二种热喷涂镍铝合金丝涂层的性能比较

热喷涂涂层的制备方法有许多。其中火焰喷涂和电弧喷涂是比较常用的方法。本文通过对镍铝火焰与电弧喷涂合金涂层的制备与性能的比较，阐述了电弧喷涂涂层结合强度，硬度，热疲劳寿命均比火焰喷涂涂层高。     

火焰喷涂在纯铜表面获得TiO_2/Cu梯度涂层的工艺与显微组织分析

利用氧乙炔火焰喷涂工艺,在纯铜表面反应形成高硬度、高耐磨性的Ti O2/Cu梯度复合涂层。试验结果表明,火焰喷涂反应生成Ti O2/Cu梯度涂层为典型波浪状多层喷涂组织,涂层组织呈梯度连续变化,梯度层间结合情况良好,无明显界面;涂层与基体有明显的宏观层间界面,结合情况较好。火焰喷涂反应生成的Ti O2/Cu梯度涂层中存在气孔、夹杂等缺陷。     

火焰喷涂聚酰胺12/n-SiO2复合涂层工艺及性能

采用火焰喷涂法制备了聚酰胺12(PA12)及聚酰胺12/纳米SiO2(n-SiO2)复合涂层,并利用电子拉力机、摩擦磨损试验机、红外光谱仪(FTIR)和示差扫描量热仪(DSC)等对涂层的结构与性能进行了研究.红外光谱分析表明PA12及PA12/n-SiO2粉末在火焰喷涂过程中没有发生氧化或降解反应,表明火焰喷涂法适宜制备PA12及PA12/n-SiO2复合涂层;DSC分析结果表明n-SiO2具有成核剂作用,能提高PA12大分子的结晶速度及结晶度;涂层力学性能及摩擦磨损性能分析表明n-SiO2能提高涂层的力学性能,改善涂层的耐老化性能和摩擦磨损性能.当n-SiO2添加量为1.5%(质量)时,涂层综合性能最佳.     

HVOF喷涂用于提高锅炉换热面耐磨损耐腐蚀性能综述

火力发电是我国的主要发电方式,在燃用煤、生物质等固体燃料时会面临锅炉换热面的冲蚀磨损或腐蚀问题,导致管道失效停炉,严重影响了电厂的安全稳定运行。超声速火焰（HVOF）喷涂作为热喷涂工艺的一种,可以通过在换热管道表面添加防护涂层来缓解磨损或腐蚀问题。因其制备的涂层具有与基体结合强度高、孔隙率低等优异的特点,在锅炉换热面的耐磨损耐腐蚀方面研究及应用前景广阔。综述了HVOF喷涂的发展、工艺流程以及涂层的特性,并重点总结了用于提升锅炉换热面耐磨损耐腐蚀性能的HVOF涂层材料,以及不同材料应用时需要考虑的环境因素。最后从工艺优化、材料进步以及实验方法创新三个方面对HVOF工艺在锅炉换热面上的应用做出展望。     

抗冲蚀性热喷涂金属陶瓷涂层研究进展

热喷涂技术是利用热源加热喷涂材料在基体表面制备涂层的方法。火焰喷涂、等离子喷涂和电弧喷涂是常用的热喷涂技术。金属陶瓷兼有陶瓷材料的高硬度、高熔点及金属的韧性等优点,常用于制备材料表面抗冲蚀涂层,其中WC系和Cr_3C_2系金属陶瓷较为常用。冲蚀工艺参数、喷涂工艺参数、喷涂材料性能对金属陶瓷涂层的抗冲蚀性能均有影响。如何通过调控材料结构和喷涂工艺参数是提高金属陶瓷涂层抗冲蚀性的关键。     

火焰喷涂在纯铜表面获得TiO_2/Cu梯度涂层的性能分析

利用氧乙炔火焰喷涂工艺,在纯铜表面反应形成高硬度、高耐磨性的TiO2/Cu梯度复合涂层。分析了涂层的结合性能,发现多层涂层更有优势。分析了涂层的摩擦磨损性能,发现涂层的耐磨性优于GCr15,并且涂层的硬度越高越耐磨。     

