0.05) is improved significantly. The wear resistances of the surface layers were evaluated in detail. The results demonstrate that the wear resistances of the laser surface-modified samples are considerably improved compared to the substrate. It also show that the composite coatings exhibit better corrosion resistance than that of the substrate in 3.5wt% NaCl solution.     

激光熔覆钛基复合涂层的显微组织和硬度分析

采用激光熔覆快速非平衡合成方法制备了原位反应合成TiB增强钛基复合材料.用Y2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制得TiB/Ti复合涂层.采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能量散射光谱仪(EDS)和硬度测试等方法,研究了原位合成TiB/Ti复合涂层的显微结构和显微硬度.结果显示:激光熔覆层的相结构主要为α-Ti和TiB两相,TiB增强相均匀地分布于复合涂层中,熔覆层的硬度值高于基体Ti合金的硬度值1倍以上,Y2O3含量(质量分数w,全文同)为1％的激光熔覆涂层内部的增强相组织最为均匀、细小,且硬度值也最高,平均硬度(HV)值约为830.     

采用激光重熔改善2Cr13钢的耐酸蚀性能的研究

在２Ｃｒ１３钢的表面进行激光直接扫描重熔,采用现代测试手段对重熔层的组织、成分、结构等进行研究．在酸性介质（１０％Ｈ２ＳＯ４溶液）中对重熔层表面进行电化学腐蚀实验,测定其电化学阳极极化曲线．实验结果表明,采用激光直接扫描重熔来处理２Ｃｒ１３钢表面后,２Ｃｒ１３钢表层的耐酸蚀性能有极大的改善且其耐酸蚀性能与激光重熔工艺有关．     

WC/Ni60激光熔覆复合涂层的强碱腐蚀磨损行为

利用激光熔覆制备WC增强涂层,通过光学显微镜(OM)、电子扫描显微镜(SEM)和EDS对试样观察和分析,并依据颗粒相分布均匀性,获得推荐优化工艺参数是送粉量为7.8g/min、扫描速度为4mm/s、激光功率为2.0kW和离焦量为50mm。在此基础上,应用M-200摩擦磨损试验机考察了WC/Ni60涂层在40% NaOH强碱溶液作用下的摩擦磨损行为,结果表明,涂层的摩擦磨损机制随工况的变化而变化,钝化膜的生成和溶解成为一个动态过程,且所制备的涂层在中速中载时较干摩擦能够显著降低摩擦因数和磨损量。     

热等离子弧熔覆层的耐磨性研究

运用热等离子弧熔覆法,在Q235基体表面熔覆了镍基合金,对合金的组织和形成原因及熔覆层和基体的界面进行了分析研究。实验表明,熔覆层有较好的耐磨性,主要是形成大量高强韧的镍基固溶体和耐磨的硬质相及表面形成的细小组织对耐磨性的贡献,并分析了磨损机理。