激光熔敷Ni基合金涂层的结构与性能

观测了激光熔敷NiCrBSi合金涂层的显微结构，研究了涂层与不锈钢基体的结合方式和时效处理对其组织结构和显微硬度的影响．用5kW连续二氧化碳激光器对不锈钢上等离子喷涂NiCrBSi合金层进行重熔．涂层的显微结构为细化树枝晶，由γ基体与γ／γ'和NiB的共晶组成．面心立方γ基体品格常数是0．3572nm．时效处理后的合金层由析出γ’沉淀强化相的针状和羽毛状马氏体组成，时效使显微硬度值显著提高．     

高温合金表面激光熔敷热障涂层组织结构与氧化性能

采用 5KW连续CO2 激光器对Ni基高温合金上二次重熔NiCoCrAlY和ZrO2 陶瓷层进行了研究。结果表明 :激光快速熔化和凝固获得定向外延生长、紧密堆积的柱状晶氧化锆陶瓷层。NiCoCrAlY结合层与柱状晶之间存在氧化铝层 ,保证了柱状晶与NiCoCrAlY层的联结。扫描电镜和电子探针联合分析发现 ,氧化锆层与NiCoCrAlY结合层、结合层与基体间均为冶金结合。采用化学改性氧化锆消除了涂层裂纹。高温氧化性能测试得出激光重熔试样氧化动力学近似地遵守抛物线速率方程。在 12 0 0℃ ,空气下激光熔敷TBCs 抗氧化性明显高于等离子喷涂TBCs。     

高温合金表面激光熔敷热障涂层组织结构与氧化性能

采用5KW连续CO2激光器对Ni基高温合金上二次重熔NiCoCrAlY和ZrO2陶瓷层进行了研究。结果表明，激光快速熔化和凝固获得定向外延生长，紧密堆积的柱状晶氧化锆陶瓷层。NiCoCrAlY结合层与柱状晶之间存在氧化铝层，保证了柱状晶与NiCoCrAlY层的联结。扫描电镜和电子探针联合分析发现，氧化锆层与NiCoCrAlY结合层，结合层与基体间均为冶金结合，采用化学改性氧化锆消除了涂层裂纹。高温氧化性能测试得出激光重熔试样氧化动力学近似地遵守物线速度方程，在1200℃，空气下激光熔敷TBCs抗氧化性明显高于等离子喷涂TBC。     

铝合金表面激光熔敷铜基复合材料涂层的工艺和组织

在ＺＬ１０４铝合金表面激光熔敷铜基混合粉末（ｗ（Ｂ）／％：２０Ｎｉ,８．０Ｃｏ５．０Ｆｅ,６．８Ｍｏ,１．５Ｃｒ,３．５Ｓｉ,０．２ＲＥ,其余为Ｃｕ）,制备了高硬度铜基复合材料涂层。研究发现,熔敷层稀释率随光宽度和扫描速度增大而减小,随激光束产大而显著增大;     

金属雾化喷嘴表面热障涂层结构特征研究

采用5KW连续CO2激光器对经等离子喷涂的NiCoCrAlY结合层和ZrO2陶瓷层进行二次重熔处理，并利用金相显微镜，扫措电镜和电子探针对激光熔敷涂层进行了显微结构和元素分布观察与测试，结果表明：激光熔敷涂层中基体对NiCoAlY合金层产生稀释，形成成分和组织偏析。加入了TiO2-Al-Ti添加剂的ZrO2陶瓷层激光重熔后得到了无裂纹的定向生长柱状晶，并且呈现一次枝晶平均间距为2．3μm的表层和平均间距为3．8μm的次表层结构。     

铸铁表面激光熔敷镍基合金涂层的耐磨性研究

为了提高铸铁的耐磨性，以35％WC和不含WC的镍基合金粉末为原料对铸铁表面进行激光熔敷处理，利用XRD、SEM、TEM等技术分析了涂层的成分及显微组织结构，并测试了涂层的耐磨性和硬度．结果表明：激光处理后表面迅速熔化和冷却，组织由珠光体 片状石墨组织转化为不同粗细的针状马氏体与残余奥氏体组织；熔敷层的耐磨性和硬度明显提高，且添加35％WC硬质颗粒的熔敷层硬度最高值不在最表层，而在距表面约0．2mm处；合金涂层在磨损机制下表现为犁沟切削、微切削以及硬相质点的剥落，不同基体划痕形式不同。     

激光熔覆玻璃涂层

本文研究在Ａ３钢基材上激光熔覆玻璃涂层的可行性，激光熔覆玻璃涂层的过程是玻璃熔体在基材表面上湿润、铺展，然后冷凝的过程。玻璃熔体在基材表面上铺展，不仅与它们之间的浸润有关，而且与玻璃熔体的流动性有关。玻璃熔体的流动性在熔覆过程中随时间变化；激光处理参数的不同会改变熔体的随时间变化过程。合理选择激光参数能熔覆形成均匀的、光滑的、粘附的、无裂纹的玻璃涂层。在激光熔覆过程中，会在玻璃熔体中出现结晶现象，     