火焰喷涂聚酰胺12/n-SiO2复合涂层工艺及性能

采用火焰喷涂法制备了聚酰胺12 (PA12)及聚酰胺12/纳米SiO₂ (n-SiO₂)复合涂层,并利用电子拉力机、摩擦磨损试验机、红外光谱仪（FTIR）和示差扫描量热仪（DSC）等对涂层的结构与性能进行了研究。红外光谱分析表明PA12及PA12/ n-SiO₂粉末在火焰喷涂过程中没有发生氧化或降解反应,表明火焰喷涂法适宜制备PA12及PA12/n-SiO2复合涂层;DSC分析结果表明n-SiO₂具有成核剂作用,能提高PA12大分子的结晶速度及结晶度;涂层力学性能及摩擦磨损性能分析表明n-SiO₂能提高涂层的力学性能,改善涂层的耐老化性能和摩擦磨损性能。当n-SiO₂添加量为1.5%（质量）时,涂层综合性能最佳。     

火焰喷涂型表面多孔管的性能研究

对比了火焰喷涂型表面多孔管和烧结型表面多孔管的制造方法,分析了这两种表面多孔管多孔涂层的表面形貌和涂层结合强度的差异,并对火焰喷涂型表面多孔管的沸腾传热性能进行了实验研究。     

超音速等离子喷涂制备陶瓷涂层的研究进展

超音速等离子喷涂技术由于具有高温、高速的独特优点,且制备的陶瓷涂层结合强度和致密度高,孔隙率低,具有优良的耐磨损、耐腐蚀、抗氧化和热冲击性能,已成为一些发达国家竞相研究的热点.本文介绍了常用的陶瓷涂层材料,综述了超音速等离子喷涂技术及其制备陶瓷涂层的工艺特点,并对超音速等离子喷涂制备高性能陶瓷涂层的发展趋势进行了展望.     

超音速火焰喷涂316L不锈钢涂层在零件尺寸修复中的应用

为了解决装备核心零部件因磨损、消除腐蚀等带来的尺寸超差问题,制作超音速火焰喷涂316L不锈钢涂层性能试样,对试样涂层的形貌、硬度、耐蚀性开展试验检测研究。结果表明,涂层具有与25Cr3MoA接近的硬度和比30CrMnSiNi2A更好的耐蚀性能。由此,提出采用超音速火焰喷涂316L不锈钢涂层进行零件尺寸修复,制定了可行的修理方案和技术路线,确定了修理工序和参数,形成了相关技术文件,用于指导零件尺寸修复,并在油泵轴和肩轴两类零件上成功应用和装机验证,其性能良好,质量安全。     

Combustion‐thermal‐sprayed recycled poly(ethylene terephthalate)

Thermal‐sprayed polymer coatings have been used as protection against corrosion and wear. In this study, poly(ethylene terephthalate) (PET) powder, which was obtained from postconsumer beverage bottles, was deposited on 1020 steel by low‐velocity flame‐spray technology. The chemical and structural changes in PET due to the thermal‐spray processing were investigated with Fourier transform infrared spectroscopy and X‐ray diffraction. Changes in tribological behavior were examined by pin‐on‐disk testing and three‐dimensional profilometry. The results show that coatings had the same functional groups as the PET beverage bottles. However, the degree of crystallinity was modified. These changes were rationalized in terms of possible structural modifications of the PET polymer. The study showed evidence that the pin‐on‐disk wear developed by an abrasion process through a ploughing mechanism, although a fatigue mechanism could not be disregarded. A low friction coefficient between PET and steel was confirmed. In the as‐sprayed condition, the PET coatings showed higher friction, likely because of a higher coarse debris production rate during the pin‐on‐disk testing. Heat treating the as‐sprayed coating to increase the amorphous PET content improved the sliding behavior by increasing wear resistance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3159–3166, 2004     

Corrosion and Fire Protective Behavior of Advanced Phosphatic Geopolymeric Coating on Mild Steel Substrate

