无铬达克罗涂液的配方研究

以聚氨酯改性环氧树脂为黏结剂,制备成一种具有良好附着力和耐蚀性的无铬达克罗涂层。研究了涂液各组分和用量对涂层性能的影响。确定了无铬达克罗涂液的最佳配方。     

达克罗技术的应用及发展方向

达克罗技术被广泛地用于各种防腐领域的基材表面处理。从防腐机理、涂层特点、涂液的配制、涂覆工艺、设备及控制要素、涂层性能指标等方面,全面介绍了达克罗技术。并指出其现仍存在颜色单一、固化温度偏高、表面机械性能不足和进一步环保的问题。建议今后应朝着开发多彩达克罗涂层、中低温固化的达克罗技术、多功能及低铬或无铬达克罗涂液等方向发展。     

达克罗工艺浅析

1　概述达克罗是ｄａｃｒｏｍｅｔ的缩写和译音 ,又称达克锈、久耐锈、高克锈、锌铬膜等。达克罗技术主要用含有锌片、铬酸酐、乙醇等物质的糊状处理液浸渍或喷刷金属基体 ,经高温烘烤后 ,在金属基体表面形成一层有极佳耐蚀性的非装饰涂层。它杜绝了电镀过程中产生的酸、碱、锌、铬等重金属废水、废气的排放等污染问题 ,是当今替代电镀锌、热镀锌等表面防腐的新技术。2　达克罗涂液的组成达克罗涂液种类虽多 ,但涂液的基本组成可归纳如下 :(1)金属物 :锌、铝以及它们的混合物等 ,主要为超细片状锌、超细片状铝 ;(2 )溶剂 :惰性有机溶剂 ,如…     

无铬达克罗涂液配方及工艺条件的研究

以聚氨酯改性环氧树脂为粘结剂,制备出一种具有良好结合力和防腐性能的无铬达克罗涂层。实验确定了无铬达克罗涂液的配方及工艺条件。     

黑色达克罗工艺研究

介绍了黑色达克罗新技术的特点、涂液研制、性能试验情况,通过试验证明黑色达克罗涂层能满足我厂军民品消光和防腐蚀要求,是替代钢铁氧化、磷化、镀锌黑色钝化等工艺的良好涂层,是一种高防腐的“清洁生产技术“。     

影响锌铬涂层性能因素的研究

本文研究了影响锌铬涂层性能的几个主要因素，包括金属粉、还原剂、铬酐、涂层Cr^6＋含量和pH值对涂层性能的影响。研究表明，采用不同制备方法所得到的金属粉对涂层性能有较大的影响；涂液中还原剂、铬酐、涂层Cr^6＋含量和pH值对涂层性能都有影响。     

金属系防静电涂料导电性能的影响研究

针对金属系防静电涂料,研究了金属粉用量、粒径、种类、形状以及在空气中暴露时间对涂层导电性能的影响。采用涂料电阻率测定仪对涂层表面电阻率进行测定,采用扫描电子显微镜（SEM）、能谱仪（ EDS）对金属粉的微观形貌、元素组成进行探究。结果表明：金属系防静电涂料的导电性能与所考查因素密切相关。随着金属粉用量的增加,涂层的导电性能增强;随着金属粉粒径的减小,涂层的导电性能先增强后减弱, 400目金属粉制得的涂层导电性能最佳;金属系防静电涂料的导电性能取决于金属粉填料本体的导电性能;由树枝状、混合状、球状铜粉制得的涂层导电性能依次减弱;金属粉在空气中暴露一段时间后,所制得涂层导电性能均明显减弱。     

自润滑性达克罗涂层的研发

为了得到具有自润滑性的达克罗涂层,将不同规格的石墨粉以不同质量比掺杂在达克罗涂液中制备涂层.通过扭力测试评价涂层的自润滑性,并用数学方法分析数据.结果表明:在迭克罗涂液中掺杂适量一定规格的石墨粉,可以使涂层的扭力值达标.     

