氮化钛涂层高速钢刀具磨损特性及磨损规律的研究

本文探讨了涂层高速钢刀具的磨损特性和磨损扩展规律，分析了涂层在各磨损阶段起的不同作用，并说明了在使用涂层刀具时应注意的一些问题     

纳米掺杂对Al2O3＋13wt％TiO2等离子喷涂涂层组织结构及抗磨损性能的影响研究

采用纳米掺杂方法制备纳米包覆微米级粒子的AT-13等离子喷涂粉末，并利用大气等离子喷涂技术制备出含有纳米复相结构的陶瓷涂层。采用常温干摩擦试验评价纳米复相结构涂层的耐磨损性能，并利用扫描电镜（SEM）观察磨损后的磨痕形貌。结果表明，纳米复相涂层的耐磨损性能明显好于传统陶瓷涂层，且磨损载荷高于400N后，纳米复相涂层磨损机制和传统涂层的不同，传统涂层的磨损主要是涂层的微裂纹产生和颗粒的剥落，而相同条件下纳米复相涂层，主要表现为涂层的粘着磨损与局部剥落。     

2种FeCr基高速电弧涂层的组织和耐磨性能对比研究

针对电站锅炉受热面管、风机等构件的耐磨应用场景，应用了不同碳及稀土元素含量的2种FeCr基涂层材料，通过高速电弧喷涂技术在基体20G钢上制备涂层。采用光学显微镜、扫描电子显微镜、X射线衍射仪、白光干涉仪系统表征涂层微观形貌及相组成，通过维氏显微硬度、拉伸结合强度、球-盘摩擦磨损试验检测涂层的力学及耐磨性能。结果表明：2种涂层微观结构均呈典型的层片状结构，由于硼、碳等硬质相元素分布于FeCr固溶体中，使得涂层的硬度远高于基体。高碳含量及稀土元素的添加使得涂层孔隙率由2.22%±0.47%降低至0.92%±0.13%,硬度从(8.05±0.53) GPa增加至(10.47±0.68) GPa,磨损质量损失降低40%。从涂层的磨损形貌来看，高硬度及低孔隙率使得磨损机制由黏着磨损转化为磨粒磨损。通过FeCr基涂层对磨损表面进行防护，可以有效解决电站锅炉部件的磨损问题，保证锅炉机组的安全稳定运行。     

运行状态下风力机叶片涂层沙蚀磨损研究

通过对运行状态下的1.5 MW风力机叶片缩微模型进行冲蚀磨损试验,模拟真实运行状态下风力机叶片涂层的冲蚀磨损过程,研究不同叶轮转速、叶片分区、沙粒粒径对叶片涂层冲蚀磨损量的影响,分析叶尖前缘和近后缘处表面磨损的微观形貌,明确了运行状态下风力机叶片与沙粒之间的相互作用方式及冲蚀磨损机理.运行状态下,风力机叶片涂层冲蚀磨损进程特征依次为麻面、冲蚀坑、冲蚀坑合并、涂层小块剥落和涂层大面积剥落.不同叶轮转速下叶片涂层的冲蚀磨损量虽存在差异,但冲蚀磨损进程有着较高的相似性,可将整个过程分为磨损孕育期、快速磨损期和缓慢磨损期.随着冲蚀区域与叶根距离的增大,叶片涂层的冲蚀磨损量不断增大.不同粒径沙粒冲击叶片涂层,冲蚀磨损进程总体趋势相似,但粒径越小,冲蚀磨损进程的发展越缓慢.沙粒冲蚀前缘处的相对运动可近似为垂直冲击,冲蚀磨损特征主要为近圆形冲蚀坑及横向裂纹扩展下的涂层脱落;冲击近后缘处时,冲蚀磨损程度明显低于前缘处,冲蚀磨损形式主要为凹形压痕及鳞片状薄片脱落.     

工艺参数对HVOF喷涂WC-Co涂层磨损性能的影响

采用滑动磨损试验机对不同工艺参数下HVOF喷涂WC-Co涂层进行滑动磨损试验,并分析了涂层的表面失效行为。氧气流量和燃气流量对涂层磨损性能的影响呈不同的变化规律,较小的氧气流量、适中的燃气流量和喷涂距离条件下制备的涂层磨损率较低。涂层滑动磨损失效具有解理断裂特征。失效过程中碳化物颗粒的剥落对涂层磨损起关键作用,涂层中的粘结相、孔隙对疲劳裂纹的扩展有很大的影响。     

激光熔覆WC/Ni基复合涂层高温滑动干摩擦磨损性能

利用激光熔覆技术制备微米团聚和块状两种不同类型WC/Ni基复合涂层。在MMG-10型摩擦磨损试验机上对涂层进行高温滑动干摩擦磨损实验,并用SEM和EDS对涂层进行磨损形貌观察和成分分析。结果表明,激光熔覆WC/Ni基复合涂层高温磨损性能随着WC含量增加而提高,WC形态为微米团聚质量分数为60%的复合涂层具有优良的高温耐磨性能。高温下60%WC/Ni基复合涂层主要磨损机制由低温下的磨料磨损转变为氧化磨损和磨料磨损复合作用。     

