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IN many of the industrial and other aggressive environmental conditions encountered today a synthetic, plastics‐type of paint system must be used, since traditional paints give poor and limited service. However, for these synthetic paints to be fully effective, they must be applied to more scrupulously prepared surfaces. The finer tolerances and more exacting application requirements of synthetic plastics‐type coatings, such as the epoxies, must be appreciated. Once these are understood it is not difficult to put the materials into use, where they give outstanding long‐term protection. Some of the physical, chemical and solvent‐resistance characteristics of the epoxy resin coatings can, of course, be attained with other synthetic paints, and all these materials have their place in the paint manufacturer's armoury. There are resins showing better flexibility and chemical or heat resistance than the epoxies, but the latter are outstanding in combining these and other characteristics to a marked degree—hence their fairly rapid user acceptance. There is inevitably over‐lapping in characteristics with other coatings, particularly the polyurethanes, and it is not claimed here that epoxy coatings can confer protection against all corrosive environments.

HIGH SOLIDS COATINGS Review Articles Without question, the major motivation for high solids coatings is government regulations. An interesting article which summarises what the coatings industry has done in order to meet air pollution regulations in the United States has been provided by Burger (Metal Finishing, July, 1982, p. 59). His list includes, in addition to high build and solventless coatings, electrodeposition, electrostatic powder coatings, Rule 66—acceptable solvent‐based coatings, and water‐borne coatings. Air pollution results not only from solvents but from the particulates released during surface preparation. Pollution due to surface preparation has been alleviated by the use of white water sandblasting, centrifugal and rotary blast cleaning blast cleaning with carbon dioxide pellets, improved ventilation air filters and safety equipment, plasma arc and laser cleaning, sonic cleaning, special chemical cleaning, and surface preparation and vacuum blasting. In addition, solvent recovery units have been utilised extensively in industrial coatings.

This study aims to explore the synergistic effect of oxide nanoparticles (ZnO, Fe₂O₃, SiO₂) and cerium nitrate inhibitor on anti-corrosion performance of epoxy coating. First, cerium nitrate inhibitors are absorbed on the surface of various oxide nanoparticles. Thereafter, epoxy nanocomposite coatings have been fabricated on carbon steel substrate using these oxide@Ce nanoparticles as both nano-fillers and nano-inhibitors.

To evaluate the impact of oxides@Ce nanoparticles on mechanical properties of epoxy coating, the abrasion resistance and impact resistance of epoxy coatings have been examined. To study the impact of oxides@Ce nanoparticles on anti-corrosion performance of epoxy coating for steel, the electrochemical impedance spectroscopy has been carried out in 3% NaCl solution.

ZnO@Ce3+ and SiO2@Ce3+ nanoparticles provide more enhancement in the epoxy pore network than modification of the epoxy/steel interface. Whereas, Fe2O3@Ce3+ nanoparticles have more to do with modification of the epoxy/steel interface than to change the epoxy pore network.

Incorporation of both oxide nanoparticles and inorganic inhibitor into the epoxy resin is a promising approach for enhancing the anti-corrosion performance of carbon steel.

This paper aims to investigate the effect of introducing nano-ceria (CeO₂) particles to the epoxy coatings on mild steel in natural seawater.

The epoxy–ceria nanoparticles were coated with mild steel using a wire-wound draw-down bar method. The effects of ceria nanoparticles on the corrosion resistance of epoxy-coated samples were analyzed using scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS).

Localized measurements such as oxygen consumption and iron dissolution were observed using SECM in natural seawater in the epoxy-coated sample. The increase in film resistance (R_f) and charge transfer resistance (R_ct) values by the addition of nano-ceria particles in the epoxy coating was measured from EIS measurements after wet and dry cyclic corrosion test. Scanning electron microscope (SEM)/energy dispersive X-ray spectroscope (EDX) analysis showed that complex oxides of nano-ceria were enriched in corrosion products at a scratched area of the coated mild steel after corrosion testing. Focused ion beam-transmission electron microscope (FIB-TEM) analysis confirmed the presence of the nanoscale oxide layers of ceria in the rust of the steel.

The tip current at −0.70 V for the epoxy–CeO₂-coated sample decreased rapidly because of cathodic reduction of the dissolved oxygen. The increase in film resistance (R_f) and charge transfer resistance (R_ct) values by the addition of nano-ceria particles in the epoxy coating were measured from EIS measurements after wet and dry cyclic corrosion test.

The presence of complex oxide layers of nano-ceria layers protects the coated steel from rusting.

The use of this nano-ceria for corrosion protection is environment-friendly.

The results of this study indicated the significant effect of nano-ceria particles on the protective performance and corrosion resistance of the epoxy coating on mild steel. The dissolution of Fe²⁺ was lower in the epoxy–ceria nanoparticle-coated mild steel than that of the epoxy-coated mild steel resulting in a lower anodic current of steel. The increase in film resistance and the charge transfer resistance showed that the nano-ceria particles and the formation of complex oxides provide better barrier protection to the coating metal surfaces.

This study aims to report the development and experimental evaluation of three innovative corrosion-resistant modified epoxy coatings, namely, nanocomposite/toughened, self-healing and hybrid epoxy coatings, for application on steel substrates.