LSI制备具有SiC涂层的石墨材料及其性能研究

以鳞片石墨、氮化硼粉、氧化钇粉、氧化铝粉作为掺杂粉末,掺杂粉末与硅粉的混合粉末作为硅源,采用液相渗硅工艺在石墨基体材料表面制备SiC涂层。研究硅源中掺杂粉末含量对渗硅后石墨样品性能与结构的影响。XRD与SEM分析表明,经过1600℃渗硅处理后,硅源中的Si渗透到基体内部与碳发生原位反应生成SiC涂层,SiC涂层表面粘附硅少。当掺杂粉末总质量分数为12%时,制备的SiC涂层具有良好的抗氧化效果,材料在1300℃空气中氧化6 h失重率仅为1.39%。     

达克罗的研究现状

介绍了达克罗技术的先进性,论述了达克罗涂液的组成和各组分的功能及涂层的固化工艺,对涂膜的耐蚀机理进行了总结。指出了该技术存在的问题以及今后的研究方向。     

铝粉粉末涂料邦定工艺的研究

本工艺通过设计聚酯/环氧型粉末涂料配方,采用邦定包膜技术将涂料粉末粒子与铝粉牢固黏结,静电喷涂试验表明该粉末涂料高度接近电镀铬效果,可作为电镀铬的替代产品.其中铝粉与粉末粒子良好粘结,铝粉使用量可降低30％;采用静电喷涂时,对不同金属元器件粘附良好,200℃固化10分钟,其涂膜拥有类似铬电镀的高光泽度金属效果,且色泽均一.相比溶剂型涂料60 ％～65％的成膜率,该粉末涂料成膜率接近100％,且未附着于被喷涂物件的粉末可以全部回收再利用.现有的邦定包膜技术具有高效环保、低成本等特点.     

达克罗处理技术的现状与发展

达克罗涂层由于具有优良的耐蚀性,无氢脆,无污染等特点而得到广泛应用。本文阐述了达克罗处理的分类,组成,工艺特点及膜层性能。此外,介绍了达克罗技术在国内的研究及应用情况,并提出了今后的研究重点。     

铝粉对红棕色降温涂料性能的影响

有较高反射率的金属是热隐身涂料最常用和最重要的颜料种类.在实际应用中,多选用性能优异、价格低廉的铝粉.在前期实验的基础上,向3种基本组成相同而复色浆不同的红棕色涂料中加入定量的铝粉,研究了加入铝粉前、后涂层的表面发射率以及在指定波段内的反射率.结果发现,加入一定量的铝粉后,可提高涂料在380～2 500 nm波段尤其是可见光区的反射率:加入一定量的铝粉后,涂层在8.0～13.5 μm波段内的表面发射率均小于未加铝粉的涂层.     

Investigation on corrosion and wear resistance of MgO-Al2O3 composite coating prepared by plasma electrolytic oxidation

Ceramic coatings were prepared on 6061 Al alloy in a mixed electrolyte with/without MgO powders at different treatment durations. The results of energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) showed that MgO powder was incorporated into the coatings, and Mg species gradually aggregated into coating inside as prolonging the oxidation time. Scanning electron microscopy (SEM) showed that MgO additive had a certain effect on the microstructures and coating thickness. The corrosion behavior tests evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution suggested that at the same treatment time, the addition of MgO powders can improve the corrosion resistance of the coating, and the Mg-rich layer can affect the corrosion resistance of the coating. The tests of mechanical properties showed that the addition of MgO powders improved the stability and hardness of the coating.     

Anti-wear hierarchical TiC enhanced cermet coating obtained via electrical discharge coating using a reduced graphene oxide nanosheets mixed dielectric

The use of a powder mixed dielectric is one of the promising measures to overcome defects such as non-uniform thickness, voids and micro-cracks of hard coatings obtained via the electrical discharge coating (EDC) process. The quest for finding appropriate powders suspended in EDC dielectric still continues. In this paper, reduced graphene oxide nanosheets (RGONS) are explored as the additives of EDC dielectric to fabricate TiC containing composite coatings with superior tribological performance. The influences of RGONS on the surface integrity, microstructure and tribological performance of the as-prepared coatings are investigated. RGONS with lipophilic modification effectively reduce spark energy and disperse the discharges throughout the machined surface due to their uniform dispersion in the discharge gap. This allows the formation of compact coatings with banded microstructure composing of a mixture of equiaxed and columnar TiC grains within the martensite matrix. Such unique microstructure improves the as-prepared coatings’ resistance to adhesion and abrasion wear, as well as fatigue and fracture. As a result, they show obviously lower coefficient of friction and wear rate compared to the coatings obtained using a bare dielectric.     

