Comparison of drag characteristics of self-polishing co-polymers and silicone foul release coatings: A study of wettability and surface roughness

An experimental study has been carried out to evaluate the drag characteristics of different self-polishing co-polymers (SPC) (tin based and tin-free) and a silicone foul release (FR) coating. Drag measurements have been performed on a smooth aluminum cylinder connected to a rotor device. Various coatings on cylinders were examined and differential length technique was also used to avoid the end effects during rotation. Surface energy of the coated samples was determined using static contact angle measurement. Characteristic roughness measurements of the coated surfaces were evaluated with atomic force microscopy (AFM) technique.Drag measurements showed that the frictional resistance of the FR coated cylinders was lower than that of SPC coated samples.Contact angle results showed that the critical surface tension and its polar component for silicone FR coating are less than SPC coatings. This prevents firm adhesion of fouling organisms on underwater hulls.AFM studies revealed a lower surface roughness for silicone FR coating as compared to SPC coatings. Also, its surface texture is considerably different from SPC coatings.It can be concluded that the drag characteristics of a surface are affected by its free energy and roughness parameters.     

Preparation,thermal properties and permeabilities of aluminum-coated fabrics destined for thermal radiation protective clothing

In this study, radiant reflective, flame retardant and water vapor permeable coatings were fabricated on aramid fabric (AF) for thermal radiation protective clothing by using a simple cost-effective coating method, which included an aluminum paste, APP-PER-MEL and a silk fibroin powder in the TPU solution system. The permeability, flame retardancy, thermal stability, radiative spectral reflectance, as well as RPP of these prepared fabrics were characterized and compared with the pure AF and aluminum-foiled AF (AF-AF). Results show that the newly developed aluminized AF had rather high permeability, and the permeable capability would be further enhanced with the additive of silk fibroin powder. The flame retardancy (FR) of the coated fabric sample was also achieved by introducing an intumescent FR system. In contrast to the pure AF, the aluminum-coated AF provided higher levels of radiation protection in RPP testing. This was further confirmed by the fact that aluminum-coated AF exhibited comparative high average reflectivities (more than 0.7) in the radiant spectral range of 1547 nm to 2500 nm. Thus, the aluminum-coated AF prepared by functional coating method exhibit great and competitive practicability in thermal protective clothing due to their excellent moisture comfort and radiant thermal protection.     

Comparison of drag characteristics of self-polishing co-polymers and silicone foul release coatings: A study of wettability and surface roughness

An experimental study has been carried out to evaluate the drag characteristics of different self-polishing co-polymers (SPC) (tin based and tin-free) and a silicone foul release (FR) coating. Drag measurements have been performed on a smooth aluminum cylinder connected to a rotor device. Various coatings on cylinders were examined and differential length technique was also used to avoid the end effects during rotation. Surface energy of the coated samples was determined using static contact angle measurement. Characteristic roughness measurements of the coated surfaces were evaluated with atomic force microscopy (AFM) technique.

Drag measurements showed that the frictional resistance of the FR coated cylinders was lower than that of SPC coated samples.

Contact angle results showed that the critical surface tension and its polar component for silicone FR coating are less than SPC coatings. This prevents firm adhesion of fouling organisms on underwater hulls.

AFM studies revealed a lower surface roughness for silicone FR coating as compared to SPC coatings. Also, its surface texture is considerably different from SPC coatings.

It can be concluded that the drag characteristics of a surface are affected by its free energy and roughness parameters.     

High-Throughput Screening of Fouling-Release Properties: An Overview

Marine biofouling of ship hulls has significant cost, performance and environmental implications. Due to environmental concerns associated with traditional antifouling paints that mitigate fouling with the use of biocides, increasing research and development efforts have been made on fouling-release (FR) coatings. FR coatings do not actively deter settlement of marine organisms, but, instead, mitigate biofouling by minimizing the strength of adhesion. Ideally, an FR coating will allow the fouling community to be removed by simply running the vessel at relatively high speed. Traditional methods for characterizing FR properties involve immersion of relatively large samples in the ocean and waiting months for enough fouling to occur to enable reliable measurements to be made. To greatly enhance research and development relative to FR coatings, a combinatorial/high-throughput workflow was developed that includes a suite of FR laboratory assays involving marine bacteria, microalgae, and live, adult barnacles. The novel high-throughput FR measurement systems have been shown to allow for rapid screening of FR characteristics of miniaturized coating samples arranged in an array format.     

