Performance, coating protective

As water penetrates through the coating, slight hydrolysis of zinc phosphate occurs, resulting in secondary phosphate ions. These phosphate ions in turn form a protective passive layer [53,54] that, when sufficiently thick, prevents anodic corrosion [55]. Porosity of the phosphate coatings is closely related to the coating protective performance [37]. The approximate formula for the phosphatized metallic compound is ... 

Tanl . Coatings for Hquid cargo tanks ate selected according to the materials that the tanks (qv) ate to contain. Tank coatings protect the cargo from contamination and must be compatible with the material carried. Epoxy systems ate most frequendy selected because they perform well with both aqueous and organic products. A carefully appHed three-coat epoxy system having a dry-film thickness of 225—300 pm can be expected to last for 12 years. 

An arrest in a corrosion process, after some period involving insignificant metal loss was observed, evidenced the formation of a protective interface film. The characterisation of the film showed that its properties were in accord with the recognised protective performance of the coating system. 

Salt spray test. The model coatings of Table I are of the high solid type used in automotive top coats. Their primary function is not corrosion protection since this is first of all a matter of phosphate layer, electrocoat and/or primer. However, the topcoats may contribute to corrosion protection by their barrier function for water, oxygen and salts. Therefore their permeability is important as one of the factors in the corrosion protection by the total coating system. We feel that a salt spray test of the model coatings directly applied to a steel surface is of little relevance for their corrosion protection performance in a real system. 

Electrochemical impedance spectroscopy (EIS) is a valuable method with which to study the barrier property and corrosion protection performance of polymer-coated metals it has been widely used in this field in recent years [11-15]. Many examples can be found in the literature, which illustrate the performance deterioration of different coatings on metals as well as pretreatment effects on the properties of... 

The overall corrosion protection of a metal, as well as general protective coatings irrespective of their function of coating, depends on the performance of a system as a whole, including its many interfaces and coating layers. These factors are not only mutually dependent as a combination but also in the order of application (permutation). Any single factor cannot be treated as a dominant one. There is very little work in the literature that focuses on the role of interfacial factors in the corrosion protection performance of coated systems. 

An ideal model system was selected to study the interfacial factors with EIS [19]. The model system was Parylene C-coated Alclad (aluminum-clad aluminum alloy). In this system, the surface state of the top surface (salt solution/coating interface) and the adhesion of the coating (coating/metal interface) were modified to study the influence of these factors on the corrosion protection performance of the system. 

E-coat stripping. Both plasma-treated panels show excellent corrosion protection performance as compared to the control panels. All [2A] panels with different plasma treatments and plasma polymer coatings, which were corrosion tested in both SO2 and Prohesion salt spray tests, were similarly scanned, and the corrosion width was evaluated by using a scanned image and computer calculation of the corroded area. Figure 31.19 compares the corrosion width obtained by the two methods. 

It should be emphasized that the primers in the plasma coating systems applied to the IVD Al-coated A1 alloys could not be removed by the commercial Turco paint stripper solution. This tenacious and water-insensitive adhesion at the primer/IVD interface achieved by TMS cathodic polymerization in a closed reactor system must be responsible for the excellent corrosion protection performance of these plasma coating systems. In other words, excellent corrosion protection of IVD Al-coated A1 alloys can be accomplished with chromate-free primer coatings with the aid of tenacious and water-insensitive interface adhesion. 

Nuclear coatings are formulated to seal and protect concrete, concrete block and steel surfaces. The most commonly used coating types are the amine and polyamide cured epoxy systems. The solids, by volume, can vary from 50 to 100% with fillers or reinforcement fibers usually added so that the coating can perform a wide variety of functions. Reasons for their wide use are that they bond tenaciously to a variety of substrates they cure to a hard smooth finish which results in superior decontamination qualities and, most importantly, they perform satisfactorily in Ciass 1 and 2 service. 

Romm, F., Karchevsky V., and Figovsky L. Optimal Fire Tests of Protective Coatings, Materials Performance no. 1 (2002) 44-47. 

This paper wiU build on previous reviews which have sought to explore the marmer in which surface analysis methods can be purposefully employed to understand adhesion phenomena [4—6], with an emphasis on the elucidation of interphase chemistry. The rationale behind such an approach is that it is this critical region of a polymer/metal or polymer/polymer couple that will influence the performance of the overall system, be it the durability of an adhesive joint or the corrosion protection performance of an organic coating. 

The corrosion protection performance of the sol-gel films was estimated by accelerated test using immersion in a NaCl solution. Fig. 2 demonstrates the coated surface after the immersion tests. The reference sample prepared without titania nanoparticles is strongly attacked after 10 days in 0.05 M NaCl. In contrast, the sample with titania nanoparticles seems almost untouched even after one month in concentrated NaCl solution. 

EIS measures the response of corrosion systems to ac perturbations. It has been used in corrosion research to estimate the corrosion rates and to study the passivation of metals, the corrosion protection provided by inhibitors, sacrificial and barrier properties of elec-trodeposited coatings, and performance of polymer coatings such as paints. EIS only... 

U. Riaz, S. Ahmad, and S. M. Ashraf, Comparison of corrosion protective performance of nanostructured polyaniline and poly(l-naphthylamine)-based alkyd coatings on mild steel. Mater. Corn, 60, 280-286 (2009). 

Electrodeposition of PANI derivatives was achieved by Shah and Iroh [108] in the case of Al alloy (2024) and N-ethylaniline in aqueous oxalic acid solution. The coating was electrodeposited by cyclic voltammetry by application of an unusually large potential range (-1V to -I-3V/SCE). Corrosion current was measured in chloride solutions from Tafel plots and was found to be significantly lower (about one order of magnitude) than that of bare Al-2024. Multifunctional coatings (PPy/PANI) were also achieved on aluminium by coelectropolymerization of aniline and pyrrole (in a feed ratio of 3 7) in oxalic acid solution, but protection performances were not given [109,110]. 

The salt water immersion test (SWI) and the standard salt spray (fog) test (SS) were conducted for both ISPCs and control baking enamels applied on bare CRS, iron phosphated B-1000, and BD+P60 panels. The painted coupons of about 1.0 mil dry film thickness cured at 163 C for 15 minutes were X-cut through the film to the substrate and then either immersed in a 3% NaCI solution (SWI test) or subjected to a continuous salt-solution spray in a test chamber (SS test). After a specified duration of testing, the specimens were removed from the salt solution, and the coated surface was immediately dried. A DUCK brand tape (Manco, Inc., Westlake, OH) was applied over the X-cut and then removed, and the protective performance was... 

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