Optimisation of metallic pigments in coatings by an electrochemical technique and an investigation of manganese powder as pigment for metal rich primers

Zinc dust and manganese powder as pigments were incorporated in epoxy-polyamide and butyl titanate medium, with different pigment volume concentration (PVC) ranging from 20 to 74. These protective coatings were coated on sand blasted mild steel substrates and immersed in 3 wt.% sodium chloride solution and the corrosion current was measured by the Tafel extrapolation method. From the corrosion current produced by these primers, the optimum level of the pigments in these binders was identified. Thus the protective performance of optimised primers was evaluated on a sand blasted mild steel surface by the Tafel polarisation method in 3 wt.% sodium chloride solution, over different periods of time. The results were found to be comparable with the salt spray test and galvanic current measurements. The manganese powder used for this investigation showed that it could be used as an alternative to zinc powder for metal rich primers.     

化学镀Ni-P-PTFE复合镀层的性能

本文对化学镀ＮｉＰＰＴＦＥ复合镀层的性能作了测定和评价。实验表明，用优化的镀液配方和工艺可获得含ＰＴＦＥ粒子２５～３０％ｖｏｌ的ＮｉＰＰＴＦＥ复合镀层。这种镀层具有优良的结合力和良好的耐蚀性，其硬度随ＰＴＦＥ含量增加而降低，其特别突出的性能是优异的减摩性和耐磨性，是一种具有自润滑功能的表面复合材料。     

Advanced Coatings on Furnace Wall Tubes

Nickel-based self-fluxing alloy coating extends the service life of furnace wall tubes at waste incineration plants due to its excellent corrosion resistance and heat resistance. Fusing of such coatings by induction heating offers improved efficiency and reliability of products. Compared with conventional plasma, flame, and high-velocity oxy-fuel spraying thermal-sprayed coatings, induction-fused coatings provide a far stronger metallurgical bond at the interface, while minimizing the inclusion of pores. In addition, the tubes are less costly than those with welded coatings, and the process reduces the distortion of the products, facilitating easier final assembly. A successful experimental application of 11 units in a waste incinerator revealed virtually no corrosion on the exposed surfaces, and showed an improved water heating efficiency over that of the original tubes. Such units are now being employed in four incinerators in Taiwan, and continuing tests are showing great promise.     

Evaluation of different coating systems by electrochemical methods

Corrosion protection of organic coated steel is determined by free corrosion potential measurements and impedance spectroscopy. The results are classified by means of very basic considerations and evaluation figures are developed. These electrochemical data are correlated with the extent of the corrosion for each coating system. The evaluation figures are used for ranking coating systems and this ranking is correlated with the ranking with reference to the results of standardized and exposure tests.     

Preparation of micro-arc oxidation coatings on magnesium alloy and its thermal shock resistance property

1. Introduction Due to their high specific strength, good electro-magnetic shielding characteristics, high damping characteristics, good cast ability, and excellent pol-ishing capability, magnesium alloys are extensively used in aeronautical, automobile, and electro- communication industries [1-3]. But magnesium has some disadvantages, such as low chemical stability, high negative electric potential, and low hardness, so it is necessary to use surface disposal to accommo-date the demand for re…     

用微量元素涂料改善球铁件热节组织的试验研究

对RE、Tc、Bi、Sb等微量元素以涂料形式对球铁件厚大热节部位进行微合金化,以改善其组织的可能性进行了试验研究,结果表明:多元微量元素涂料可有效地消除碎块状石墨,提高球化率,改善球铁组织,涂料层厚度影响微合金化程度而应严格控制,该工艺具有简便。无炉料污染、可代替冷铁以确保复杂铸件组织均一等优点。     

电流密度对声电沉积生物活性透钙磷石涂层结构和形貌的影响

通过声电沉积工艺在碳／碳复合材料表面制备了生物活性透钙磷石涂层，采用SEM、FFIR、XRD研究了超声场中电流密度对涂层组成结构和形貌的影响。发现在一定工艺条件下，随电流密度增加，涂层的平均晶粒尺寸减小，致密度增加；当电流密度小于l0mA／cm^2时涂层形貌为片状，l0mA／cm^2-26mA／cm^2时为粒状，32mA／cm^2时为花菜心状。且涂层中透钙磷石晶体的择优取向也发生变化，择优晶面依次为(021)、(111)、(220)。同时还讨论了涂层微观结构变化机理。     

Structure and Properties Characterization of Ceramic Coatings Produced on Steel Using a Combined Technique

STEEL is the most widely used material in engineering,but unfortunately,steel exhibits poor wear resistanceand obvious contact corrosion.For decades,researchersprepared coatings on steel to improve its properties;ceramic is one of these coatings.To obtain ceramiccoatings on steel,many researchers use techniques suchas plasma spraying,laser cladding,etc.,but some ofthem are too expensive,some of them have a deep heataffected zone in the substrate,and some of them cannot bond well with the subs…     

����ʽ��������ŵ���������մɲ��֯֯�������о�

 在大量科学试验基础上，提出一种金属表面形成金属陶瓷的新工艺方法。该方法具有放电电压低，陶瓷层结构致密与基体冶金结合，适用于多种金属材料等优点。文中利用光学显微镜和扫描电镜（SEM）观察了陶瓷涂层的显微组织，并通过X射线衍射和机械性能试验对其相结构和室温力学性能进行了探讨。结果表明：金属陶瓷涂层的晶粒细小，分布均匀，具有高的硬度及良好的耐磨性。