Study of Corrosion Behavior of Arc Sprayed Aluminum Coating on Mild Steel

In the current study, aluminum coating was deposited on mild steel by arc spraying. A well-adhered coating with low level of porosity was successfully obtained. To evaluate the corrosion behavior of the coating, electrochemical impedance spectroscopy (EIS) and polarization tests in 3.5% NaCl solution were carried out. The as-coated samples were also subjected to a 1500-h salt spray assay. Polarization tests indicated that the corrosion current density of the aluminum coating is more than that of bulk aluminum. This could be due to the penetration of the electrolyte through open pores, resulted in the acceleration of aluminum corrosion. EIS measurements showed that the corrosion performance of the coating is improved during a long time immersion and exposure to saline mist. This could be due to plugging of pores by corrosion products which hinder further penetration of the electrolyte through the coating. The results obtained indicated that twin wire arc sprayed aluminum coatings can reliably protect steel structures against corrosion in chloride-containing aqueous solutions.     

火焰喷涂碳化物涂层的耐磨性研究

对碳化物复合粉末热喷涂工艺和Ni基自熔合金粉末热喷焊工艺进行了研究，在低碳钢基体上分别采用氧-乙炔火焰喷涂Co包WC粉末、Ni包WC粉末，以及火焰喷焊Ni60、Ni60 20％WC自熔合金工艺获得耐磨合金涂层。研究了涂层的显微结构和相特征以及耐磨性。结果表明，在喷焊Ni60 20％WC粉末涂层的组织中，由于加入了WC粒子，有效改善了涂层的显微组织和性能，得到了喷焊质量和耐磨性俱佳的合金涂层。     

盐雾环境下X70管线钢等离子喷涂铝涂层的腐蚀行为

目的研究X70管线钢的防腐工艺,以延长其使用寿命。方法采用等离子喷涂方法在X70管线钢基体表面制备铝涂层,通过扫描电镜(SEM)和能谱仪(EDS)对涂层表面、界面质量和微观形貌进行分析。利用盐雾腐蚀试验,对比分析涂层对基体的保护作用机制。结果涂层为富铝层,主要以富铝脆性物相存在,并受环境空气的影响,涂层出现孔洞、裂纹和未熔颗粒等缺陷。涂层表面因铝粉颗粒尺寸差异,颗粒间熔融状态不同,导致表面铝元素呈波浪式分布。涂层界面结合处,铁、铝元素相互渗透,形成Fe-Al冶金结合,增加了涂层结合强度。热处理后,未熔颗粒及部分金属氧化物熔化并填充涂层缺陷,减小了表面粗糙度和孔洞率,提高了涂层质量。盐雾腐蚀16h后,未喷涂涂层试样表面出现了严重的点蚀现象,影响了管线钢的使用寿命。喷涂铝涂层试样在盐雾腐蚀试验120h后,表面出现了轻微腐蚀现象。结论涂层表面形成了致密氧化膜,避免了腐蚀介质和基体直接接触,提高了X70管线钢的耐腐蚀性。     

碳钢的渗钛模型

本文从Fick第二扩散定律出发,建立了适用于气体或固体渗钛的数学模型,并通过碳钢的固体渗钛实验进行验证。结果表明,该数学模型与实验结果拟合性好,能用来描述碳钢的渗钛过程。     

不锈钢表面等离子喷涂梯度涂层耐蚀性能的研究

利用等离子喷涂技术在不锈钢表面喷涂由底层（NiCrAlY）和面层（ZrO2＋Y2O3）组成的梯度涂层。用SEM和XRD方法表征了梯度涂层的显微组织和相结构;用显微硬度仪测量涂层的显微硬度;采用CS300P型电化学腐蚀工作站检测了梯度涂层的耐蚀性能。结果表明,在不锈钢表面等离子喷涂NiCrAlY＋（ZrO2＋Y2O3）梯度涂层的厚度约为300μm,相成分主要是ZrO2和Ni3Al,显微硬度值达到1000HV;在1．0mol／L的稀硫酸腐蚀液中,喷涂后的试样表面腐蚀速率显著减慢,耐蚀性能得到明显提高。     

Flame Sprayed Al-12Si Coatings for the Improvement of the Adhesion of Composite Casting Profiles

In this study, flame sprayed Al-12Si coatings were produced on the surface of inlays (aluminum profiles) of composite castings parts. The aim was to enhance the strength between the joining partners inlay and cast. Due to the high surface roughness and the presence of pores in the coatings, combined with the formation of an intermetallic phase at the interface, the adhesion of flame sprayed inlays could be enhanced by a factor of 2 compared to blank inlays and by a factor of 1.3 when compared to sand-blasted inlays. However, results also show that gaps are present, mostly at the interface between the inlays and the flame sprayed coatings, and these gaps have a negative effect on the joining strength of the composite casting parts. Therefore, optimizing the adhesion of the coating on the Al profiles via an improvement in both the sand-blasting and the flame spraying parameters would be beneficial for further enhancement of the adhesion of composite casting parts.     