The research objectives of this study were to investigate and compare corrosion and fire protective properties of conventional and advanced phosphatic geopolymeric coating on mild steel substrate using spray coating technique For these studies two composition were developed using conventional geopolymerisation route by adding alkali activator solution to fly ash and six compositions were developed using advanced geopolymerisation process in which water was added to solid precursor powder obtained by together co-ginding of raw materials for a period of 8 h. Coated plates were tested for adhesion strength, water resistance, fire protection and corrosion resistance. Results indicated that coating developed from two passes with thickness 100 ± 15 μm showed better adhesion as compared to single pass and also proved to be promising corrosion protective coating material for mild steel substrate under sea water conditions. The developed material is able to withstand flame for more than 45 min and also no cracks were observed in coating by direct heating on liquefied petroleum gas flame. Thus developed phosphatic geopolymeric material is well suited for protecting the mild steel structures from fire and corrosion.     

Cracking induced tribological behavior changes for the HVOF WC-12Co cermet coatings

HVOF sprayed WC based cermet coatings have been widely used in industries as barriers against wear and hydrodynamic cavitation due to their high hardness and relatively high toughness. However, cracking of the coatings can occur during coating production or in service, which can reduce operational performances. It can be difficult to assess the performance impact due to cracks within the coating and as to whether the cracked coatings should be resprayed or removed from service. In this work, artificial cracks of different widths were introduced to liquid fuel HVOF sprayed WC-12Co coating through uniaxial tension of the coated steel substrate to assess the implications of such cracking. Tribological performances of the cracked coatings were examined using rubber wheel dry abrasion, ‘ball on disc’ sliding wear, and ultrasonic cavitation erosion. The results show that the crack deteriorates the abrasive wear resistance of the coating at the initial stage due to preferable mass loss at the cracks. However, after 30?min of abrasion, all the cracked coatings showed the same wear rate as compared to the non-cracked coating, with the abrasive wear resistance acting independent to the crack characteristics. Because the cracks could store wear debris and thus minimize the debris induced abrasion to the coating surface during sliding wear test, both improvement in wear resistance and reduction in coefficient of friction (COF) were detected in the cracked coatings. During the cavitation test, it was found that the mass loss of the specimen increased significantly (up to 75%)with crack width and density suggesting that the crack presence greatly deteriorated the cavitation resistance of the cermet coatings.     

Corrosion studies on electrochemically deposited PANI and PANI/epoxy coatings on mild steel in acid sulfate solution

The corrosion behavior of mild steel and mild steel covered by electrochemically deposited (a) polyaniline (PANI) film, (b) epoxy coating and (c) PANI/epoxy coating system in 0.1 M sulfuric acid solution were investigated by electrochemical impedance spectroscopy (EIS). Electrochemical deposition of PANI film was performed from aqueous solution of 0.5 M sodium benzoate and 0.1 M aniline at constant current density of 1.5 mA cm⁻². Epoxy coatings on mild steel and mild steel modified by PANI film were deposited at constant voltage. It was shown that thin PANI film had provided good corrosion protection of mild steel in 0.1 M sulfuric acid solution, and could be used for modification of mild steel prior to epoxy coating deposition. The increased corrosion protection of mild steel by PANI/epoxy coating system in the same solution was obtained.     

纳米SiO2对火焰喷涂HDPE涂层热力学性能的影响

利用电子拉力机、红外光谱仪(FTIR)、透射偏光显微镜(POM)和差示扫描量热仪(DSC)等研究了纳米SiO2(n-SiO2)对火焰喷涂HDPE涂层力学及热性能的影响.红外光谱和XRD分析表明,HDPE及HDPFJ/n-SiO2粉末在喷涂的过程中没有发生氧化或降解作用,表明火焰喷涂法适合制备HDPE及HDPE/n-SiO2复合涂层.DSC分析表明,n-SiO2具有异相成核作用,当n-SiO2用量为1.0%时,复合涂层的过冷度由10.92℃下降为10.73℃.     