机械镀锌-铝复合镀层的结构分析

采用金相显微镜、扫描电镜、能谱仪分析了混粉法机械镀锌-铝复合镀层的结构、形貌和化学成分分布。结果表明，机械镀锌-铝镀层主要是由尺寸不等的锌粉颗粒相互参杂、填充，形成致密结构体；锌粉颗粒之间的间隙填充着更小尺寸的锌粉和夹杂物，镀层中部分锌粉颗粒发生变形；片状铝粉在镀层中不均匀分布，铝粉和锌粉没有明显的包裹、缠绕；镀层中Fe，Sn，Zn的含量分布正常，且Al的含量比施镀前混粉中Al的含量低得多。     

Protective coatings on aluminum by spontaneous polymerization

A novel process to form protective polymer coatings on aluminum using spontaneous polymerization is described. When an aluminum sample is immersed in a partly aqueous monomer solution, polymerization proceeds rapidly on the metal surface, without the addition of initiator, at room temperature. The polymer coatings studied here were formed using styrene (St), N-phenyl maleimide (NPMI), 2-methacryloyloxy acetoacetate (MEA), and bis-maleimide (BMI), monomers, from solutions of different compositions. A possible mechanism for spontaneous initiation and propagation is proposed. The effects of process variables such as polymerization time, monomer concentration, and monomer ratios in feed on the coating thickness and properties are presented. The glass transition temperatures, adhesion strength to aluminum, thermal stability and corrosion resistance of these coatings are reported. The coatings obtained are up to 50 μm thick and conform to the shape of the substrate. They have excellent thermal stability, low dielectric constant, and show very good resistance to corrosion under the ASTM B-117 accelerated salt fog test. Other monomers and metals may also be used.     

Manufacture of Powder Coatings by Spraying of Gas‐Enriched Melts

An alternative process for the manufacture of powder coatings was developed. The continuously operated process is applicable to new (low‐melting and fast‐reacting) and conventional powder coating systems and allows to produce coatings with improved properties. The process uses the solubility of compressed gases in melts of coating polymers at pressures up to 220 bar. The single components of a powder coating mixture are melted in separated tanks and are dosed to a static mixer by means of high‐pressure pumps. In the mixer the melts are homogenized and simultaneously compressed carbon dioxide is dissolved. The so‐formed solution is depressurized directly afterwards over a nozzle into a spray tower. Thereby, the melt is atomized into fine droplets and cooled by the expanding gas. The droplets reach the solidification point of the melt and fine solid particles are formed. The particle size, particle size distribution and the morphology of the powders could be adjusted by the operating parameters of the plant.     

Impact of Al2O3-40 wt.% TiO2 feedstock powder characteristics on the sprayability,microstructure and mechanical properties of plasma sprayed coatings

Atmospheric plasma sprayed (APS) Al₂O₃-TiO₂ coatings have found a wide range of industrial application due to their favorable properties, combined with low costs and a high availability. However, the detailed effect of the phase composition and the element distribution of the feedstock powders on the coating properties and the spraying process have only crudely been investigated so far. Here the impact of aluminum titanate (Al₂TiO₅) on the microstructural features and mechanical properties of Al₂O₃-40 wt.% TiO₂ APS coatings is demonstrated by investigating the detailed phase composition and the distribution of aluminum and titanium in three fused and crushed feedstock powders and the respective coatings. Thereby, a direct influence of Al₂TiO₅ content on the deposition efficiency, the porosity, the elastic modulus, and the hardness of the coatings is revealed. The results emphasize the need for a more detailed specification of commercial Al₂O₃-TiO₂ feedstock powders to ensure a high reliability of the coating properties.