Q235钢表面纳米陶瓷涂层性能的研究进展

综述了近年来Q235钢表面制备纳米陶瓷涂层的研究进展,介绍了热喷涂法、熔敷法、热化学反应法、多元复合化学镀等技术的研究成果,分析了各种制备技术的优缺点,并展望了今后Q235钢表面制备纳米陶瓷涂层的发展方向.     

钢管表面结构对热喷玻璃涂层的影响

研究了钢管经酸洗和喷砂除锈后表面结构对热喷玻璃涂层的影响,结果表明：金属／瓷层界面发生了一系列复杂的物理化学反应,铁、镍元素在界面发生富集、形成过渡层,使瓷层与金属密着良好,表面层相结构主要为玻璃态,有少量Ｎａ２ＭｏＯ４（ＭｏＯ３）ｙ晶相存在,热喷玻璃涂层表面光滑、无裂纹、酸洗表面喷瓷后,瓷层中产生大量气孔,金属／瓷层界面产生大量微裂纹。     

建筑用Q235钢的表面镀层与耐腐蚀性能研究

采用热浸镀方法在建筑用Q235钢面制备了55Al-43Zn-2Si镀层,研究了表面镀层的显微形貌、物相组成和耐腐蚀性能。结果表明,Q235钢板基材表面镀层较为平整,无明显凹凸,局部区域存在分散的显微凹陷或针孔;经过热浸镀处理后镀层已经覆盖Q235钢表面,表面镀层中只有Al和Zn相,且灰黑色区域是富Al相,灰白色区域为富Zn相;在Q235钢镀层腐蚀时镀层表面灰白色富Zn相优先腐蚀,随后才发生富Al相和化合物相的腐蚀,最终造成腐蚀介质渗漏而造成Q235钢基体的腐蚀破坏。     

海洋大气中钢结构用锌铝伪合金喷涂层防腐蚀体系

高铝含量的锌铝伪合金喷涂层可采用大功率二次风熔丝喷涂工艺获得,适用于海洋大气中的钢结构。长达16 000 h的加速盐雾试验表明,该涂层是一种长效防腐涂层,据推算,在海洋大气条件下,其寿命可达80年。为确保防腐蚀效果,应提高锌铝伪合金喷涂层中铝的含量,经测定,我国目前锌铝伪合金喷涂层表面的铝、锌氧化物体积分数之和已达到70%。     

45钢热浸渗铝渗层厚度分析

采用正交回归设计实验方法,研究了浸渗时间和热扩散时间对45钢浸渗铝渗层厚度的影响规律,建立了渗层回归方程。结果表明,浸渗时间越长,扩散时间越长,渗层厚度越大,渗层逐渐出现了空洞和裂纹,最佳浸渗工艺参数为：浸渗2min,扩散2h。     

不锈钢表面冷喷涂铜涂层制备及性能研究

目的 通过工艺的匹配优化,采用冷喷涂技术在不锈钢表面制备高结合强度铜涂层,并研究热处理工艺对不锈钢表面冷喷涂铜涂层组织及性能的影响规律。方法 分别以高纯氮气和氦气作为加速气体,通过冷喷涂技术,在1 mm厚的304不锈钢基体表面制备铜涂层。采用光学显微镜(OM)对涂层的孔隙率及微观组织结构进行表征。采用场发射扫描电子显微镜(FESEM)对涂层拉伸断面结构进行分析。借助维氏显微硬度仪、万能拉伸试验机和涡流导电仪测试分析退火热处理工艺对不锈钢基体表面冷喷涂铜涂层硬度、结合强度和电导率的影响规律。结果 利用氮气作为加速气体,在薄304不锈钢基体上获得铜涂层困难,涂层形成后,易发生整体剥落。使用氦气作为加速气体,可在薄304不锈钢板表面成功制备结合强度高于81.7 MPa、硬度为99.6HV0.1、孔隙率小于0.1%的高致密铜涂层。退火热处理引起涂层组织再结晶,可显著消除冷喷涂过程中的加工硬化影响。随着热处理温度从300℃上升到500℃,涂层硬度由99.6HV0.1下降至63.7HV0.1。退火温度为400℃时,涂层导电率最优(93.94%IACS)。当热处理温度升高到500℃,涂层导电率异常下...     

碳钢表面等离子喷涂Cr_2O_3涂层及其耐腐蚀性能

利用等离子喷涂技术在45~#钢表面喷涂Cr_2O_3涂层。用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)等方法表征了涂层的微观形貌、表面元素组成以及相结构;测量了涂层的显微硬度;采用CS300P型电化学工作站检测了Cr_2O_3涂层的耐蚀性能。结果表明,在45~#钢表面等离子喷涂Cr_2O_3涂层的厚度约为100μm,相成分主要是Cr_2O_3;显微硬度值达到莫氏9级;喷涂Cr_2O_3涂层后的试样腐蚀速率显著降低,耐蚀性能明显提高。     

