船用涂料的检测及所存在的局限性

简要介绍了我国船用涂料的检验标准和船检的认可程序,通过对多种船用涂料的性能检测,发现现采用的船用涂料国家标准存在一定的局限性和不适应性;对一些存在缺陷的指标进一步进行了分析,提出了一些合理化的建议,以督促有关部门对现有的标准进行修改,适应和满足我国船舶涂料发展的需要。     

Degradation modes of crosslinked coatings exposed to photolytic environment

The objective of this study is to assess the degradation modes of crosslinked coatings exposed to photolytic environments. Three model crosslinked coatings were exposed in various ultraviolet environments. Atomic force microscopy and Fourier transform infrared spectroscopy were used in following nanoscale physical and chemical degradation during exposures. Results indicated that photodegradation of crosslinked coatings is a spatially localized (inhomogeneous) process in which nanometer-sized pits are initially formed; these pits deepen and enlarge with exposure. A conceptual model is proposed to explain the inhomogeneous degradation mode. The model proposes that nanosize “hydrophilic” domains are dispersed randomly with the highly crosslinked units. These hydrophilic domains, which are energetically preferred, comprise polar, unreacted and partially polymerized molecules, chromophores, and other additives. Photodegradation initiates at degradation-susceptible hydrophilic domains spreading to surrounding areas contiguous with the initiation site.     

Comprehensive understanding of horizontal and vertical crack effects on failure mechanism of lamellar structured thermal barrier coatings

The local spalling induced by the propagation and coalescence of cracks in the ceramic layer is the fundamental reason for the thermal barrier coatings (TBCs) failure. To clarify the effects of horizontal and vertical cracks on the coating failure, an integrated model combining dynamic TGO growth and ceramic sintering is developed. The effects of cracks on the normal and shear stress characteristics are analyzed. The driving force and propagation ability of cracks under different configurations are evaluated. The interaction between horizontal and vertical cracks is explored by analyzing the variation of the crack driving force. The results show that TGO growth causes the ratcheting increase of σ₂₂ tensile stress above the valley, and the σ₁₂ shear stress is on both sides of the peak. Ceramic sintering mainly contributes to the ratcheting increase of σ₁₁ tensile stress. There is minimum strain energy when the horizontal crack extends to the peak. The vertical cracks on the surface of the ceramic layer are easier to propagate through the coating than that of other locations. When the horizontal and vertical cracks simultaneously appear near the valley, they can promote the propagation of each other. The present results can offer theoretical support for the design of an advanced TBC system in the future.     

A proposed model for accelerated-stress life-test data exhibiting two failure modes

Accelerated-stress life-testing involves testing of a material or system at a series of stresses higher than that which is normally seen in service. An estimate of the service life is then obtained by extrapolating the failure time vs stress relationship to use stress. A common problem with this methodology is that a change in failure mechanism may occur if stresses become too high. When this occurs, the data above and below the failure mode transition point are generally treated separately. This paper discusses a model that allows for a change in failure mechanism and characterizes the transition by a probability density function over stress. Advantages of the model are: it allows representation of all test data by a single equation; it allows probability statements to be made about the probability of failure of either failure mode; it allows optimal experiments to be designed; and it allows data in the area of the failure mode transition to contribute to the precision of the estimated service life.     

Strength and failure modes of ceramic multilayers

A model was developed for the prediction of the tensile strength of thin, symmetric 3-layer sandwich specimens. The model predictions rationalize the effect of heat-treatment temperature on the strength of sandwich specimens consisting of an YSZ (Yttria-Stabilized Zirconia) substrate coated with porous NiO-YSZ layers. The model accounts for two different failure modes. Coated YSZ specimens heat-treated below 1200 °C were predicted to fail from flaws in the substrate while specimens heat-treated at higher temperatures were predicted to fail from channeling cracks forming in the coating and propagating into the substrate. These predictions are consistent with microstructural observations of the fracture surfaces. A good agreement was found between the measured strength values and model predictions.     

