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。     

不同基体前处理对AlCrN涂层结构和性能的影响

目的 通过对基体进行前处理,提高AlCrN涂层的摩擦磨损性能和切削性能.方法 采用不同前处理方法(湿喷砂、干喷砂和微粒子喷丸)对高速钢基体表面进行处理,随后沉积AlCrN涂层,利用X射线衍射以、扫描电子显微镜等仪器,以及切削试验,分析不同前处理方式对涂层组织结构、膜基结合力、表面形貌、表面粗糙度、摩擦磨损性能以及切削性...     

表面处理对AZ91D电弧喷涂铝层性能的影响

分别采用表面腐蚀和表面喷砂对AZ91D进行表面处理,然后进行电弧喷涂工业纯铝,对比考察两种表面处理方法对涂层与基体的结合力和涂层的耐蚀性的影响.SEM分析表明,采用表面腐蚀方法处理的试样,其喷涂层锚固作用明显比表面喷砂试样强.拉伸和盐雾试验表明,采用表面腐蚀和表面喷砂处理的试样其涂层结合强度和腐蚀速率分别为:2.3750MPa、0.571×10-3g/(cm2·h)和1.7675MPa、1.057×10-3g/(cm2·h),表明在电弧喷涂工艺中,采用表面腐蚀处理方法明显优于表面喷砂.     

PVD涂层工业化应用及发展现状

结合PVD涂层技术的特点和发展现状,简述了各种表面处理方法的工作原理及其在PVD涂层工业制备过程中的应用。PVD涂层工业制备过程中涉及的表面处理方法主要包括:超声清洗、去毛刺、喷砂、钝化、抛光、脱气及退涂等。结合各种表面处理方法的特点及使用效果,对不同工作条件的待镀产品制定相对应的前、后处理工艺,确保涂层产品质量,大幅提升其工作寿命。     

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。     

前处理工艺对NdFeB表面真空蒸镀Al薄膜结构及性能的影响

为了开发烧结钕铁硼磁体表面低损伤、环境友好型镀膜前处理工艺,在分别采用抛光、酸洗(50 s)、吹砂、吹砂+酸洗(5 s)4种不同工艺处理的烧结NdFeB磁体表面真空蒸镀Al薄膜。经不同工艺前处理的NdFeB基体和涂层的形貌采用扫描电子显微镜进行观察;采用拉伸试验对Al涂层和基体之间的结合力进行测试;NdFeB基体的自腐蚀行为采用电化学极化曲线进行表征。结果表明:吹砂前处理后NdFeB基体表面存在一层晶粒损伤层,导致镀Al薄膜试样镀层与基体之间的结合力(9.54 MPa)最差。而采用吹砂+酸洗(5 s)前处理后NdFeB表面镀Al试样镀层与基体之间结合力可达13.58 MPa。酸洗(50 s)及喷砂+酸洗(5 s)前处理后基体试样的自腐蚀电流密度基本相同(21μA·cm~(-2)),仅为抛光及喷砂前处理基体试样的20%。在4种工艺当中,吹砂+酸洗(5 s)前处理工艺获得最高的结合力和优异的耐腐蚀性能。     

钛基体表面处理对无氰电刷镀银结合力的影响

采用无氰电刷镀银溶液，通过对钛基体进行喷砂、机械打磨、化学刻蚀等表面处理，电镀前再经过表面活化，可有效地提高钛基体与镀银层之间的结合力。     

提高清理效率降低清理成本

喷丸清理已成为钢材表面喷漆或热喷涂前的标准前处理方法。与手工清理和动力工具清理相比,具有清理效率高、清理质量好的优点;与抛丸清理相比,具有投资省、占地少、上马快、机动性和适应性强、操作和维修简单的特点;与酸洗相比,具有环境污染程度小且容易控制、被喷涂件的材质不受影响的优点。被喷丸件具有较大的表面粗糙度,有利于提高涂层的附着力。因此,喷丸清理已在造船、修船、集装箱、重型机械、钢结构行业得到普遍应用。与此同时,对喷砂设备及其系统提出了新的要求:     

