Effect of Zinc Phosphate on the Corrosion Behavior of Waterborne Acrylic Coating/Metal Interface

Enhancing Self-Healing and Adhesion Bonding Properties: Investigating the Promising Potential of Ce-ZIF8 MOF Hybrid Thin Films as pH-Responsive Nanocoatings

Further modification of the pre-treated steel surface with cerium conversion coating was performed using a novel porous coordination polymer (PCP) based on zeolitic imidazole framework-8 (ZIF8) in order to reduce the defect and disorders of the surface. The treated mild steels (MS) with Ce (MS/Ce) and Ce-ZIF8 (MS/Ce-ZIF8) were characterized by the GIXRD, Raman, and FT-IR, and via contact angle and FE-SEM, their surface features were investigated. The protection performance of the samples against corrosion was evaluated in the saline solution media using electrochemical impedance spectroscopy (EIS, in the long term) and polarization tests. The results evidenced that applying the ZIF8 nanoparticles onto the Ce-treated steel surface increased the total resistance value after 24 h of immersion (49.47%). Afterward, the ZIF8-modified coating (MS/Ce and MS/Ce-ZIF8) impact on the epoxy coating protection function was characterized by EIS (in the scratched form), salt spray (5 wt % salts), cathodic disbonding (at 25 °C), and pull-off tests. The EIS outcomes of the scratched coatings proved approximately a 51.29% increase in R_t of the MS/Ce-ZIF8/EC sample compared with the MS/EC sample after 24 h of immersion. The cathodic disbonding test results after 24 h of exposure revealed that the delamination area of the coating decreased in the modified sample, and the delamination radius of the epoxy coating was about 4.78, 2.96, and 2.0 mm for the MS/EC, MS/Ce/EC, and MS/Ce-ZIF8/EC samples, respectively.

Corrosion Protection and Heat Resistance of Paints for Outdoor Use

Innovative heat- and corrosion-resistant coating approaches, applicable in indirect-food-contact outdoor environments, have been developed. Two systems, a direct-to-metal single-layer, polysiloxane-based, oven-dried system and a bilayer, zinc phosphate active pigment-containing, ambient-cured system were developed to overcome the shortcomings of the traditional bilayer, zinc-rich primer-based heat-resistant surface-protective solutions for outdoor cooking equipment, such as barbecue grills. This case study aims to optimize the application conditions, measure and evaluate the impact of surface preparation and compare thermo-resistant and anticorrosive properties of different coating systems focusing on eco-efficiency. The anticorrosion efficiency of the coatings was characterized using salt-spray chamber corrosion tests and electrochemical impedance spectroscopy. The thermo-resistant character of the coatings was tested by cyclic and constant heat treatment, after which the physical integrity of the coatings was evaluated by optical microscopy. In the overall performance of the coatings, the roughening of the steel substrate surface and the thickness of the coatings were also considered as influential parameters. The study revealed that the newly developed coatings have superior anticorrosion performance to the usually applied Zn-rich coating. The Single-layered Coating has excellent corrosion resistance under certain conditions and has the advantage of fast layer application. The Bilayered Coating showed excellent heat- and corrosion-resistance properties even on a surface without sand-blasting.

Durability and Corrosion Properties of Waterborne Coating Systems on Mild Steel Dried under Atmospheric Conditions and by Infrared Radiation

Increasing attention is given to waterborne coatings for corrosion protection due to the lower ecological impact on the environment. It has been found that by using waterborne coatings, the emission of harmful volatile organic compounds (VOCs) is reduced by more than 50 g/L. However, they require longer drying time, their anti-corrosion performance is not as good as solvent-borne coatings and they still have not been developed for all corrosion environments. Another way to reduce VOCs is by using infrared (IR) drying technology. With catalytic infrared radiation, it is possible to cure all surfaces at notably reduced costs compared to traditional systems and in total respect for the environment, thanks to significant energy savings and minimal CO₂ emissions. The aim of this paper was to evaluate corrosion protective properties of waterborne coatings which were dried with traditional and accelerated drying techniques, i.e., under atmospheric conditions and by using IR technology. Two different coating systems were applied, with and without Zn in the primer. To achieve this goal, the test samples were subjected to electrochemical, corrosion, and physical tests. It was shown that infrared technology does not affect the quality of the coating and it drastically reduces the intercoating interval. A coating system with zinc in the primer showed better overall protection properties after being subjected to impedance and salt spray testing, but generally, solvent-borne coatings still have higher durability than waterborne in extreme marine conditions according to recent research. Microstructure and porosity remained intact and the atomic force microscope confirmed that the flash-off was conducted correctly since there were no pinholes and blisters detected on the coating's surface. This study can serve as a foundation for further investigations of IC-dried waterborne coatings because there are not many at the moment.