纳米技术在表面覆盖层中的应用

介绍了纳米技术在涂料和电镀中的应用。纳米技术可以改善涂料性能，增强其硬度、抗氧化性，使其具有光催化、抗菌、吸收电磁波、随角度变色以及对水、油的亲疏性能。介绍了制备纳米镀层的电沉积方法，主要有直流电沉积、脉冲电沉积和复合共沉积。纳米覆盖层广泛应用在工业、环境、医药、军事及科技领域中，应用前景宽广。     

The effect of cataphoretic and powder coatings on the strength and failure modes of EN AW-5754 aluminium alloy adhesive joints

The aim of this study is to determine the effect of cataphoretic and powder coatings and also the method of application the primer on the adherends surface on the strength and failure modes of EN AW-5754 aluminium alloy adhesive joints. The study is performed on lap joints made of EN AW-5754 aluminium alloy, subjected to three different types of surface treatment; namely a) polyurethane cataphoretic coating, b) powder coating based on black mat RAL 9005 UL polyester resin and c) no coating. The tested adhesive joints were made using a one-component polyurethane adhesive Terostat 8596, which was dedicated for automotive and cured under a constant load of 0.018 MPa at 20 ± 2 °C. In addition, this study investigates the effect of the application of Terostat 8519P adhesion promoter which is a liquid polyurethane-based primer containing solvents and which is corresponding to Terostat 8596 polyurethane adhesive. Terostat 8519P adhesion promoter was applied in two different ways: a) to one substrate and b) to both substrates. The produced adhesive joints were subjected to strength tests using the Zwick/Roell Z150 testing machine. The examination of fracture in the tested adhesive joints was performed in accordance with the EN ISO 10365 standard. The shear strength results have demonstrated that both the method of application of the adhesion promoter (Terostat 8519 P) and the presence of cataphoretic coating had an influence on adhesive joints strength. The use of the adhesion promoter significantly affects the strength of both uncoated EN AW-5754 aluminium alloy adhesive joints and the adhesive joints subjected to powder coating. The use of the adhesion promoter has a less significant effect on the cataphoretic-coated samples.     

聚氨酯涂料研究现状及发展

聚氨酯是世界六大具有发展前途的合成材料之一,聚氨酯涂料具有良好的粘结性、耐磨擦性,光泽度高,是涂料行业中占有非常重要的位置的主要品种之一。综述了聚氨酯涂料用单体、预聚物和环保型聚氨酯涂料的研究进展,介绍了环保型聚氨酯涂料性能与应用,指出了聚氨酯涂料的发展趋势。     

木器涂料的现状及发展趋势

简要回顾我国木器涂料的发展沿革 ,介绍国外部分国家和地区的市场状况以及国内主要生产商的区域分布。对今后的发展趋势作了探讨。     

Failure modes in organic coatings studied by scanning acoustic microscopy

Scanning acoustic microscopy (SAM) has been found to be well suited to study physically and chemically induced changes and defects in polymer coatings exposed to corrosive environments. In this work, SAM was used to investigate sub-surface migration and blister formation in polymer coatings of different layer structure after exposure to a corrosive solution. Two model systems consisting of base coat and clear coat on steel substrates where studied. The time evolution of sub-surface migration fronts and blister initiation and their growth were investigated by analysing SAM images after different exposure times. Depending on the layer structure, it was possible to differentiate between transport of the electrolyte solution (i) through the coating and (ii) along the coating/substrate interface. Samples without clear coat typically showed randomly distributed blisters at the coating/substrate interface, irrespective of the location of initial defects. The random distribution of blisters is related to diffusion of the electrolyte solution through the coating layer followed by “nucleation” at weak spots of the substrate, at the interface between polymer and substrate or within the polymer. In contrast, samples with a clear coat acting as a diffusion barrier showed a sub-surface migration front of 2–4 μm height, propagating along the coating/substrate interface, starting at initial defects. The linear propagation of this front cannot be explained by Fickian diffusion and is discussed in terms of an accelerated diffusion or crack growth kinetics. Since blistering started only at regions, where the migration front has already passed, the presence of electrolyte solution or water at the coating/substrate interface was found to be a prerequisite for the nucleation of blisters.     