热处理对激光熔覆钛基复合涂层组织和微动磨损性能的影响

为研究不同温度热处理对激光熔覆钛基复合涂层组织和微动磨损性能的影响,采用激光熔覆技术在TA2钛合金表面制备40%Ti-25.2%TiC-34.8%WS_2(质量分数)复合涂层,将涂层分别置于300,500℃和700℃真空中保温1h,分析热处理前后涂层的显微组织和微动磨损耐磨性能。结果表明:未经过热处理涂层及经过不同温度热处理涂层的主要物相均为α-Ti,(Ti,W)C_(1-x),TiC,Ti_2SC和TiS。未热处理及经过300,500℃和700℃热处理1h涂层的显微硬度分别为1049.8,980.7,1143.3HV_(0.5)和1190.7HV_(0.5)。经过700℃热处理1h涂层表现出优异的微动磨损性能,磨损机理为黏着磨损和磨粒磨损。     

爆炸喷涂AlCuFeSc准晶涂层的摩擦学性能研究

采用爆炸喷涂制备了AlCuFeSc准晶涂层,借助扫描电镜、X射线衍射对准晶涂层的微观及物相结构进行了表征,通过显微硬度计测试了准晶涂层的表面硬度,结果表明涂层与基体间结合良好,其中涂层主要由准晶相和β-AlFe组成,室温下涂层的表面硬度为569.4HV0.3,经退火处理后涂层硬度最高可达到658.33HV0.3。同时开展了在室温和700 ℃高温环境中,5、15、25 N不同载荷下AlCuFeSc准晶涂层的摩擦磨损性能研究,利用白光干涉仪对磨痕进行三维形貌观测并计算磨损的磨痕宽度、磨痕深度、体积损失,得出磨损率;采用SEM分析了不同实验条件下磨痕形貌的特征。结果表明,AlCuFeSc准晶涂层在不同温度及不同载荷下的耐磨系数在0.500~0.656之间(均低于基体),室温环境下准晶涂层的磨损机制随载荷增加从磨粒磨损为主转变为粘着磨损为主;高温环境下磨损机制则都以粘着磨损为主,准晶涂层对2A12基体具有良好的减摩耐磨功能。     

钛表面激光熔覆原位制备Ti5Si3涂层结构及摩擦学性能

利用激光熔覆技术在钛表面预置硅粉原位制备了Ti5Si3涂层.用XRD、SEM和TEM分析了涂层的组成和组织结构.在UMT摩擦磨损试验机上对Ti5Si3涂层在不同载荷和不同滑动速度下的摩擦磨损性能进行了测试.实验结果表明:涂层的物相主要是Ti5Si3相和基材Ti相,涂层的显微结构为球状和块状晶,Ti5Si3涂层具有较高的显微硬度,涂层截面的平均显微硬度约为840 HV0.2,是钛基材的4.4倍;Ti5Si3涂层可显著提高钛基材的耐磨性能;Ti5Si3涂层的磨损机理为磨粒磨损和粘着磨损.     

超音速火焰喷涂Cr3C2-NiCr涂层腐蚀冲蚀磨损特性

在腐蚀冲蚀磨损试验机上,用5%H2SO4和质量分数15%棕刚玉组成的腐蚀-冲蚀磨损介质,对不同燃气流量下HVOF喷涂Cr3C2-25%NiCr涂层腐蚀冲蚀磨损性能进行了试验研究,测定了涂层单位面积失重量随腐蚀冲蚀磨损时间和冲蚀角度的变化,用扫描电镜观察了涂层断面组织形貌,分析了涂层腐蚀冲蚀磨损机制.研究表明,涂层的腐蚀...     

Effect of the particle size of nanosilica on the performance of epoxy/silica composite coatings

Four kinds of colloidal silica particles with different size (27, 58, 79 and 173 nm, respectively) were synthesized by sol-gel process and modified with 3-glycidoxypropyltrimethoxysilicane, then homogenously dispersed into the epoxy resin and cured with alicyclic amine on aluminum alloy substrates. The results showed that the Si-O-Al bond was formed at nanocomposite coat/substrate interface, introducing nanosilica significantly enhanced the adhesive strength, scratch resistance, abrasion resistance and corrosion resistance of coats, but different particle sizes of nanosilica had various impact on these properties, which seemed to be related to the structure of the silica surface.     

Pilot Study on the Nano-Composites Coats of Radar Wave''s Absorption

This thesis mainly introduced the guiding principle and physical model of the research on the nano-composites coats of radar wave's absorption, and then studied the qualitative analysis of the performance ameliorating of radar wave's absorption composite coats. And on the basis of the optimum design of multilayer wave's absorption materials, two new kinds of radar wave's absorption composite coats have been made, which are composed of nano-composites hydroxyl iron powder and hollow micro-sphere. The research indicated that the surface-density of these two new composite coats is less than 3.5 Kg/m2.The coats' thickness is about 1 mm. And the waves absorption capability is above the level of 5 db, in the range of 3 ～ 18GHz. Therefore the wave's absorption performance of these two new coats is better than nano-crystalloid in low frequency area. The pilot study has proved that the nano-composites coat's performance of radar wave's absorption excels the ordinary radar wave's absorption coats, so it needs to be further studied.     