激光熔覆生物陶瓷复合涂层

介绍在奥氏体型不锈钢基材上预置涂覆具有一定梯度的生物陶瓷粉末（ＨＡＰ或ＣａＨＰＯ４．２Ｈ２Ｏ＋ＣａＣＯ３）的激光熔覆，经ＳＥＭ，ＥＤＳ，ＸＲＤ分析表明，低输出功率，高扫描速率是获得激光生物陶瓷涂层的主要控制因素，预置涂覆ＣａＣＯ３与ＣａＨ（ＰＯ４）．２Ｈ２Ｏ混合粉末涂层，在于大常规方法合成ＨＡＰ所需比例下，可激光合成含Ｃａ５（ＰＯ４）３（ＯＨ）等生物活性陶瓷的复合涂层，且存在一定量非晶态的自由表面     

激光熔敷钴合金涂层的抗空蚀和冲刷磨损性能

采用激光熔敷方法在20SiMn低合金钢表面制成了Co合金涂层，以两种目前水轮机转用材20SiMn低合金钢和0Cr13Ni5Mo不锈钢作为对比材料，对涂层进行了空蚀，液固两相流冲刷磨损及空蚀和冲刷磨损联合作用实验，采用失重法并结合能谱分析，X射线衍射分析及显微硬度测量等手段研究了涂层的显微结构和在不同形式损伤下涂层的性能并分析了原因。结果表明：在20SiMn低合金钢表面激光熔敷形成的Co合金涂层有良好的抗空蚀性能，这与涂层在空蚀过程中发生的应力诱发马氏体相变密切相关。良好的抗空蚀性能有利于提高涂层抗空蚀和冲刷磨损联合破坏，从而使涂层表现出与0Cr13Ni5Mo不锈钢接近的抗联合损伤性能。     

超声振动对EA4T钢激光熔覆质量和性能的影响

采用超声振动辅助激光熔覆对EA4T钢表面进行修复,利用光学显微镜(OM)、扫描电镜(SEM)和X射线衍射仪(XRD),对比分析超声振动对EA4T钢激光熔覆成形质量、微观组织和物相组成的影响,通过显微硬度仪对熔覆层和基体的显微硬度进行测试。结果表明:超声振动作用下,熔覆层成形质量得到提高,原来方向性较强的枝晶组织被打断、打碎,枝晶偏析程度显著减轻;与此同时,施加超声振动晶粒得到细化,促进Cr₂₃C_6碳化物在枝晶上析出,但并未改变熔覆层物相组成;相比较未施加超声振动,超声振动作用下的熔覆层显微硬度分布更加均匀,平均显微硬度提高126.2HV_0.2,热影响区平均显微硬度下降31.2HV_0.2。     

Effect of laser remelting on the tribological performance of thermal barrier coatings

Gas turbine's efficiency improves as operating temperature is increased. For this reason, metallic components used in turbine engines, for propulsion and power generation, are protected by thermal barrier coatings (TBC). Laser glazing has been used to enhance the oxidation and corrosion resistance of thermally sprayed TBC, but there is no information about the effect of this treatment on the tribological performance. ZrO2(CaO) top coat and NiAIMo bond coating were flame sprayed onto an AlSI 1045 carbon steel. The top coat was laser remelted and a densified ceramic layer was induced in the top surface of the ceramic coating. Both, the as sprayed and the laser remelted top coatings, were formed by cubic ZrO2 with some tetragonal precipitates. The grain size was reduced by the laser treatment. The mechanical properties and the local wear rate were evaluated by depth sensing indentation and scratch tests respectively. The nanoscale wear behaviour was always improved by the laser treatment.     

Microstructural characterization of AISI 431 martensitic stainless steel laser-deposited coatings

High cooling rates during laser cladding of stainless steels may alter the microstructure and phase constitution of the claddings and consequently change their functional properties. In this research, solidification structures and solid state phase transformation products in single and multi layer AISI 431 martensitic stainless steel coatings deposited by laser cladding at different processing speeds are investigated by optical microscopy, Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), orientation imaging microscopy (OIM), ternary phase diagram, Schaeffler and TTT diagrams. The results of this study show how partitionless solidification and higher solidification rates alter the microstructure and phase constitution of martensitic stainless steel laser deposited coatings. In addition, it is shown that while different cladding speeds have no effect on austenite–martensite orientation relationship in the coatings, increasing the cladding speed has resulted in a reduction of hardness in deposited coatings which is in contrast to the common idea about obtaining higher hardness values at higher cladding speeds.     