The corrosion resistance of these coatings was evaluated in a highly corrosive environment of salt fog spray for 2,500 h of exposure. Electrochemical impedance spectroscopy (EIS) measurements in sustained exposure to NaCl in a saturated Ca(OH)2 solution, rust creepage measurements at the location of scribe formed in the coatings and adhesion strength test were used to assess the performance of the innovative coatings. Commercially available marine-grade protective epoxy coatings were used as the reference coatings.

The test results showed that the modified epoxy coatings exhibited excellent corrosion resistance when exposed to an aggressive environment for extended periods. The EIS measurements, rust creepage measurements, pull-off strength and visual appearance of the aged modified–epoxy–coated specimens confirmed the enhanced corrosion resistance of the modified epoxy coatings.

Among the three types of modified coatings, the hybrid epoxy coating stands out to be the best performer.

In part one of this article (August 1964) the author dealt with the general chemistry, curing characteristics and applications of two‐pack and coal tar‐epoxy coatings. Part two discusses other types of epoxies and describes their uses as corrosion‐resistant coatings and pipe linings.

Epoxy resins have probably provided more interesting chemistry than any other polymer the paint industry uses. In this category of interesting chemistry is Russian work [World Surface Coatings Abstracts (1978) Abstract No. 1558] which describes the preparation of structurally coloured epoxy resins — i.e. of epoxy resins which are inherently coloured. The work involves condensing bisphenol A and epichlorohydrin in the presence of small amounts (0.1 to 0.5 weight per cent) of a coloured co‐monomer dye. The dye, for example, can be the glycidyl ether of alpha aminoanthroquinone. Coloured products resulted which presumably would provide coatings with intrinsic colour. Of course, this colour could be modified by extrinsic dyes and pigments. The concept of producing coloured polymers is not a new one. One approach to making black polyethylene for black film is to carry out the polymerisation of the ethylene in a fluid bed of carbon particles. The carbon particles presumably serve as a nucleus around which the polymer forms and at the same time serves to impart a black colour to the polymer particle. This technology has never been commercialised but it is certainly of interest to the paint chemist for it presents a new concept in carrying out a major objective of the paint industry — namely, to impart colour to solutions of polymers.

The purpose of this paper is to investigate the effect of urea–formaldehyde (UF) nanoparticles on the barrier property and delamination resistance for epoxy coating in a 3.5% NaCl aqueous solution.

The UF resin was synthesized via sol–gel method, and UF/epoxy composite coating was prepared through ball-milling process; the microstructure and chemical composition of UF resin were observed using the Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy; the bonding strength of coating/metal interface was investigated through adhesion test; the mechanical properties of the coatings were studied by tensile tests; and the barrier and corrosion resistance properties were verified using salt spray test, cathodic delamination test and electrochemical impedance spectroscopy measurements.

The experimental results indicated that the UF resin presented uniformly dispersed nanoparticles in the epoxy matrix and enhanced the bonding strength of coating/metal interface and then improved the delamination resistance for composite coating, which resulted in the enhancement of the barrier property and corrosion resistance for UF/epoxy composite coating.

In this paper, an easily prepared blending compounding coating with excellent corrosion resistance property was synthesized via sol–gel method and ball-milling process. The effects of UF nanoparticles on the barrier property and delamination resistance were investigated in detail.

This study aims to explore how the inhibitor-loaded nanocontainers can be used in the epoxy coating for protection of steel against corrosion. A self-healing anticorrosive coating can be easily fabricated by embedding the inhibitor-loaded nanocontainers into the epoxy coating matrices. For this purpose, first, cerium (a catholic corrosion inhibitor) is encapsulated into silica nanoparticles (SiO₂@Ce). Thereafter, an epoxy nanocomposite coating has been prepared on steel substrate using these SiO₂@Ce nanoparticles as nanofillers.

To examine the effect of SiO₂@Ce nanocontainers on mechanical properties of epoxy coating, the abrasion resistance, impact resistance and adhesion strength of coating have been evaluated. To reveal the effect of SiO₂@Ce nanocontainer on corrosion behavior of epoxy-coated steel, the electrochemical impedance spectroscopy (EIS) has been conducted in NaCl solution.

Transmission electron microscopy and scanning electron microscopy/Energy-dispersive X-ray spectroscopy analyses indicate that Ce³⁺ cations have been successfully loaded into the surface of silica nanoparticles (at the content of approximately 2 Wt.%). Mechanical tests of epoxy nanocomposite coatings indicate that the nanocomposite coatings with nanoparticles content of 2.5 Wt.% provide the highest values of abrasion resistance, impact resistance and adhesion strength. EIS results show that the presence of SiO₂@Ce³⁺ nanocontainers increases both coating resistance and polarization resistance. Along with the improvement the coating barrier performance, Ce inhibitor plays an important role in improving the anticorrosive performance at the steel–electrolyte interface.

The application of self-healing epoxy/SiO₂@Ce nanocomposite coatings for the protection of carbon steel is very promising.

The acute shortage coupled with tremendous increase in cost of various solvents used by paint industry and pollution becoming a serious concern has resulted in intensive study of water‐borne coatings. Water‐borne coatings ideally meet the needs for coating systems which do not cause atmospheric pollutions and at the same time help in conservation of precious and renewable petroleum resources. Many research workers have developed water‐soluble epoxies, alkyds and acrylics to make water‐based surface coatings.