热喷涂Ni基复合涂层重熔处理的研究现状

热喷涂Ni基复合涂层因具有耐磨、耐腐蚀及耐高温等特点,被广泛应用于机械零件的表面修复和保护。但是,热喷涂层为典型的层状结构,具有微缺陷含量较高、与基体结合强度低等特点,难以适应苛刻的工作环境,其应用和发展受限。重熔处理可以消除热喷涂层的层状结构,消除或部分消除孔隙、裂纹等微缺陷,使涂层与基体形成冶金结合,提高涂层的使用性能。本文首先介绍了几种适用Ni基复合涂层的重熔技术(即激光重熔、火焰重熔、感应重熔等),随后介绍了重熔处理对Ni基复合涂层表面完整性(即微缺陷、结合强度和硬度)的影响,接着分析了重熔处理对Ni基复合涂层两种服役性能(即耐磨性、耐腐蚀性能)的影响,最后总结了目前在关于Ni基复合涂层重熔技术研究中存在的问题,进而探讨了相应的解决方案,并指出挖掘新的表面重熔技术和对不同的材料体系进行针对性研究是未来重点发展的方向。     

Laser texturing as an alternative to grit blasting for improved coating adhesion on AZ91D magnesium alloy

Substrate preparation plays an important role in the performance of thermal spray coating, especially on softer materials like magnesium and aluminium alloys. Conventional substrate preparation methods such as grit blasting may not be the most suitable choice due to grit embedding, lower coating adhesion strength and environmental concerns. Laser texturing can be an attractive alternative to the grit blasting method for such materials. AZ91D substrate was prepared for thermal spray coating using grit blasting and laser texturing techniques. WC-12Co powder was thermally sprayed on AZ91D magnesium alloy using the high-velocity oxygen fuel technique. The adhesion strength of the coating, thus produced, was determined using the ASTM 633C adhesion strength test. Scanning electron microscopy was used to investigate substrate morphology and to qualitatively analyse substrate and coating interface. X-ray diffraction was used to identify phase compositions. The coating was characterised for roughness, porosity, micro-hardness and fracture toughness. Laser texturing as a substrate preparation technique has been able to produce well-adhered coatings, with adhesion strength of 45.6?MPa, and comparable coating characteristics with those of the grit blasting technique.     

Deposition and characterization of flame-sprayed aluminum on cured glass and basalt fiber-reinforced epoxy tubes

An oxy-acetylene flame spray torch was used to deposit thin layers of aluminum onto cured glass and basalt fiber-reinforced epoxy tubes. The composite specimens were fabricated by filament winding. Surface coatings embedded in composite laminates were produced. The composite substrates were grit blasted to promote adhesion of the molten aluminum particles. It was found that adhesion increased significantly when the composite substrate was lightly grit blasted, with no adhesion on smooth composite surfaces. The number of passes of the flame spray torch was varied to change the coating thickness and uniformity over the substrate. The electrical resistance of the coatings was measured to assess the suitability of a coating as a conductor. It was found that uniform, electrically conductive coatings were produced with a minimum of two torch passes. Optical images were captured to characterize the coating microstructure and thickness. This investigation did not reveal any visible evidence of damage to the composite substrate. To assess possible degradation effects from the grit blasting and flame spraying processes, the tube specimens were subjected to mechanical testing by applying internal pressurization with hydraulic oil. The tests indicated that the grit blasting and flame spraying processes must be carefully executed to mitigate degradation of the strength of the composite material substrate.     

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。     

Fatigue behavior of a SAE 1045 steel coated with Colmonoy 88 alloy deposited by HVOF thermal spray

An investigation has been conducted in order to study the fatigue behavior of a SAE 1045 steel substrate coated with a Ni-base alloy known commercially as Colmonoy 88, deposited by HVOF spray technique. Fatigue tests were conducted under axial conditions (R = 0.1), employing samples of the substrate material in the as-polished condition, after grit blasting with alumina particles and after grit blasting and coating with a deposit of about 250 μm thick. The fatigue tests were conducted at maximum stresses in the range of 380-533 MPa, depending on the condition of the material. A detailed fractographic analysis of some selected samples tested at different stresses was carried out, aimed mainly at determining the crack nucleation and propagation sequence. The results indicate that the deposition of such a coating leads to a fatigue strength debit of the substrate in the range of 10-20% and a similar debit in fatigue limit of ∼ 11-13%. It has been found that grit blasting is the process responsible for the fatigue strength debit observed in the coated samples. Fatigue cracks have been observed to initiate at the substrate-coating interface and at the free surface of the coating, mainly close to alumina particles embedded on the substrate and sharp notches produced during the process. The fractographic analysis of the fracture surface of the coated specimens points out the characteristic heterogeneous nature of the coating, particularly regarding some of its mechanical properties, such as fracture toughness.     