镀液中SiC含量和粒径对Ni-P-SiC复合化学镀层性能的影响

采用化学镀方法制备了Ni P SiC复合镀层 ,系统研究了镀液中SiC含量和粒径对镀层结构及显微硬度的影响。结果表明 ,镀层中SiC析出量随镀液中SiC含量的增加而增加 ,在SiC含量一定的情况下 ,当SiC粒径为 7.0 μm时 ,析出量最大 ;镀液中SiC的含量和粒度对原始镀层的硬度影响不大 ,但对 4 0 0℃热处理后的镀层硬度有显著影响     

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.     

Study on the morphology and tribological properties of acrylic based polyurethane/fumed silica composite coatings

Two fumed silica (one hydrophilic and one hydrophobic) were used in the high solid acrylic based polyurethane coatings by directly mixing. The dispersion of fumed silica particles in the bulk of polyurethane coats was characterized by transmission electron microscope (TEM) and surface morphology examined using a scanning probe microscope (SPM). Micro indentation and scratching tests were carried out with a nano-indenter. Both hydrophilic and hydrophobic fumed silica nearly have the same dispersion in acrylic based polyurethane coats. The surface roughness of polyurethane coats increases as fumed silica increases, however, the surfaces of polyurethane coatings containing hydrophobic fumed silica are rougher than that containing hydrophilic fumed silica at the same content. Addition of fumed silica can obviously enhance the micro indentation hardness (MIH) and elastic modulus of polyurethane coats and the higher the content of fumed silica is, the higher the MIH is for hydrophilic one but for hydrophobic one only under normal load less than 20 mN. In the micro scratch experiment, the elastic response and plastic deformation nearly keep constant with normal force increasing for pure acrylic based polyurethane coats. But the percentage of elastic response decreases and the percentage of plastic deformation increases as normal force increases for the polyurethane coats with fumed silica. Crack occurs when scratching under normal force higher than 50 mN for the polyurethane coats with fumed silica, and as the content of fumed silica increases, the critical force for crack increases. Additionally, both hydrophilic and hydrophobic fumed silica have no obvious influence on the response to marring stress and micro mar resistance (MMR) of acrylic based polyurethane.     

苯乙烯-马来酸酐接枝预聚物对PS版光敏涂层性能的影响

讨论了３ 种苯乙烯马来酸酐预聚物的结构和用量对 Ｐ Ｓ 版光敏涂层性能的影响。结果得出, 在相同用量情况下,苯乙烯马来酸酐接枝 Ｐ Ｅ Ｔ Ａ 预聚物（ Ｓ Ｍ Ｐ） 对涂层感度、显影性等性能的影响最显著。     

电沉积锌基复合镀层的研究现状

综述了近几年国内外用电沉积方法制备锌基复合材料镀层的工艺及应用情况 ,对一元锌基复合镀层和二元锌基合金复合镀层的电镀工艺和特点作了较为详细的论述 ,并指出了尚存在的问题及今后的研究方向。     

金属喷涂长效复合防护涂层在海洋大气环境中的应用

通过对钢铁基底热喷涂锌、铝及锌铝合金复合有机涂层封闭防护体系在厦门海域进行的实海试验腐蚀状况分析 ,发现Zn Al合金涂层在海洋环境条件下的耐蚀性优于Al涂层及Zn涂层 ,在此基础上 ,提出了某大型工程项目适用的热喷涂长效复合防护涂层方案。     

Study on mechanical properties of high-temperature absorbing coats

SiCN nano-powder, a good high-temperature absorber, was introduced as the absorber into the BaO–La₂O₃–B₂O₃ glass to prepare the high-temperature absorbing coats on the Ti-based alloy substrates. The difference of thermal expansion coefficient between the glass and Ti-alloy was determined through thermal mechanical analysis (TMA) and the wet ability of the glass to the substrate was explored. The mechanical properties including the tensile strength and the resistance to thermal shock of the coats were investigated, and the effects of coating temperature and absorber content on the properties of coats were discussed. Results show that it is feasible to prepare the absorbing coat using the BLB glass as the binder. The BLB glass possesses good tensile strength and the introduction of the SiCN absorber into the glass coat will lower the tensile strength. With the increase of SiCN content, the tensile strength of the absorbing coat becomes worse, which could be attributed to the aggregate of SiCN in the coats. As the SiCN content increases, the resistance to thermal shock of the coats shows the tendency that increases firstly and then decreases. The glass coat containing the SiCN absorber possesses the better resistance to thermal fatigue than the glass coat without SiCN, indicating that the introduction of SiCN absorber in the glass could improve the thermal resistance of the coat.