金属陶瓷涂层耐蚀性能研究

采用溶胶－凝胶浸渍提拉法在不锈钢、纯铜及铝合金基体上制备具有保护性的ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、Ａｌ２Ｏ３及ＳｉＯ２－ＴｉＯ２陶瓷涂层,利用阳极极化曲线的、循环动电位极曲线、点蚀电位的测量以及三氯化铁和５％硫酸介质中的腐蚀试验研究了所得陶瓷涂层的耐蚀性。结果表明,这些陶瓷涂层能大幅芳提高金属基体在各种腐蚀介的耐蚀性。     

不同溶剂对锌基涂层耐蚀性的影响

利用片状锌粉、铝粉、铬酐及其它有机物配制的锌基涂料具有良好的结合力和耐蚀性。探讨了不同溶剂对涂层的影响，涂层的耐蚀性以及其形貌结构。结果表明，所得涂层致密，耐蚀性比同厚度的锌镀层及镀锌钝化层要高得多。     

电泳沉积氧化铝陶瓷涂层的制备及耐腐蚀性能

以氧化铝溶胶为前驱体,采用电泳沉积和低温煅烧法在低碳钢基体上制备了氧化铝陶瓷涂层,并对其成分、表面形貌及耐蚀性进行了研究。结果表明,将低碳钢片置于以乙醇作为分散介质的0.45mol/L氧化铝溶胶中,在60V恒电位下沉积180s后,再于马弗炉中700°C下煅烧5min,所制得的氧化铝陶瓷涂层在2mol/L盐酸溶液中具有良好的耐蚀性。     

硅酸盐矿物/TiB2复相陶瓷涂层的制备及耐蚀性能研究

本文采用热化学反应法在Q235钢基体表面分别制备了硅酸盐矿物陶瓷涂层和添加Al-TiO2-B2O3反应体系复相陶瓷涂层,用XRD分析其相结构,并研究了涂层的耐蚀性。结果表明,硅酸盐矿物/TiB2复相陶瓷涂层有TiB2、FeNi3、CaNi0.5Si1.5等新相产生。耐酸、碱、盐性相对基体分别提高8.6倍,4.4倍,6.2倍,耐蚀性优于纯硅酸盐矿物涂层。     

溶胶—凝胶法与金属表面改性

以２９篇参考文献概述了溶胶－凝胶涂层技术，溶胶－凝胶涂层可以提高玻璃、陶瓷、金属基板的耐蚀性，氧化性，耐磨性和拒水性能。     

热化学反应法制备纳米复合陶瓷涂层及性能研究

采用热化学反应法在Q235钢上制备纳米复合陶瓷涂层,对涂层进行结构分析及性能测试。试验结果表明:涂层在600℃固化产生了新陶瓷相;涂层较致密,涂层与基体结合良好;涂层大大提高了基体的耐蚀性和耐磨性。     

溶胶-凝胶法制作陶瓷涂层硬质合金刀具

以异丙醇铝为前驱物，将溶胶－凝胶工艺应用于硬质合金刀片涂层，研制成功一种新型的陶瓷涂层刀片。使用浸渍提拉法对刀具基体进行涂层，在基休表面获得勃姆石凝胶膜，经１２００℃热处理后可以得到厚度适宜的α－ＡＩ２Ｏ３涂层，支完整，无宏观缺陷，并且后可以得到厚度适宜的α－ＡＩ２Ｏ３涂层，涂我宏观缺陷，并且在初步的切削实验中显示出一人而为涂层恨具制造展示了一种全新的涂层方法。利用扫描电子显微镜（ＳＥＭ０观察了涂     

影响旋转法制备K2O—PbO—SiO2溶胶—凝胶涂层性能的因素

用正硅酸乙酯、醋酸铅和醛酸钾制备了Ｋ２Ｏ－ＰｂＯ－ＳｉＯ２溶胶。溶胶－凝胶涂层用离心法涂覆到平板玻璃上。涂膜玻璃的折射率随溶胶－凝胶涂层中铅含量的增加而提高。讨论了溶胶－凝胶涂层的厚度和均匀性与溶胶粘度和离心转速的关系。     

