基体表面粗糙度对涂层结合强度的影响

采用不同粒度的喷砂材料对基体表面进行喷砂粗化预处理,研究基体表面粗糙度的变化及其对等离子涂层和电弧涂层结合强度的影响.结果发现,基体表面粗糙程度对涂层与基体的结合强度有很大的影响.对于等离子喷涂,表面粗糙度应该存在一个最佳范围,并不是表面粗糙度越大,涂层与基体的结合就越好.喷涂方法不同,粗糙度的变化对涂层结合强度的影响不同.     

热喷涂铝过渡层对FEP涂层与钢基体结合强度的影响

研究了喷砂工艺和热喷涂铝过渡层对聚全氟乙丙烯(fluoroethylenepropylene,FEP)涂层与钢基体结合强度的影响.结果表明,喷砂处理后,涂层和基体结合强度随基体表面粗糙度增加先增后降.采用热喷涂工艺在钢基体上制备了铝过渡层,用扫描电镜和表面粗糙度测量仪研究了喷砂以及铝过渡层的表面形貌和表面粗糙度,用拉开法测定了FEP涂层和钢基体的结合强度.铝过渡层具有粗糙多孔的表面结构,在一定程度上增进了 FEP涂层与基体的结合强度.     

表面机械处理对5×××铝合金/涂层体系的结合强度和晶间腐蚀性能的影响

采用金相显微镜、电化学交流阻抗和扫描电镜研究表面机械处理(喷砂和打磨)对5×××铝合金/涂层体系的结合强度及晶间腐蚀性能的影响。结果表明:试样经表面机械处理后,基体表面的清洁度提高,粗糙度增大,涂层与基体的结合强度显著提高;其中表面喷砂后,基体与涂层结合强度提高198.7%;表面打磨后,基体与涂层结合强度提高167.4%;表面机械处理后,基体的耐晶间腐蚀能力明显降低,但合金/涂层体系的耐晶间腐蚀能力显著提高;表面喷砂后,合金/涂层体系与基体的耐蚀性都强于表面打磨后的耐蚀性。     

喷砂表面三维粗糙度参数对涂层结合强度的影响

目的揭示喷砂预处理表面三维粗糙度参数对热喷涂层结合强度的影响规律。方法以喷砂距离和喷砂速度为影响因子,对45#钢试样进行喷砂处理,采用三维光学显微镜测得各工艺参数下喷砂表面的三维形貌及三维粗糙度参数,并利用"粘接-拉伸"测试方法测得涂层的结合强度。利用回归分析方法,建立涂层结合强度与三维粗糙度参数间回归数学模型,并进一步分析三维粗糙度参数的影响机制。结果喷砂预处理表面随机分布着许多不规则形状的凸峰和凹坑,方向各异,没有固定的取向,其整体表面粗糙度S_a平均为4.84μm,涂层结合强度平均为32.8 MPa。涂层结合强度与三维粗糙度参数间存在着非线性相关关系,且S_a、S_(dr)、S_(dq)、S_q对涂层结合强度的影响较为显著。S_a和S_(dr)越大,有利于增大涂层与基体的接触面积;S_(dq)较大时,所形成的凹坑及凸峰较为尖锐,有利于为涂层机械结合提供更多的锚固点;结合界面的S_q较大时,其表面形貌以较深的凹坑为主,导致凹坑深处易形成残留气孔缺陷,降低涂层与基体间的润湿效果及结合性能。结论 S_a、S_(dr)、S_(dq)、S_q为涂层结合强度的主要影响因素,且存在非线性回归关系,各三维粗糙度参数对涂层结合强度的影响机制及趋势与回归数学模型一致。     

喷砂工艺对钛阳极表面形貌、电催化活性和寿命的影响

通过扫描电镜、X射线衍射、阳极极化曲线和加速寿命等试验研究基体喷砂预处理对Ti/IrO2·Ta2O5阳极的表面形貌、析氧电催化活性和寿命的影响。结果表明:钛阳极表面形貌受喷砂工艺压力和磨料粒度的影响,喷砂压力对钛基体的粗糙度Ra贡献大,在磨料粒度相同的情况下,粗糙度近似与压力成正比;基体的粗糙度Ra的不同影响涂层的表面形貌和晶粒尺寸,随着Ra增大,涂层中活性组元IrO2的晶粒得以细化;基体的粗糙度Ra值对晶粒形核生长、阳极的电催化活性和寿命的影响是重要的,但并非Ra越大,晶粒析出越多,直接的影响因素是基体表面微观凸起的数量;表面微观凸起的数量影响到阳极的电催化活性,IrO2晶化的量越多,析氧电流就越大;基体的粗糙度Ra并非与钛阳极的寿命成正比;基体的粗糙度Ra为3.6μm的阳极析氧催化活性和寿命分别提高7%～36%和63%～72%,兼具最佳的析氧催化活性和最长的寿命。     