钛制压力容器的焊缝应力研究

通过试验证明钛容器的破坏都是从焊缝开始的，其焊缝应力以离焊根５～１０ｍｍ处最大，达到了筒体按双向强化计算值２．２８～３．５１倍，并在此基础上提出了加强钛容器焊缝强度研究和如何降低焊缝应力峰值研究的新课题     

Tara tannin a natural product with antifouling coating application

The international trade by marine transportation has increased continuously since the 70s. The undesirable accumulation of a wide variety of marine organisms (biofouling) on ship hulls can lead to significant increased costs, principally by increased fuel consumption. On the other hand, there is a great concern about the biocides commonly used in commercial antifouling (AF) protective systems due to the high concentration encountered in coastal areas and the potential damage they could cause to marine organisms. As a consequence, the development of alternative AF coatings with new natural products as biocides inhibit is a key factor. In this approach, tara tannin (TT) is being proposed as a promising solution. It is important to note that TT is obtained from the pods of the tree avoiding its cutting down. The aim of this research was, primarily, to explore the possible application of a natural and abundant product, such as the TT, in the preparation of AF coatings. So, a TT derivative was obtained and characterized to be employed as the bioactive compound in AF coatings. Previous to the immersion in natural environments, the dissolution of TT from AF coating in artificial sea water (ASW) was studied. TT was incorporated into the coating as zinc “tannate”. One of the tested coatings proved to be efficient in AF protection in natural sea water (NSW) at Mar del Plata (38°08′17″S–57°31′18″W) harbor during eight months. The addition of 2% by weight of zinc oxide to the coating extended its service life until the year.     

Effect of welding parameters on the heat affected zone and the mechanical properties of friction stir welded poly(ethylene-terephthalate-glycol)

The bond strength and the heat affected zone (HAZ) of friction stir welded seams made of poly(ethylene-terephthalate-glycol) are analyzed in the article. The seams were prepared with various settings (rotation speed and feeding rate) and with various welding tools. Using the welding parameters (rotation speed, the feed rate, and the tool diameter) a K-factor characterizing the welding process was defined. The novel K factor is related to the welding heat input, which is in direct correlation with both the range of the HAZ and the mechanical properties of the seam. The HAZ formed was analyzed by stress optical method, the mechanical properties by flexural test. It has been demonstrated that the efficiency factor of the welded joint is closely related to the width of the HAZ and it depends on the welding parameters and the tools. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

化学镀镍316不锈钢激光焊接裂纹研究

通过调整镀液中磷酸钠的质量浓度,在316不锈钢表面化学镀得到P质量分数分别为1.2%、2.3%和3.4%的镍镀层。对镀镍316不锈钢进行激光焊接实验,得到较佳的工艺参数为:激光功率50 W,脉冲宽度60 ns,焊接速率200 mm/s。当镀层中磷的质量分数为1.2%时,焊缝中无裂纹,剪切强度为242 MPa。随镀层中磷质量分数的增大,焊缝中的裂纹增多,焊缝的剪切强度逐渐降低。     

压力容器焊缝及其结构设计

压力容器破裂的主要原因是焊接质量低劣，指出了影响焊缝质量的因素，论述了焊缝结构设计基础及焊缝设计应注意的问题     

氧化反应器汽包壁焊缝区的腐蚀与防护

介绍了碳钢汽包壁焊缝与不锈钢加强板在１４５～１６０℃高温的弱酸性工业循环水中的电偶腐蚀情况,对腐蚀的原因及腐蚀机理进行了分析,并对焊缝区实施了牺牲阳极阴极保护。经生产运行验证,取得了满意效果。     

The relationship between welding temperature and T-peel strength of heat-welded seams in single-ply roof-coverings

The results of studying the parameters influencing the quality of watertight seams in single-ply roof-coverings for flat and low-sloped roofs during heat-welding are summarized in this paper. Seam samples of four different single-ply roof-covering products, i.e. atactic polypropylene (APP)-modified bitumen, styrene-butadiene-styrene copolymer (SBS)-modified bitumen, ethylene-copolymerized bitumen (ECB), and plasticized polyvinyl chloride (PVC), were prepared by welding at various hot-air temperatures and speeds. The seam strengths of the specimens cut off from the heat-welded samples were measured by the T-peel test. The results were supplemented by observation of fracture propagation during the test. The T-peel strength of heat-welded seams is correlated to the hot-air temperature and welding speed. For the bituminous products, there is a limitation to the hot-air temperature at which the seam will attain an acceptable T-peel strength. For the thermoplastic products, the welding speed is more significant in producing sufficiently strong watertight seams by heat-welding.     