Influence of Anticorrosive Pigment, Dry-Film Thickness and Conditioning Time on Protective Properties of Two-Component Epoxy Primer

The main protective properties of two-component epoxy coating are connected by the formation of a barrier of a certain thickness between the material and aggressive, environmentally induced reactants. Anticorrosive pigment is added to the coating in order to improve its protective effects. The conditioning time refers to the time interval required for the achievement of satisfactory cohesion bonds between the coating components, as well as a satisfactory adhesion force between the coating and the base material surface. This paper presents insights obtained after experimental research into the influence of input variables (the content of anticorrosive pigment in the coating, dry-film thickness, and conditioning time) on corrosion resistance. The specimens were kept in the aggressive atmosphere of a salt-spray test chamber within time intervals of 120, 240 and 480 h, where they were cyclically sprayed with a 5% sodium chloride (NaCl) solution, and then examined in laboratory conditions. Such a procedure imitated the aggressive conditions of a service environment. After exposure in the salt-spray test chamber, the specimens were tested to determine the protective properties of the coating and to evaluate damage occurring on the coating, with the purpose of assessing the coating quality in relation to the stated input variables. At all times, when the test samples were exposed to the salt chamber atmosphere, the anti-corrosion pigment content was found to have the greatest influence with the thickness of the dry coating film. The conditioning time was an influential factor to a lesser extent, and only in some observed cases. By analyzing the interactions of the input variables and the results obtained based on mathematical models and reaction surfaces, it was possible to define the most optimal values of the input parameters. For example, after 480 h of exposure in a salt chamber, notch corrosion of 0.6 mm was observed at a dry-film thickness of D1 and an anti-corrosion pigment content of 10%.

Optimization of Parameters for Protection of Materials by Primer Application

The protective properties of coating systems usually depend on their base layer, since its characteristics and chemical composition are greatly responsible for prevention of corrosion development. Moreover, a good primer as a base coating has to provide good adhesion between the coating system and the substrate material, as well as good cohesion, i.e., coating strength. The described experiment aimed to determine the influence of input parameters (anticorrosive pigment content, conditioning time, dry film thickness) on the adhesion properties of the coating. The optimization of input parameters was achieved by the pull-off test in order to determine their maximum values. For the purpose of imitating aggressive atmosphere of service conditions, the experiment was run in a salt spray chamber, in which samples were cyclically sprayed with 5% sodium chloride (NaCl) solution for 120 h. The obtained mathematical model makes it possible to define the optimal values of the input variables for the defined values of the required property, i.e., the adhesion properties of the applied primer for certain exploitative conditions.

Effectiveness of Epoxy Coating Modified with Yttrium Oxide Loaded with Imidazole on the Corrosion Protection of Steel

The search for highly effective corrosion protection solutions to avoid degradation of the metallic parts is enabling the development of polymeric organic coatings. Of particular relevance, polymeric nanocomposite coatings, modified with corrosion inhibitors, have been developed to provide enhanced surface protection. In this work, yttrium oxide nanoparticles loaded with corrosion inhibitor (Imidazole), used as additives in the formulation of epoxy for coated on the steel substrate. The loading of Y₂O₃ with imidazole was confirmed by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller analysis. UV-Vis analysis demonstrated the pH-sensitive behavior of the imidazole that helps in self-release when necessary. Electrochemical impedance spectroscopy (EIS) of the coated samples revealed that the coating modified with Y₂O₃/IMD provides better corrosion protection compared to coatings containing only Y₂O₃. XPS analysis validated the presence of an imidazole protective film on the steel substrate that enhanced the corrosion resistance of the coated samples

The Development of a Surface Finisher of Car Park Slab Using Waterborne Silicon Acrylic with Polyamide [Part II: Safety Tests]

Due to the environmental concerns of solventborne coating systems, environmental directives have recently been promulgated in many countries. Additionally, integrated environmental policies have been pushed in many fields to minimise influences on the environment. Waterborne silicon acrylic finishers have gained much interest to replace the traditional finishing system. To satisfy the requirements, a waterborne finisher with polyamide was previously developed and its performance was determined. For further safety assessment, various tests were conducted, such as gas toxicity, heavy metals tests, chemical resistance test and chloride migration test, followed by equivalent standards. In the cases of gas toxicity and heavy metals evaluations, both results were acceptable considering their corresponding standards, e.g. KS F 2271, KS F 3888-2 and BS EN 71-3. Based on the evaluation, silicon acrylic with 30% mix ratio of polyamide resin (SA+PR30%) could be implemented as an environmentally friendly finisher for various applications. In the chemical resistance and chloride migration test results, the developed finisher showed a barrier effect in the chemical environment. Thus, the developed finisher could be an alternative finisher applicable for slabs in chemical industrial areas.

Cold Bonding Method for Metallic Powder Coatings

An efficient and simple method for preparing bonded metallic powder coating is in high demand in the paint manufacturing and application industries. The bonding purpose is to keep the mass percentage of metallic pigment consistent between the original and recycled coating powder, which aims at solving the problem of recyclability. One possible method capable of realizing this goal is using the binder to cohere metallic pigment with base particles through a cold bonding method. Through this approach, the pre-curing and high-reject-rate problems generally present in thermal bonding can be completely eliminated. In this paper, polyacrylic acid (PAA) and polyvinyl alcohol (PVA) are applied as binders for the bonding process. At various dosages of liquid binder and D.I. water, bonded samples with different bonding effect were prepared. Finally, a good bonding quality with the lowest variance between the mass concentrations of Al flakes in the original powder (before spray) and deposited powder (after spray) 2.94% with PAA as a binder and 0.46% with PVA as a binder was achieved. These results manifest that the cold bonding method is a green and simple approach for preparing the metallic powder coating.