溶胶-凝胶封孔处理后AZ91D镁合金微弧氧化膜的耐蚀性

以正硅酸乙酯(TEOS)为前躯体,采用溶胶-凝胶技术在微弧氧化处理的AZ91D镁合金基体表面制备了SiO<,2>封孔涂层.采用热重(TG)、能谱(EDS)和扫描电镜(SEM)对凝胶热性能和涂层的成分及微观形貌进行了分析,并对封孔处理前后的试样进行耐蚀性检测.结果表明,封孔处理后,镁合金耐0.1 mol/L硫酸的时间超过...     

金属表面电泳法制备陶瓷涂层的研究进展

陶瓷涂层具有耐磨、耐蚀、耐高温和抗微生物侵蚀等性能。介绍了国内外用电泳沉积法制备生物陶瓷涂层、碳化硅陶瓷涂层、氧化钛陶瓷涂层、氧化铝陶瓷涂层、氧化硅陶瓷涂层及氧化锆陶瓷涂层的研究进展,揭示了防腐领域中陶瓷涂层存在的问题,提出了解决方法并展望了未来的研究方向。     

Screening study of spray solution parameters for depositing cerium-based conversion coatings on Al alloy 2024-T3

Cerium-based conversion coatings were deposited on aluminum alloy 2024-T3 by a spray process using a solution containing cerium chloride, hydrogen peroxide, and gelatin. As deposited coatings were composed of hydrated cerium oxide and were post-treated in a phosphate solution to improve corrosion performance. Coating solution parameters, including the pH (1–2.5), cerium chloride concentration (0.025–0.125 M), and hydrogen peroxide content (0–1.2 M), were varied to investigate the effect(s) of solution parameters on the corrosion performance of the post-treated coatings. Results indicated that thickness of coatings deposited from solutions with different pH values were similar, while coating thickness increased with increasing concentration of cerium chloride and hydrogen peroxide in the solutions. Electrochemical impedance spectroscopy and observations of the surface appearances of the coatings indicated that coatings deposited from solutions with a pH 2, a cerium concentration of 0.1 M, and a hydrogen peroxide concentration of 0.8 M exhibited the best corrosion resistance.     

Effect of ultra accurate control of electrolyte temperature on the performance of micro arc oxidation ceramic coatings

The technique of micro arc oxidation (MAO) uses arc discharge and high-voltage breakdown to produce a ceramic layer on valve metal surfaces. However, the common method of MAO requires immersing the workpiece in an electrolyte solution, which can result in elevated temperatures due to the arc discharge, thus negatively affecting the coating's quality and performance. This article investigates the influence of electrolyte temperature on the performance of MAO ceramic coatings, with the assistance of a robotic arm enabling valve metal reaction without immersion in the electrolyte, and precise control of electrolyte temperature through a MAO temperature monitoring system. Various techniques, such as scanning electron microscopy (SEM), hardness testing, electrochemical corrosion experiments, and friction-wear experiments, were utilized to characterize the performance of the prepared coating. The results indicate a nonlinear correlation between the temperature of the electrolyte and the thickness and hardness of the ceramic coating. The corrosion and wear resistance of the MAO ceramic coatings initially improve with increasing electrolyte temperature but eventually deteriorate. At an electrolyte temperature of 40 °C, the MAO ceramic coating exhibits the optimal corrosion and wear resistance. The variation in electrolyte temperature affects the reactivity of the electrolyte ions, leading to changes in the morphology and properties of the resulting MAO ceramic coating. These findings offer valuable insights into the interaction mechanism between electrolyte temperature and the properties of the resulting MAO ceramic coating. This is of great significance in optimizing the MAO process for specific applications and improving the overall performance of ceramic coatings.     