ZrO2陶瓷-金属梯度热障涂层的显微结构特征

利用等离子喷涂技术制备了ZrO2陶瓷和NiCrAl金属的梯度热障涂层，利用扫描电镜（SEM）、能谱仪（EDS）和电子探针（EPMA）研究了涂层的显微结构和化学成分分布特征。实验发现：梯度过渡层的显微结构明显不同，以金属为主要组分的过渡层主要为层状结构，以陶瓷为主要组分的过渡层层状特征不明显；过渡层化学元素分布不均匀，其中Zr和Mg分布特征相同，Zr与Ni分布位置互补，Cr、Al主要以氧化物形式位于晶粒边界处。     

Microstructural characterization of the failures of thermal barrier coatings on Ni-base superalloys

Abstract

Typical thermal barrier coating (TBC) systems consist of a nickel-base superalloy substrate coated with a MCrAlY or diffusion aluminide bond coat, onto which is deposited a yttria-stabilized zirconia (YSZ) TBC. The bond coats are usually deposited via diffusion aluminizing processes or low pressure plasma spray processes (LPPS). The YSZ can be deposited by air plasma spraying (APS) or electron beam physical vapor deposition (EBPVD). A layer of thermally-grown oxide (TGO), which is usually alumina, forms between the bond coat and YSZ during TBC deposition and subsequent high-temperature exposure. The conventional wisdom is that APS coatings tend to fail in the YSZ and that EBPVD coatings tend to fail at the interface between the TGO and bond coat. However, current research has shown that the situation is much more complex and that the actual fracture path can be a function of the type of bond coat, the type of high-temperature exposure, and coating process parameters. This paper describes the results of a study of the failure of state-of-the-art EBPVD TBCs deposited on NiCoCrAlY and platinum-modified diffusion aluminide bond coats. The failure times and fracture morphology are described as a function of bond coat type. The failure times were found to be a strong function of temperature for both bond coats. The failure for NiCoCrAlY bond coats was found to initiate at defects in the coating, particularly at the TGO/YSZ interface, but the fracture propagated primarily along the TGO–bond coat interface. The failure times and morphologies for platinum-modified diffusion aluminide bond coats depended strongly on bond coat surface preparation. The mechanisms for failure of the two bond coats are described. Also, the effects of modifications to the bond coats and variations in processing parameters on these mechanisms are presented.     

45钢表面激光熔覆CoCrNi中熵合金涂层组织与性能

为探究CoCrNi中熵合金在激光熔覆领域中的应用,以CoCrNi合金粉末作为熔覆粉末,在45钢表面采用同轴送粉法制备合金涂层。利用扫描电镜、X射线衍射仪、显微硬度仪、摩擦磨损实验机和电化学工作站等设备研究了熔覆层微观组织、硬度、耐磨性和耐腐蚀性能。结果表明：熔覆层成形良好,组织均匀致密,组成相主要为FCC单相固溶体;熔池与基体交界处为平面晶,底部靠近中心为柱状晶,顶部分别为胞状晶和等轴晶,3种元素在熔覆层深度方向上的比例几乎相同;熔覆层平均硬度为250HV,摩擦系数、磨损量较基体分别降低了11.7%和36.7%;自腐蚀电流密度略有降低,CoCrNi熔覆层的钝化区域为-150到1 100 mV,表明熔覆层显著提高45钢的耐腐蚀性能。     

飞秒激光不锈钢表面陷光微结构的制备与性能研究

利用飞秒激光在高真空环境下,在316L不锈钢表面两次交叉扫描制备了周期性微纳结构,并研究了微纳结构对波长范围200~900nm的光波的吸收增强能力。样品表面微结构形貌与成分采用扫描电子显微镜(SEM)和X射线衍射仪测试。第1次扫描采用高能流激光,获得了微米级锥状钉结构,表面覆盖了典型的激光诱导周期性表面结构(LIPSS)。然后将样品旋转90°,采用能流为0.02J/cm2的激光进行第2次扫描,路径与第1次扫描相交。第1次扫描的结构中的LIPSS被第2次低能流激光打断纳米颗粒,从而与锥状钉结构结合形成双尺度微结构。反射率测试结果表明,这种双尺度微结构表面的平均反射率约为2.28%,为光滑表面平均反射率的3.42%。结合XRD分析结果,不锈钢表面获得强陷光性能主要归因于飞秒激光制备的微结构。     

TiAl合金表面激光重熔热障涂层组织及抗高温氧化性能

为了进一步提高TiAl合金表面等离子喷涂ZrO2-7%(质量分数)Y203热障陶瓷涂层的性能,采用激光重熔工艺对涂层进行处理,研究了激光重熔对涂层微观组织和抗高温氧化性能的影响.用扫描电镜(SEM)分析了涂层形貌和微观结构,同时对其抗高温(850℃)氧化性能进行了考察.结果表明,等离子喷涂热障陶瓷涂层呈典型的层状堆积特征,有一定的孔隙且分布有微裂纹;经过激光重熔处理后,陶瓷涂层片层状组织得以消失,致密性提高,获得了基本没有裂纹等缺陷的重熔层;整个重熔层包括界面没有明显特征的平面晶和上部沿热流方向生长的柱状晶组织.等离子喷涂热障涂层具有较好的抗高温氧化性能,经过激光重熔后可进一步提高其抗高温氧化能力.