Degradation profiles of polyester–urethane (hydroxylated polyester/diphenylmethane diisocyanate) and polyester–melamine (hydroxylated polyester/hexamethoxymethylmelamine) coatings: An accelerated weathering study

The successful material performance of coatings depends on the environmental conditions to which they are exposed. The effects of the diol structure and acetoacetylation on the weathering degradation of hydroxylated polyester (HP)/hexamethoxymethylmelamine and HP/diphenylmethane diisocyanate clear coatings were studied. The acetoacetylation of HPs led to better performance for higher application solids than the acetoacetylation of their base counterparts. Weathering degradation profiles were investigated with dynamic mechanical thermal analysis, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The structural variations of the building blocks and acetoacetylation were found to be important for enhancing the stability of coatings at higher application solids. Polyester–urethane coatings were more stable toward weathering than polyester–melamine coatings. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1069–1081, 2005     

Corrosion behavior of Fe‐Si metallic coatings added with NiCrAlY in an environment of fuel oil ashes at 700°C

Electrochemical potentiodynamic polarization curves and immersion tests for 300 h at 700°C in a furnace have been used to evaluate the corrosion resistance of Fe‐Si metallic coatings added with up to 50 wt.% of NiCrAIY. The corrosive environment was fuel oil ashes from a steam generator. The composition of fuel oil ashes includes high content of vanadium, sodium and sulfur. The results obtained show that only the addition of 20 wt.% NiCrAlY to the Fe‐Si coating improves its corrosion resistance. The behavior of all tested coatings is explained by the results obtained from the analysis of every coating using electron microscopy and energy dispersive X‐ray analysis.     

节能涂料在锅炉改造中的应用及推广

通过对节能涂料的原理分析及应用实验数据的对比，显示其较高的节能效率，并可减少炉渣和烟尘的排放量，有一定的环保效益，推广前景广阔。     

Thin films of liquid crystal fumarates and a related acrylate

Five fumarate esters and one acrylate ester have been synthesized and their properties examined. Four of them can be deposited as multilayers by evaporation in vacuo, and three of this group behave as thermotropic smectic liquid crystals. We have attempted to stabilize the homeotropic smectic phase by polymerizing the film using UV light. In two cases we have been successful and have produced films which are resistant to prolonged heating in THF. We infer that these materials are both polymerized and cross linked. They retain their regular layer structure after polymerization, a behaviour which we have demonstrated by X-ray diffraction. We have also attempted to form Langmuir-Blodgett multilayers with these compounds and in four cases have been successful.     

Mechanistic study of drying of alkyd resins using (Z,Z)- and (E,E)-3,6-nonadiene as model substances

The cobalt-catalysed autoxidative drying of alkyd resins was studied using (Z,Z)-3,6-nonadiene and (E,E)-3,6-nonadiene as model compounds. A large number of reaction products were isolated from the autoxidation mixture using HPLC and preparative size exclusion chromatography and identified with ¹H- and ¹³C-NMR. The identified compounds comprised C₉ hydroperoxides, endoperoxides, epoxides, aldehydes and ketones and some other oxidation products. Their chemical structures pointed to three different types of oxidation processes taking place. Besides the main radical autoxidation reaction, evidence was found for photo-sensitized oxidation involving singlet oxygen. Thirdly, epoxidation occurs via peracids or hydroperoxides formed as intermediates. Because of the large number of possible isomers having very similar physical properties, isolation of dimers required considerable effort. Nevertheless, two dimers were isolated and characterized. Their structures indicate crosslinking to occur by recombination of radicals as termination reaction.     

单组分常温自交联建筑乳胶涂料

综述了单组分常温自交联建筑乳胶涂料这一研究热点的进展情况.     

Effect of substrate temperature on the adhesion properties of magnetron sputtered nano-composite Si-C-N hard thin films

The adhesion and film failure studies on nano-composite SiCN thin films on silicon, glass and steel have been carried out. It was observed that both coating as well as the substrate has an influence on the adhesion of film. The films on hard substrate Si failed adhesively whereas on softer substrate, steel, cohesive failure was observed. The measured critical load was around 18 N and 24 N for SiCN film on silicon and steel substrate respectively. A decrease in critical load and interface toughness with the increase of substrate temperature during deposition for glass and steel substrate was observed.     

水性三聚氰胺树脂抗静电涂层的制备

在三聚氰胺甲醛树脂中掺杂结晶SnCl4·5H2O，增加树脂的抗静电性。制备出水性抗静电涂层，测定表面电阻，并通过红外光谱和热重差热对涂层进行表征。结果表明，三聚氰胺甲醛树脂本身不具备导电性，结晶SnCl4·5H2O的添加使三聚氰胺甲醛树脂导电性大大增加，水分的吸收有利于导电性的提高。20g40％的三聚氰胺甲醛树脂溶液中添加17．8gSnCl4·5H2O形成树脂溶液制备的涂层，在温度60℃，湿度为40％环境中干燥处理4h，涂层表面电阻率可低至1．39×10^7Ω·cm，在室温空气环境中电阻率可降低至8．80×10^6Ω·cm。     

金属构件的防腐问题

介绍了金属腐蚀造成的危害及其防腐措施。     

Phase formation in a Ni-50Cr HVOF coating

A complex, fine scale microstructure of non-equilibrium phases is obtained by HVOF deposition of Ni-50Cr alloy due to the rapid cooling experienced by the splats which make up the as-deposited coatings. XRD analyses indicated that the as-deposited coatings consisted predominantly of a single fcc γ-Ni phase. Two small peaks suggested the presence of NiO and/or NiCr₂O₄ at the limit of detection (∼ 5%). Shoulders on the main γ-Ni peaks were interpreted as evidence of a second, lower Cr content γ-Ni phase. Characterization of the oxide content of the as-deposited coatings by X-ray diffraction, image analysis of backscattered electron images, and electron probe microanalysis yielded conflicting results due to the size of the microstructural features present relative to the spatial resolution of these techniques. Due to the nature and feature size of the non-equilibrium oxide phase(s), direct measurement of the oxygen content by EPMA was found to be the most accurate technique. Heat treatment of an as-deposited coating at 650 °C in vacuum resulted in coarsening of the microstructural features, and an approach towards a mixture of equilibrium phases consisting of γ-Ni, α-Cr, and Cr₂O₃. Evidence was also seen in the XRD pattern of an intermetallic σ phase that has previously only been reported in thin films of Ni-Cr alloys.