Performance of polyurethane-coated concrete in sewer environment

Polyurethane-based coatings are used to protect concrete facilities against corrosive environments. The performances of two commercially available polyurethane coatings were evaluated under sulfuric acid environment (representing sewer condition) for over 5 years. Both dry (representing new construction) and wet (representing rehabilitation) concretes were used in this study. A combination of the full-scale hydrostatic test, bonding test, and chemical resistance tests were performed to evaluate the coatings to protect concrete structures below ground water. The full-scale hydrostatic test was used to evaluate the application and performance of coatings under hydrostatic pressure to simulate underground concrete structures below ground water. Visual inspections and in situ bonding tests were performed on coated concrete under a hydrostatic pressure of 105 kPa. Test results showed that bonding strength of one coating was affected by the moisture condition and hydrostatic water pressure in the full-scale test. Coated cement concrete specimens with pinholes were used to study the chemical resistance of the coated concrete in sulfuric acid to represent the worst sewer condition. Change in weight of coated concrete specimens was measured at regular intervals. Types of failures in coated concrete under acidic environment have been identified. Test results showed that the performance of the two coatings were noticeably different and one coating with pinholes extended the service life of concrete by 14 times while the other coating extended the service life of concrete by 57 times. There was no direct correlation between bonding strength and chemical resistance of the polyurethane-coated concrete. Although both coatings were polyurethane-based, their performances were different under the testing conditions adopted in the study.     

Effects of pigmentation on siloxane–polyurethane coatings and their performance as fouling-release marine coatings

Siloxane–polyurethane paints were formulated and characterized for coating properties and performance as fouling-release (FR) marine coatings. Paints were formulated at 20 and 30 pigment volume concentrations with titanium dioxide, and aminopropyl-terminated poly(dimethylsiloxane) (APT-PDMS) loadings were varied from 0 to 30% based on binder mass. The coatings were characterized for water contact angle, surface energy (SE), gloss, and pseudobarnacle (PB) adhesion. The assessment of the FR performance compared with polyurethane (PU) and silicone standards through the use of laboratory biological assays was also performed. Biofilm retention and adhesion were conducted with the marine bacterium Cellulophaga lytica, and the microalgae diatom Navicula incerta. Live adult barnacle reattachment using Amphibalanus amphitrite was also performed. The pigmented coatings were found to have properties and FR performance similar to those prepared without pigment. However, a higher loading of PDMS was required, in some cases, to obtain the same properties as coatings prepared without pigment. These coatings rely on a self-stratification mechanism to bring the PDMS to the coating surface. The slight reduction in water contact angle (WCA) and increase in pseudobarnacle release force with pigmentation suggests that pigmentation slowed or interfered with the self-stratification mechanism. However, increasing the PDMS loading is an apparent method for overcoming this issue, allowing for coatings having similar properties as those of clear coatings and FR performance similar to those of silicone standard coatings.     

Synthesis,characterization, and evaluation of antifouling polymers of 4‐acryloyloxybenzaldehyde with methyl methacrylate

In recent years, antifouling (AF) polymers are widely used in marine paints to protect the ship hulls from biofouling. The AF polymer coatings have better leaching characteristics and long lasting efficiency than other conventional formulations. In this study, an attempt has been made to prepare new p‐acryloyloxybenzaldehyde(AcBA) polymers to assess their AF efficiency against marine microfoulers. The monomer, AcBA was prepared by the esterification reaction between p‐hydroxybenzaldehyde (HBA) and acryloyl chloride (Ac) in presence of triethylamine (TEA) in MEK at 0°C. The reaction was monitored by TLC and the prepared monomer was characterized by UV, IR, ¹H‐NMR and GC‐MS. The homo‐[poly(AcBA)] and co‐polymers [poly(AcBA‐co‐MMA)] were prepared by solution polymerization using BPO as initiator. To find out the AF activity of prepared polymers, representatives of marine microfoulers, shipfouling bacteria (Bacillus macroides and Pseudomonas aeruginosa) and microalgae (Amphora coffeaeformis and Navicula incerta) were screened. The contact toxicity and diatom attachment assays were conducted with prepared polymers and microfouling formation on coatings was also investigated using a tubular biofilm reactor. AF potential of these polymers coating is demonstrated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