HVOF碳化钨金属陶瓷涂层对基体疲劳性能影响的研究现状

由超音速火焰喷涂（HVOF）制备的碳化钨金属陶瓷涂层,具有接近完全致密、结合强度高、硬度高等优势。本文综述了金属表面HVOF碳化钨金属陶瓷涂层疲劳寿命影响的研究现状,并分析了产生疲劳裂纹的原因,影响疲劳寿命的原因有涂层与基体的性能差异、喷砂引入的缺陷、残余应力及涂层制备工艺等的影响。改进措施有涂层设计、基体不做喷砂或喷丸替代喷砂等改变前处理工艺、获得或提高涂层压应力、减少碳化物的分解、合理的工艺参数（如高的速度）、合适的涂层厚度、选用高含量粘结物的碳化钨金属陶瓷粉末、合适的涂层后处理方法等措施。     

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.     

喷砂预处理对HVOF喷涂TiAl-Nb/NiCrAl涂层结合强度的影响

采用不同的喷砂压力对基体表面进行喷砂预处理,研究了基体表面状态的变化对HVOF喷涂TiAl-Nb/NiCrAl涂层结合强度的影响。结果表明：随着喷砂压力的增大,基体粗糙度及表面凹坑的深度和宽度增大,NiCrAl层与基体结合界面处孔洞等缺陷增多,同时基体表面残余砂粒的面积分数增加;涂层结合强度随基体粗糙度的增大,先增大后减小,当基体粗糙度为8.33μm时,结合强度达到最大值44.5 MPa。     

Residual stress development in cold sprayed Al,Cu and Ti coatings

Residual stresses play an important role in the formation and performance of thermal spray coatings. A curvature-based approach where the substrate–coating system deflection and temperature are monitored throughout the coating deposition process was used to determine residual stress formation during cold spray deposition of Al, Cu and Ti coatings. The effect of substrate material (carbon steel, stainless steel and aluminium) and substrate pre-treatment (normal grit blasting, grit blasting with the cold spray system and grinding for carbon steel substrate) were studied for all coating materials with optimized deposition parameters. Mainly compressive stresses were expected because of the nature of cold spraying, but also neutral as well as tensile stresses were formed for studied coatings. The magnitudes of the residual stresses were mainly dependent on the substrate/coating material combination, but the surface preparation was also found to have an effect on the final stress stage of the coating.     

微粒轰击Fe基非晶电弧喷涂层性能强化

为了减小热喷涂层残余应力对涂层质量的不利影响,采用喷丸(砂)微粒轰击与高速电弧喷涂相互循环交替的工艺制备了Fe基非晶涂层,使涂层残余拉应力变为残余压应力,喷丸(砂)强化涂层表面残余应力由未处理涂层表面残余拉应力277 MPa分别变为残余压应力-177 MPa(-91 MPa)。利用电子扫描显微镜、纳米压痕仪、摩擦磨损试验机等分别对涂层的微观形貌、力学性能和摩擦磨损性能进行了测试。结果表明:经过微粒轰击后的涂层表面致密平整,组织结构密实,喷丸(砂)强化涂层的孔隙率仅为1.0%(1.5%),结合强度可达44.6 MPa(56.4 MPa),经过微粒轰击后涂层硬度、弹性模量及摩擦磨损性能都有所提升。喷丸强化涂层局部过度的轰击会使涂层结合强度及摩擦磨损性能略有下降。     

Influence of Grit Blasting on the Roughness and the Bond Strength of Detonation Sprayed Coating

The process of roughening the surfaces by grit blasting prior to coating them using thermal spray techniques is very important to obtain consistently high tensile bond strength between the coating and the substrate. The available literature on the influence of grit-blasting parameters in the case of detonation spray or HVOF coatings is quite limited. The present study aims to study the influence of grit-blasting pressure and alumina grit size on the roughening of the mild steel substrate, the resulting effect on the roughness of Cu, Al₂O₃, and WC-12Co coatings deposited by detonation spray coating and also on the tensile bond strengths of these coatings. Toward the above purpose, the velocity of the alumina grits have been experimentally measured using a high-speed imaging system and the tensile bond strength of the coatings have been experimentally obtained using the pin type test. The results from the above experiments point to the importance of not only the roughness of the grit-blasted mild steel substrate but also the roughness of the coatings subsequently deposited in determining the magnitude of the bond strength.