Corrosion resistance of compositionally modulated multilayered Zn–Ni alloys deposited from a single bath

By consecutive deposition at two different current densities from a single sulfate–chloride bath, compositionally modulated multilayered (CMM) coatings of Zn–Ni alloys, with different number, thickness and sequence of the sublayers were obtained. The corrosion resistance of the coatings was studied by potentiodynamic dissolution and by corrosion potential measurement. In the current–potential (stripping) curves two well-defined peaks were observed. With increase in the number of sublayers, regardless of their individual thickness, the correlation between the amount of Zn, dissolved at more negative potentials and the whole amount of the metal in the CMM coatings, decreases. The corrosion potentials of CMM coatings are most positive (–0.940 V vs SSE) when they end with a Zn–Ni18% oversublayer. As a result of the alternation of Zn–Ni alloy sublayers with different Ni content the obtained CMM coatings have increased corrosion resistance in comparison with the monolayer coatings of the composing alloys.     

Electrochemical and morphological properties of zirconium conversion coating in the presence of nickel ions on galvanized steel

A hexafluorozirconic acid-based conversion coating was applied on a galvanized steel substrate and the influence of nickel ion from nickel sulfate solution (in zirconium solution and in a separate solution) on the corrosion resistance behavior and morphology of zirconium conversion coating was investigated. Electrochemical impedance spectroscopy and DC polarization were conducted in 3.5 wt% NaCl solution in order to optimize practical conditions of zirconium conversion coating and NiSO₄ solution on the galvanized steel substrate. Field emission scanning electron microscopy and X-ray photoelectron spectroscopy were employed to study the morphology and composition of the coated surfaces. Results revealed that the conversion coating obtained from solution containing zirconium and nickel ions (Zr + Ni) did not improve corrosion resistance and uniformity of the coating in comparison with Zr conversion coating in optimized condition. However, a positive effect was obtained from samples coated with separate solutions of zirconium and nickel (Zr–Ni). Improved corrosion resistance and morphology of Zr-based conversion coating were observed in Ni²⁺ concentration, pH, and immersion time of 10 g/L, 6 and 300 s, respectively. Morphology and surface composition analysis proved that two separate layers of conversion coating containing zirconium, zinc, and nickel oxide/hydroxide compounds were formed in the case samples that were treated by separate solutions. This led to better uniformity and higher thickness of the coating. Finally, adhesion strength of epoxy organic coating on galvanized steel with and without conversion coating was investigated by pull-off measurement. Zr–Ni conversion coating in optimum conditions had a positive effect on adhesion of organic coating in comparison with blank sample and samples pretreated with Zr and Zr + Ni conversion coatings through increased surface roughness and physical interlocking.     

Investigation on copper corrosion behaviour in industrial waters by electrochemical noise analysis

This paper represents an attempt to apply electrochemical noise analysis to monitor copper corrosion rates in solutions simulating near neutral or acidic industrial waters, containing chloride, sulphate and bicarbonate ions. The very low noise levels characterizing these systems make the evaluation of the noise resistance possible only with a four electrode arrangement, where the electrode couples used to detect the voltage and current fluctuations have different surface areas. This arrangement is probably a handicap to the evaluation of the polarization resistance values from noise resistance data. Cyclic voltammetries were carried out in order to investigate the nature of the corrosion products obtained in solutions with different pH.     

Electrochemical characterization of hydroxyapatite coatings on HNO3 passivated 316L SS for implant applications

Type 316L SS play a key role in the bone replacement surgery due to its excellent mechanical features, availability at low cost and ease of fabrication. However it fails miserably in vivo conditions due to corrosion-related problems. Hence an alternative method on the development of hydroxyapatite (HAP) coatings has been elucidated to impart corrosion resistance of the base metal and ensure biocompatibility of the ceramic on the metal surface. This also could not match the implant at the host site due to the continuous interaction of hostile environment with the implant and results in the dissolution of both ceramic and metal. An artificially induced passive layer on the metal surface prior to coating may improve the nature of implant on the resistance to corrosion. In the present study, the effect of HNO₃ treatments on 316L SS and the coatings on passivated 316L SS is being explored. Electrochemical studies involving cyclic anodic polarization experiments and impedance analysis in Ringer's solution were done to determine the corrosion resistance of the coatings. The leach out characteristics of the coatings was determined at the impressed potential. The results have indicated the efficiency of HAP coatings on HNO₃-treated surface.     