表面预处理对PPS/FEP复合防腐涂层结合强度的影响

采用拉开法测定了砂纸打磨、酸洗、磷化以及喷砂等多种表面处理条件下PPS／FEP复合防腐涂层的结合强度，用扫描电镜(SEM)和表面粗糙度测试仪分析了试样经各种表面处理后的表面形貌及粗糙度。结果表明，磷化处理后试样表面具有均匀致密的显微孔隙结构，涂层结合强度最好；喷砂处理的效果仅次于磷化；砂纸打磨条件下，随表面粗化程度的增加，结合强度增加；酸洗后表面粗糙度较低，因而涂层结合强度低，但比同等粗糙度的砂纸打磨效果好。     

不同硬度基体下等离子喷涂钼合金涂层结合性能

采用相同的等离子喷涂工艺,对基体60钢的调质状态和高频淬火状态两种表面进行喷涂Mo合金粉末试验;通过拉伸试验测定了涂层的强度,采用金相显微镜和扫描电镜观察了涂层的微观形貌。结果表明:两种状态下的表面均可获得以高熔点的钼为软基体、镍基合金作为硬骨架的等离子涂层;调质状态下所获涂层的结合强度稍高于高频淬火状态下所获涂层的结合强度。基体处于调质状态时,表面喷砂粗化后粗糙度较大,与涂层的机械咬合效应要好于高频淬火状态。在高频淬火状态下,涂层内部的残余应力对涂层的内聚强度有较大的削弱。     

钛基体上IrO2+MnO2涂层的表面形貌和电催化活性

对表面粗糙度不同的钛(Ti)基体进行抛光和喷砂处理,通过H2IrC16和Mn(NO3)2水溶剂在处理后的基体上制备IrO2+ MnO2涂层.采用扫描电子显微镜(SEM),场发射扫描电子显微镜(FESEM),循环伏安法(CV)和阳极极化曲线研究了不同表面粗糙度的IrO2+MnO2涂层的表面特性,结构和电催化活性.在所有通过喷砂处理的基体表面上制备的IrO2+MnO2涂层中,都可以分离出二氧化铱纳米棒,但通过抛光处理的涂层不能形成.通过喷砂处理的IrO2+MnO2涂层的qT,q.,qi和i/qT值远远高于抛光处理的涂层.表面粗糙度为1.3 μm的IrO2+MnO2涂层比其他涂层具有更好的电催化活性.     

钛基体上IrO_2+MnO_2涂层的表面形貌和电催化活性（英文）

对表面粗糙度不同的钛(Ti)基体进行抛光和喷砂处理,通过H2IrCl6和Mn(NO3)2水溶剂在处理后的基体上制备IrO2+MnO2涂层。采用扫描电子显微镜(SEM),场发射扫描电子显微镜(FESEM),循环伏安法(CV)和阳极极化曲线研究了不同表面粗糙度的IrO2+MnO2涂层的表面特性,结构和电催化活性。在所有通过喷砂处理的基体表面上制备的IrO2+MnO2涂层中,都可以分离出二氧化铱纳米棒,但通过抛光处理的涂层不能形成。通过喷砂处理的IrO2+MnO2涂层的qT,qo,qi和i/qT值远远高于抛光处理的涂层。表面粗糙度为1.3μm的IrO2+MnO2涂层比其他涂层具有更好的电催化活性。     

结晶器铜板超音速火焰喷涂工艺参数对涂层结合强度的影响

文中采用超音速火焰喷涂（HVOF）在结晶器铜板表面喷涂了CoNiCrAlY涂层,研究了喷涂主要工艺参数对涂层结合强度的影响。结果表明：涂层的结合强度随着燃油流量的增大而显著增大,随着氧气流量与喷涂距离的增加结合强度均出现先增加后下降趋势,喷砂后较未喷砂结合强度大大提高。选择合适的粉末形状与粒径对于获得高质量的涂层较为重要。     

Effects of plasma-sprayed NiCrAl/ZrO2 intermediate on the combination ability of coatings