舰船新型涂料的研究进展

介绍了新型船舶涂料的种类。综述了船舶用防污涂料、船体防锈涂料和舰用特种功能涂料包括吸波涂料、纳米隐身涂料和其它新型涂料(防滑涂层、潜艇特征信号控制涂层、新型光触媒涂料、新型室温可逆变色涂料、新型热防护涂料、热障涂层和溶胶-凝胶涂层等)的性能和研究状况。指出了其发展趋势。     

压力容器焊缝抽样探伤的概率分析

本文用概率论计算方法对压力容器焊缝百分比抽样探伤检验规则进行分析。探讨了使抽检方案合理化的方法。     

表面涂层对混凝土吸水性能的影响

采用四种表面涂层,以吸水率为评价指标,研究混凝土试件涂刷表面涂层后吸水性能的变化规律。试验结果表明,表面涂层在不同程度上降低了混凝土试件吸水率,其中聚氨酯涂层效果最佳,乳胶涂层效果最差,氟碳涂层、桥梁涂层效果介于聚氨酯涂层与乳胶涂层之间。混凝土试件的吸水率随着涂层涂刷遍数的增加逐渐降低,而降低幅度在减小,根据混凝土结构所处环境,从经济性角度选择适当的涂刷遍数。空白件及涂刷涂层的混凝土试件吸水率均随着水灰比的增大而提高。     

Water transportation through organic coatings: correlation between electrochemical impedance measurements, gravimetry, and water vapor permeability

A primary cause of coating failure is diffusion of water through organic coatings during which many corrosive species are transported to the metal-coating interface. However, water vapor permeability through the coating improves blister resistance to a certain extent. The present work describes the influence of chemical nature of the polymer on the above two properties. Attempts were also made to establish a correlation between these two properties for pigmented organic coating. Six paints were formulated and processed using six different types of binders at a constant pigment volume concentration (PVC) and specific gravity. Water ingress, water vapor permeability, and water absorption of these coatings were estimated using electrochemical impedance measurements (EIS), permeability cup method, and gravimetric method, respectively. There exists a good linear correlation between water uptake measured by EIS and water absorption measured by gravimetry. Similarly, a correlation was also noticed between water uptake by EIS and water vapor permeability. However, polyurethane type polymers did not fit into this linear correlation. Furthermore, influence of the resin chemistry on anticorrosive properties of these coatings was also studied using EIS and salt spray exposure test. Among all polymers under investigation, acrylic polyol-based polyurethane has shown the lowest water uptake, higher impedance, better salt spray resistance but higher water vapor transmission rate.     

An investigation of scratch testing of silicone elastomer coatings with a thickness gradient

Silicone elastomer coatings are currently being investigated as foul release coatings on ships hulls. Previous tests on silicone duplex elastomer coatings used a progressive load scratch test. It has been shown that the durability of uniform silicone duplex elastomer coatings is a function of thickness, indentation modulus, and stylus and that the failure mechanism depended on coating thickness and stylus. When applying silicone coatings to a ship's hull, there are regions on the ship where the coating is not uniform. This article investigates the effect of a thickness gradient on the durability of a single layer silicone elastomer coating. In these tests, a constant normal load was used as the stylus moved transversely to the surface. It was found that when the scratch test started in the silicone coating and proceeded in the direction of decreasing coating thickness (“Elastomer to Metal”), there was first a scratch tract followed by the initiation of detachment of the coating, then by gross detachment of the coating. When the scratch started on the exposed aluminum surface and proceeded into the silicone in the direction of increasing coating thickness (“Metal to Elastomer”), there was first gross detachment of the coating, followed by recovery (i.e., silicone coating is intact) and a scratch tract into the silicone. It was also found that the coefficient of friction was much higher in the silicone when the scratch test was going in the direction of decreasing coating thickness as opposed to the scratch test going in the opposite direction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

吸水性对防污涂料性能影响的研究

由于中国的许多船厂位于淡水流域,淡水浸泡对防污涂料的影响正引起人们越来越多的关注。本研究中,选取了4种基于丙烯酸硅烷技术和6种基于离子交换技术的防污涂料,比较了在海水和淡水里的吸水性能。为了便于确定成膜树脂与相应涂料吸水性能之间的相关性,将成膜树脂从涂料中分离出来进行研究。