Electrochemical corrosion behavior of chromium-phosphorus coatings electrodeposited from trivalent chromium baths

Chromium-phosphorus (Cr-P) coatings are electrodeposited from trivalent Cr (Cr(III)) baths containing hypophosphite. The electrochemical corrosion behavior of Cr-P coatings, traditional Cr coatings deposited in hexavalent Cr (Cr(VI)) baths, and chromium-carbon (Cr-C) coatings deposited in Cr(III) baths containing formate are studied by measuring potentiodynamic polarization curves in a 10 wt% HCl solution. The composition and morphology of the coating surface layers are investigated by X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM), respectively. The results of electrochemical tests show that Cr-P coatings exhibit better corrosion resistance than traditional Cr and Cr-C coatings, which is characterized by a lower critical current density, lower passive current density, and lager passive potential range. XPS and SEM analyses confirm that the excellent corrosion resistance of Cr-P coatings is attributed to the formation of a phosphide passive film, which has high stability and self-repairing ability, and can act as a “buffer” to reject the penetration of chloride ions.     

Influence of chloride ion concentration on the electrochemical corrosion behaviour of plasma electrolytic oxidation coated AM50 magnesium alloy

The electrochemical degradation of a silicate- and a phosphate-based plasma electrolytic oxidation (PEO) coated AM50 magnesium alloy obtained using a pulsed DC power supply was investigated using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) in NaCl solutions of different chloride ion concentrations viz., 0.01 M, 0.1 M, 0.5 M and 1 M. The surface of the PEO coated specimens after 50 h of immersion/EIS testing was examined by optical microscopy and scanning electron microscopy. The results showed that the corrosion deterioration of PEO coated magnesium alloy in NaCl solutions was significantly influenced by chloride ion concentration. The silicate-based coating was found to offer a superior corrosion resistance to the magnesium substrate than the phosphate-based coatings in lower chloride ion concentration NaCl solutions (0.01 M and 0.1 M NaCl). On the other hand both these PEO coatings were found to be highly susceptible to localized damage, and could not provide an effective corrosion protection to Mg alloy substrate in solutions containing higher chloride concentrations (0.5 M and 1 M). The extent of localized damage was observed to be more with increase in chloride concentration in both the cases.     

Evolution of corrosion on microstructure of ceramic coating produced by plasma electrolytic oxidation in molten salt

Low corrosion resistance in an Al alloy is usually overcome with the help of an Al oxide coating. Plasma electrolytic oxidation (PEO) is a highly promising environment-friendly method to achieve a ceramic surface. Traditionally, PEO is carried out in an aqueous electrolyte; however, in this study, PEO was conducted in a molten salt. This approach conserved more energy and led the formation of a pure oxide coating, as confirmed by subsequent phase analysis. The obtained ceramic coating contained two sublayers: a porous outer sublayer and a dense inner sublayer. A study of corrosion evolution was performed on oxide-coated alloys immersed in a NaCl solution for different durations. The corrosion behavior characterized by electrochemical impedance spectroscopy (EIS) was related to the changes in the surface morphology changes examined by electron microscopy. The appearance of pits on the oxide surface was attributed to the adsorption and incorporation theory, previously described for Al alloys. This study revealed that the progress of the corrosion attack by chloride ions affects both sublayers; the thickness of the outer sublayer decreased, and the inner sublayer became more compact, resulting in high resistance properties.