A NiCrAl/ZrO₂ composite coating was deposited on the surface of metal carrier FeCrAl alloy by a plasma-spray technique. After static-state oxidation at 800°C, the transitions in structure and composition of the coating was analyzed by XRD, SEM and EDX. The results showed that the surface phases of the as-sprayed coating were mainly composed of Ni and ZrO₂. When the oxidation time was extended from 8 to 50 h, NiO crystallites were formed and these grew coarse on the coating surface, and alloy elements were diffused between the NiCrAl/ZrO₂ coating and the FeCrAl substrate. With the pretreatment, an intermediate coating was prepared with a coarse and porous structure, high cohesive strength and high heat resistance. These developed properties could provide high geometric surface area for a catalytic γ-Al₂O₃ washcoat, and enhance the adhesive strength between ceramic washcoat and metal substrate so as to extend the lifetime of the washcoat.     

等离子喷涂WC-12Co/NiCrAl复合涂层的摩擦磨损特性

以NiCrAl涂层为粘结层,用等离子喷涂工艺在TC4钛合金表面制备了WC-12Co/NiCrAl复合涂层。通过扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和显微硬度仪等手段分析了涂层微观形貌、化学成分和显微硬度,并用磨损试验考察了WC-12Co/NiCrAl复合涂层的摩擦磨损特性。结果表明:WC-12Co涂层表面未熔颗粒较多,涂层截面孔隙率为10.2%;WC发生部分分解,出现W2C、Co6W6C等新相;涂层与基体结合界面为机械结合+局部微冶金结合方式;显微硬度为双态Weibull分布,呈现不同位置结构的差异化。WC-12Co涂层表现出良好的减摩及耐磨性能,同载荷下摩擦因数低于基体,磨损失重为基体的1/10,磨粒磨损是其主要磨损机制。     

Combination Effect of Dry-Ice Blasting and Substrate Preheating on Plasma-Sprayed CoNiCrAlY Splats

CoNiCrAlY splats were plasma-sprayed on the stainless steel substrate which was pretreated by dry-ice blasting. Only impact marks were distinguished on the glycerol-polluted substrate, while halo donut splats formed on the pretreated substrate because of the cleaning effect of dry-ice blasting on this organic substance. The proportions of different splat types vary as a function of the treatment time of dry-ice blasting. The condensation phenomenon was also detected on the substrate surface accompanying the cleaning effect after the pretreatment of dry-ice blasting. In this study, dry-ice blasting was investigated to be coupled with substrate preheating to control the substrate temperature. It was found that a regular disk-like CoNiCrAlY splat can be obtained as the substrate temperature is higher than dew point temperature.     

陶瓷/金属复合耐磨涂层的微观结构与磨损性能分析

采用大气等离子喷涂技术在铸铁基体表面制备WC／NiCrAl和WC／NiCrBSi涂层试样，并从微观结构、显微硬度和磨损性能等方面测试涂层性能。结果显示，在磨损性能方面，以NiCrBSi为粘结金属的涂层优于以NiCrAl为粘结金属的涂层；WC含量高的涂层优于WC含量低的涂层。并探讨了涂层的磨损机理和磨损性能的变化规律，从而为耐磨涂层的设计提供指导。     

Peening Effect of Thermal Spray Coating Process

The present study investigated the influence of grit blasting, feedstock powder, and thermal spraying technology on performance near the surface on the substrate’s side. The experimental results show that both the grit-blasting process and thermal spraying process harden the substrate, and microhardness on or near the surface was noticeably increased. Grit blasting created deformed regions next to the surface of the substrate and interface between entrapped grits and substrate. Initial equiaxed grains in the deformed regions were elongated and spirally oriented surrounding impact spots. There were no visible changes in microstructure caused by thermal spraying, and the elongated grain regions remained in the coated substrate. Substrate hardening was attributed to grit blasting and associated heating due to flame rather than powder particle impacting during thermal spraying, thus feedstock powder and individual thermal spray technology had no influence on the hardening.     

干冰微粒喷射工艺对等离子喷涂金属涂层结构和性能的影响

干冰微粒喷射法被应用到大气等离子喷涂中以改善涂层的性能。文中采用等离子喷涂和干冰微粒喷射工艺在不锈钢基体表面制备了钢涂层,并研究了涂层的微观结构、孔隙率、温度、氧化、表面粗糙度和结合强度等性能。结果表明,由于干冰微粒喷射具有较高的冷却效率,加之干冰微粒撞击所产生的机械作用,等离子喷涂制备的钢涂层呈现出更致密的结构特征。相比于空气冷却制备的涂层,干冰微粒冷却制备的涂层含有更少的氧化物。另外,干冰微粒喷射工艺对基体的预处理使得涂层的结合强度提高了将近14%,这是由于干冰微粒喷射工艺对基体上吸附的有机物质具有清洁作用,主要基于干冰颗粒的热、机械和膨胀的综合效应。     