环保型涂料在美国家具企业中的应用

家具生产过程产生大量的挥发性有机化合物(VOC)和有害大气污染物(HAP),对环境造成严重的影响,而生产过程使用的涂料和胶黏剂是这些污染物的来源。论文概述了国内家具生产主要工序及其产生废弃物的状况,介绍了美国Ethan Allen公司、Knoll公司、Geiger Brickel公司和Hussey Seating公司分别以高固体分涂料、粉末涂料、水性涂料和辐射固化涂料取代传统涂料的清洁生产方案以及取得的环境和经济效益,为我国家具企业开展清洁生产提供参考。     

氨基树脂涂料的现状与发展

氨基树脂涂料在世界及我国涂料工业中都占着主体品种的地位，本文简介了其组成、性能、用途及其新产品的开发，并对我国涂料工业骨干企业生产、开发氨基树脂的情况作了概述。     

膨胀型饰面防火涂料现状及进展

简要介绍了膨胀型饰面防火涂料的阻燃原理和分类。阐述了我国饰面型防火涂料的发展现状及最新科研成果,比较国内外饰面型防火涂料的标准,同时对国内新旧标准的变化进行简要的比较。最后,对我国膨胀型饰面防火涂料的发展趋势进行了展望。     

Interfacial adhesion and failure modes in single filament thermoplastic composites

The single filament composite (SFC) test has been uses to investigate the adhesion of carbon and glass fibers to thermoplastic matrices. A new modification of the test is proposed, consisting of SFC specimens stretched until the neck formation is complete. This makes the measuring of fiber fragment lengths much easier and allows a wider class of matrices to be investigated. The adhesion between fiber and thermoplastic matrix is strongly dependent on the contact forming conditions. With increased time of thermal treatment, interfacial bonding is improved and the failuere mode is changed. In the case of por fiber-mitrix adhesion, interfacial failure occurs. With an increase in interfacial shear strength, the martix cracks perpendicular to the fiber at the fiber breaks.     

稀土氧化物在陶瓷涂层中的应用

综述了稀土氧化物在陶瓷涂层中的应用状况,论述了稀土氧化物对陶瓷涂层的力学性能、抗热震性能、耐磨性和耐蚀性的影响,认为稀土氧化物对陶瓷涂层的改性作用主要表现在细化晶粒、净化组织、产生固溶强化和弥散强化等方面。     

硅烷在油漆与涂料中的应用

介绍了硅烷在涂料中的各种最新应用,包括各种硅烷改性水性丙烯酸酯涂料、硅烷增粘底漆、硅烷溶胶-凝胶涂料及硅烷富锌底漆等。对涂料工程师在各种涂料配方中应用硅烷来提高涂料性能具有一定的借鉴作用。     

脱气剂在透气型粉末涂料中的应用

介绍了一种可掩盖底材缺陷的透气型粉末涂料配方。比较了5种脱气剂的脱气效果。结果发现,主要成分为聚乙烯蜡的脱气剂MPP230与MPP620可以明显改善热浸镀锌件涂装存在的问题。     

高分散性纳米氧化锆晶粒在涂料中的应用

利用非水合成方法得到的高分散性纳米氧化锆(zrO2)晶粒为原料,经甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)改性后,与紫外光固化涂料混合,荻得纳米复合涂料.实验发现,纳米复合涂层存在从透明性向不透明性转变的临界ZrO2浓度,此浓度值强烈依赖于有机相的组成和MPS在纳米ZrO2粒子表面的接枝量.在ZrO2临界浓度以下,纳米复合涂层的折射率,显微硬度、热稳定性随着纳米ZrO2用量的增加而提高;但ZrO2浓度高时,由于双键转化率的降低以及有机相-无机相之间界面作用力的减小,其各项性能开始明显恶化.