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无取向硅钢铬酸镁绝缘涂层高温固化工艺 总被引:1,自引:0,他引:1
为了确保硅钢铬酸盐涂料的环保性,需要严格控制涂料的固化工艺,保证涂料固化过程中涂料中的六价铬充分转化为三价铬。对涂料及原料进行热重分析(TG)及差示扫描量热法分析(DSC)。结果表明,MgO与铬酐混合转化为MgCrO4,使六价铬稳定性增强,其中大部分Cr6+转变为Cr3+发生在620~700℃,在450~500℃高于铬酐发生大量失重,因此必须加入还原剂保证涂料中六价铬被充分还原;超过360℃后树脂会发生分解,因此实际板温不能超过360℃;加入了还原剂的整体涂料的失重温度区间主要在260~320℃,因此涂料固化时钢板的实际温度最佳区间为320~360℃。 相似文献
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镀铬问世以来,镀液配方中铬酐含量较高:250-350克/升(简称高浓度镀铬).这种高浓度镀铬工艺成熟,能满足铬层质量要求,但在镀铬过程中,80%左右的铬酐消耗在镀铬的抽风和零件出槽洗涤的废水之中,既浪费了铬酐,又带来严重的公害.此外高浓度镀铬成本高,限极电流效率低.为了克服上述弊病,我厂采用了快速低浓度镀铬新工艺,现介绍如下. 相似文献
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利用非对称双极脉冲磁控溅射技术,双极分别接纯铬靶和纯铝靶,通过调整两靶的功率,以反应溅射的方式沉积不同铬铝比的氮化铬铝涂层。研究不同Al含量的氮化铬铝涂层的结构和硬度。所获得的涂层依次为Cr0.95Al0.05N、Cr0.9Al0.1N、Cr0.83Al0.17N和Cr0.75Al0.25N,均为B1NaCl结构,(220)为主要的织构取向。随着涂层中Al含量的增加,涂层表面突起的尺寸逐渐降低,涂层趋于光滑致密;低Al含量涂层为柱状晶结构,随Al含量提高,涂层结构更加致密,并向等轴晶结构转变。涂层硬度随Al含量的提高先增加后降低,Cr0.83Al0.17N涂层表现出最高的硬度,维氏硬度达到33GPa以上。 相似文献
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To improve the corrosion resistance of phosphate coatings, the phosphated hot-dip galvanized (HDG) sheets were post-sealed with sodium silicate (water glass) solutions. The morphology and chemical composition of the composite coatings was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The effect of sodium silicate post-sealing treatment on the corrosion behaviors of phosphate coatings was investigated by neutral spray salt (NSS) tests and electrochemical measurements. The results show that after the silicate post-treatment the pores among zinc phosphate crystals are sealed with the films containing Si, P, O and Zn, leading to the formation of the continuous composite coatings on the surface of HDG steel. The corrosion resistance of the composite coatings depending on concentration of sodium silicate and post-sealing time is greatly improved by the silicate post-treatment. The optimum concentration of silicate and post-sealing time are 5 g/L and 10 min, respectively. Both the anodic and cathodic processes of zinc corrosion on the samples are suppressed conspicuously, and the synergistic protection effect of the single phosphate coatings and the single silicate films is evident. Moreover, the low frequency inductive loop in electrochemical impedance spectroscopy (EIS) is disappeared and the electrochemical impedance values are increased for more than one order of magnitude. The corrosion protection of the composite coatings is comparable to that provided by the chromic acid post-treatment. 相似文献
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The paper reports work on the electrodeposition of decorative chromium coatings from solutions of trivalent chromium compounds. Work on aqueous sulphate-based electrolytes showed that pH maintenance was the critical factor governing the production of sound decorative deposits. Wholly aqueous solutions could not be stabilized by buffers of the usual kind. Dimethylamido buffers were found to stabilize the pH of chromic chloride solutions at an acceptable value for plating. A solution based on aqueous chromic chloride containing 40% v/v of of dimethylformamide (DMF), one of these buffers, has been developed and possesses excellent plating characteristics. 相似文献