Alumina grit blasting parameters for surface preparation in the plasma spraying operation

This paper examines how the grit blasting process influences the surface roughness of different sub-strates, the grit residue, and the grit erosion. The influence of grit blasting conditions on induced sub-strate residual stresses is also discussed. Aluminum alloy, cast iron, and hard steel were blasted with white alumina grits of 0.5,1, and 1.4 mm mean diameters. Grit blasting was performed using either a suction-type or a pressure-type machine equipped with straight nozzles made of B4C. The influence of the follow-ing parameters was studied: grit blasting distance (56 to 200 mm), blasting time (3 to 30 s), angle between nozzle and blasted surface (30°, 60°, 90°), and blasting pressure (0.2 to 0.7 MPa). The roughness of the substrate was characterized either by using a perthometer or by image analysis. The grit residue remain-ing at the blasted surface was evaluated after cleaning by image analysis. The residual stresses induced by grit blasting were determined by using the incremental hole drilling method and by measuring the de-flection of grit-blasted beams. Grit size was determined to be the most important influence on roughness. The average values of R_a and Rt and the percentage of grit residue increased with grit size as well as the depth of the plastic zone under the substrate. An increase of the pressure slightly increased the values of Ä_a and Rt but also promoted grit breakdown and grit residue. A blasting time of 3 to 6 s was sufficient to obtain the highest roughness and limit the grit breakdown. The residual stresses generated under the blasted surface were compressive, and the depth of the affected zone depended on the grit diameter, the blasting pressure, and the Young’s modulus of the substrate. More-over, the maximum residual stress was reached at the limit of the plastic zone (i.e., several tenths of a mil-limeter below the substrate surface).     

预处理对压铸镁合金微弧氧化膜的影响

微弧氧化前,用打磨和喷砂两种方法对基材进行预处理,获得两种氧化膜试样,对比了这两种试样的形貌、化学组成及耐腐蚀性能,分析了预处理方法对微弧氧化电压值的影响。结果表明:打磨后微弧氧化的电压值高于喷砂后微弧氧化;微弧氧化膜的耐蚀性能较基体大幅度提高,打磨试样的耐蚀性能较喷砂试样提高了40%左右;喷砂试样的氧化膜表面整体保留了喷砂后粗糙不平的形貌,而打磨试样的氧化膜较喷砂试样平整,微孔尺寸均匀且较喷砂试样的尺寸小;氧化膜表面的化学成分主要有O,Mg,Si,Al等,预处理对氧化膜化学成分及含量的影响不显著。     

Examination of a grit-blasting process for thermal spraying using statistical methods

An experimental study was conducted to develop an understanding of how the grit blasting process, prior to plasma spray coating, affects various properties of the substrate and coatings. A statistical design of experiment approach was used and the results were analyzed using both the linear regression method and average response of factors calculations. The following process variables were studied: grit size (20, 36, 54), blasting pressure (20, 35, 50 psi), blasting duration (4, 6, 8 passes), blasting distance (4, 6 in.), and blasting angle (45°, 90°). Properties such as bond strength, grit contamination, surface roughness, and substrate distortion were evaluated and correlated to the process variables. Based on multiple linear regression results, it was shown that the bond strength can be improved by increasing all of the parameters within the range studied here. No relationship between the surface roughness and bond strength was observed. Grit contamination is mostly influenced by grit size, blasting pressure, and number of blasting passes. The average response method provided indications to the direction of modifying the required properties as a function of process variables. While the average response method agreed mostly with the linear regression predication, some differences are further discussed in the study.     

Thermal Performance and Microstructure of Vacuum Plasma Sprayed Tungsten Coatings under Cyclic Heat Load

采用真空等离子喷涂技术在铜基体表面制备了钨涂层,分别通过NiCrAl和W75Cu25涂层作为中间层。5 MW/m2, 2 s的高热负荷电子束实验表明NiCrAl中间层提高了涂层的热导率并降低了热应力和残余应力值。W75Cu25涂层作为中间层则表现出较差的热疲劳性能。高热负荷电子束真空等离子喷涂钨涂层表现出侵蚀和微裂纹。因热应力导致涂层发生塑性变形,在高温情况下裂纹起源于熔融的钨颗粒,但是,裂纹被钨涂层塑性变形和孔洞所抑制