“Effect of nano-ZnO particles on the corrosion behavior of alkyd-based waterborne coatings”

A nano-composite was formed by incorporating nano-ZnO in a specially developed alkyd-based waterborne coating to different loading levels. The nano-ZnO based composite coatings were applied on mild steel substrate by dipping. The coated panels were subjected to various test environments like salt-spray, humidity, UV and mechanical tests like scratch and abrasion. The improvement in electrochemical performance and mechanical properties of the composite coatings were evaluated using various analytical techniques. FTIR technique was used to investigate the interaction between nano-ZnO particles and the polymer functionalities. Differential scanning calorimetry (DSC) was done to study the curing behavior of nano-composite coatings. SEM and AFM were used to investigate dispersion of nano-ZnO particles and the changes in the surface behavior of the coatings before and after exposure to the test environment. The result showed that, with increase in the concentration of nano-ZnO there was an improvement in the corrosion resistance, UV resistance and mechanical properties of the coatings indicating the positive effect of addition of nano-ZnO particles in the coatings.     

偶联剂对火焰喷塑复合涂层结构和性能的影响

利用拉力试验机、扫描电子显微镜及付里叶变换红外光谱仪,研究了偶联剂TPM对火焰喷涂尼龙1010/石墨复合涂层微观结构、化学结构和力学性能的影响。结果表明,偶联剂TPM能明显改善尼龙1010大分子与石墨之间的相容性,使复合涂层性能得到改善,获得了自拉伸强度大于35MPa,结合强度大于17MPa的复合涂层。     

Characterization of flame‐sprayed PEEK coatings by FTIR‐ATR,DSC and acoustic microscopy

Poly (aryl ether ether ketone) (PEEK) was used as a flame‐sprayed coating, due to its good mechanical properties, low friction coefficient and high thermal stability. Fine polymeric powders are warmed up in oxyacetylene flame and sprayed onto a previously heated aluminium substrate. The degree of crystallinity of PEEK coatings was investigated by differential scanning calorimetry (DSC), according to the rate of cooling after the spraying process. FTIR‐ATR revealed structural modifications, due to interactions between the flame and the polymeric powders. Ultrasonic methods were developed, in particular acoustic microscopy, to examine the variations of mechanical properties at the surface and the defects inside the material. Generally, flame‐sprayed coatings contain a large amount of porosity. In addition, low‐frequency microechography, a non‐destructive technique, is particularly suited to the observation of large defects (exceeding 50 microns) inside the polymeric materials.     

The effect of cationic surfactants in acid cleaning solutions on protective performance and adhesion strength of the subsequent polyurethane coating

The subsequent effect of the use of monomeric cationic surfactants, dodecyltrimethylammonium bromide (DTAB) and its gemini counterpart, 12-4-12, in 1 M sulfamic acid cleaning solution on the corrosion resistance and adhesion strength of polyurethane coating on mild steel surface was studied by salt spray and pull off, respectively. The EIS (electrochemical impedance spectroscopy) was employed to evaluate the corrosion behavior of mild steel during the contact with sulfamic acid solutions. Inhibition performance of DTAB on mild steel at the initial period of immersion was somewhat higher than 12-4-12, while at prolonged immersion period 12-4-12 was more effective than DTAB. The higher protection and adhesion for the coating applied on the mild steel washed with DTAB solution was connected to more rapid adsorption for DTAB than 12-4-12 at short immersion period due to its small molecular weight which resulted in better mobility of DTAB molecules.     

Microstructure evolution and mechanical properties of thermally sprayed coating modified by laser remelting and injection with tungsten carbide

The forming quality of thermally sprayed coatings is often severely impacted by inherent defects, including porosity, microcracks, and mechanical bonding. The poor adhesive strength hinders the utilization of thermal spray technology when fabricating ceramic-reinforced metal matrix composite coatings (MMCCs). Thus, in this study, a negative defocus laser remelting and injection method (LRI) is introduced to modify a thermally sprayed coating with WC ceramics. The microstructure and mechanical property (microhardness, elastic modulus, and wear resistance) evolution of a LRI-modified WC reinforced composite coating is systematically characterized and compared with that for an as-sprayed coating. The LRI method is proven to improve the inherent defects of the initial coating and avoid severe reactions and dissolution of reinforced particles at high temperatures, and can be used to form a high-quality composite coating with a maximum strengthening effect of the ceramic particles. Compared with the initial coating, the elastic modulus and microhardness of the LRI coating are increased by 57.22% and 111.06%, respectively, whereas the abrasion rate is decreased by 54.33%.