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电化学沉积法制备钛基HA涂层 总被引:5,自引:0,他引:5
在钛基材表面获得羟基磷灰石(HA)涂层以改善钛与生物体的相容性,本项工作采用电沉积的方法在阳极氧化处理过的钛基体上制备了羟基磷灰石涂层。用扫描电子显微镜(SEM)、X射线衍射(XRD)等手段对涂层进行了表征。试验结果表明:电沉积初期的羟基磷灰石涂层呈多孔层片状:随电压、时间、电解液浓度的增大,涂层变厚,层片呈花瓣状发散排列:对基体阳极氧化处理有助于提高钛基与涂层的结合强度。 相似文献
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采用羟基丙烯酸酯树脂为涂料用树脂,在配方中添加鳞片填料,观察三种鳞片填料的粒径以及填料在涂层中的分布,对比试验了不同鳞片填料涂层的耐阴极剥离性能。结果表明,玻璃鳞片及不锈钢鳞片对涂层的耐阴极剥离性能的提高要好于云母鳞片;鳞片添加总量控制在涂料固体含量质量分数的40%左右时,涂层达到较好的防腐蚀性能。 相似文献
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R. V. Moshtev 《工业材料与腐蚀》1967,18(11):978-983
Zinc phosphate coatings from supersaturated baths The author studied the properties of supersaturated phosphating solutions containing zinc phosphate being used for phosphating steel. The study included the influence of the solution variables, and in particular of the ferrous ion concentration, on the supersaturation and the coating properties. The accelerating effect of supersaturation is so strong that heavy, dense, and fine grain coatings are obtained without oxidants and at temperatures as low as + 10° C. Some aspects of the kinetics and the mechanism of coating formation in supersaturated solutions are discussed. Supersaturated phosphating solutions with zinc phosphate may find practical application, particularly where a high degree of protection is desired. 相似文献
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St.- Lindqvist 《工业材料与腐蚀》1980,31(7):524-527
The cathodic protection effect of zinc in zinc pigmented coatings can be clearly recognized above a certain pigment concentration. According to the results obtained during potentiostatic polarization experiments such an effect can be expected above 90% Zn. This effect will still be present after 30 days in sodium chloride solution, provided the original concentration is 93%, while the protective effect is lossed after this time in the case of 91% Zn. The potentiostatic methods are clearly superiour to a resistance method used preferentially and can be recommended for formulation of coating materials and for testing such coating materials and coatings. 相似文献
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采用扫描电镜(SEM)、X射线衍射(XRD)及能谱(EDX)和电化学测试的方法,研究了稀土硝酸盐(REN)对6061铝合金锌系磷化成膜过程的影响,结果表明,少量的稀土硝酸盐添加到磷化液中可以提高磷化成膜速度和细化晶粒,改变磷化膜的组成,但稀土硝酸盐本身并不构成磷化膜的组成成分,它实质上是具有良好载氧能力的促进剂,具有良好的成核促进作用和阴极去极化作用.与在不含稀土硝酸盐的磷化液中所形成的磷化膜相比,铝合金在含有稀土硝酸盐的磷化液中所形成的磷化膜具有较低的化学活性,其耐蚀性得到提高,在所研究的工艺条件下,最佳硝酸盐含量为20~40 mg/L. 相似文献
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Hot‐dipped galvanized zinc and zinc alloy coatings were used as protective metallic coatings for steel structures in seawater in China. Corrosion of the two coatings immersed in sea water in Qingdao and Xiamen for 6 years were introduced and analyzed, which provides a basis for further development and applications of these coatings in China. Tests proved that the anti‐corrosion performance of the hot‐dipped low alloy zinc coatings (aluminum content less than or equal to 10 wt%) is equal to or even lower than that of the pure zinc sheet, while the performance of the hot‐dipped high alloy zinc coatings is higher than that of the pure zinc sheet. The hot‐dipped high alloy zinc coatings can be further developed for optimal performance in the future. 相似文献