养兔场兔笼用Q235钢表面防锈蚀涂层的制备及其性能研究

目的针对养兔场兔笼用Q235钢焊接处表面易锈蚀问题,利用带锈涂料在其表面制备防锈蚀涂层以提高其耐腐蚀能力。方法利用磷酸酯单体和丙烯酸及其脂类单体与乳化液混合得到防锈涂料,按照GB/T 4054—2008在Q235钢表面进行涂覆。通过划圈仪参照GB 1720—1979评价涂层结合力,依据GB/T 6739—2006利用铅笔硬度测定涂层的硬度,通过涡流测厚仪测定涂层厚度,通过烟雾试验、NMP试验、EIS试验、Machu试验评价涂层的耐蚀性能。结果在Q235钢表面制备的防锈蚀涂层与基体的结合力为1级,结合强度高,涂层硬度5级,厚度约为12μm,Machu试验结果表明涂层腐蚀区域较小,显示出较好的抗腐蚀性能。涂层试样经过120 h的NMP试验后依然保持较好的完整度,表现出较好的耐溶胀性能。EIS试验结果说明涂层试样阻抗模值明显低于Q235钢,体现出较好的耐蚀性能。试样涂层经过240 h的盐雾试验后保持完整,体现出较好的耐蚀性能。结论在Q235钢表面制备防锈蚀涂层后,试样的耐蚀性能得到大幅提高。     

Tribological Behavior of Aluminum Slurry Coating on 300M Steel

Al slurry coatings, an alternative of Cd coating to protect against corrosion in the aerospace industry, are currently being explored to satisfy the stringent technology and safety requirements for aeronautical applications. The results of salt fog corrosion exposure, fluid corrosion exposure (immersion), humidity resistance, electrical conductivity, galvanic corrosion, embrittlement, and fatigue indicate that Al slurry coatings can be used as an alternative of Cd coatings. However, the tribological property of Al slurry coatings has still not been investigated. Two types of aluminum slurry coatings on 300M steel were produced using the innovative technological process and characterized by scanning electron microscope, nanoindentation tests, and adhesion tests. The H/E and H ³/E ² ratios of the two-layer Al slurry-coated sample were almost four times higher than the Cd-Ti plating-coated sample. The dry wear test results show that the friction coefficient of the two-layer Al slurry coating independently from the load was lower than the Cd-Ti plating. The width of the wear track of the two-layer Al slurry coating was significantly narrower, only 62% of the Cd-Ti plating wear scar. Compared to the Cd-Ti plating, an excellent wear resistance of the two-layer Al slurry coating can be attributed to its high resistance to plastic deformation and good load-bearing capacity. The results indicate that the two-layer Al slurry coating is an excellent alternative to Cd coatings in the aerospace industry.     

Investigation of the effect of SF6 gaseous halide on the process of MAG welding S235JR carbon steel

The results of investigation of the process of MAG welding S235JR carbon steel with the addition of SF₆ gaseous sulphur hexafluoride with concentrations from 1.6 to 6.4% carbon dioxide are described. The aim of the investigations was to improve the droplet metal transfer and the formation of the welded joint in MAG CO₂ welding in carbon dioxide. The addition of the SF₆ sulphur hexafluoride to the carbon dioxide changes the process of melting of the electrodes, decreases the extent of splashing and shortens the short-circuiting time. The droplet transfer frequency increases by up to 1.6 times, the depth of penetration increases to 66% and the width of the welded joint decreases to 36%. The welding current increases in a wide range of the welding conditions, the arc voltage decreases, together with the amplitude of the deviation of the current and arc voltage     

铝合金插铣铣削力建模与分析

插铣因其特有的优点及近年来技术方面的逐渐成熟，其应用也越来越为广泛。但有关插铣的理论研究尚待逐渐完善，为实际加工提供可靠的理论依据。文章以铝合金的加工为例，利用Labview软件对数据的任意读取、时频分析、前处理等功能，通过对铝合金插铣铣削力的实验测量，并利用统计分析软件SPSS进行回归分析和检验，对插铣过程中铣削力随切削参数的变化而变化的规律进行了研究。     

Q235钢经溶液微弧渗氮的组织和硬度研究

Q235钢试样在溶液中进行快速微弧渗氮;用高分辨摄像机观察了渗氮过程,利用金相显微镜、扫描电镜、能谱分析仪及显微硬度计分别观察和分析了试样表面的金相组织、渗层组织变化及试样表面的硬度变化,探讨了溶液中快速微弧渗氮的机理。结果表明,在电压200 V对试样微弧渗氮40 min后,试样表面化合物层的硬度能达到400 HV左右,化合物层氮元素含量明显提高。     

Q235钢表面熔盐电镀铝及其耐蚀性的研究

将Q235钢试样分别经150℃的AlCl3-NaCl-KCl熔盐和800℃的Al和NaCl-KCl熔盐处理后,可在试样表面获得电镀铝层。对电镀铝层的耐蚀性进行了研究,结果表明,无论是低温电镀还是高温电镀,电镀铝层的厚度都随电流密度的增大和电镀时间的延长而增加,镀层厚度和电镀时问的平方根呈线性关系,而且其耐蚀性得到显著的提高。