Investigation of Accelerated Degradation Methods to Cause Blisters for Non-Defective Vinyl Ester Resin Glass Flake Organic Coatings

Organic coatings are applied as a corrosion prevention measure, but their effectiveness may degrade over time. In this study, the acceleration effects of typical degradation methods in non-defective vinyl ester resin organic coatings containing glass flakes such as high-temperature immersion and immersion in chemical accelerators are clarified using physiochemical techniques. Immersion in an acetic acid (AcOH) aqueous solution causes resin swelling, and the behaviors are quantitatively evaluated through gravimetric, thickness, and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, a combined process of immersion in hydrofluoric acid and an AcOH aqueous solution reduces the electrical properties and eventually blisters the thick coating surface. This result suggests that an appropriate combination of the resin swelling and the glass degradation (glass dissolution and/or formation of the gap between glass and resin) decrease mechanical properties of the glass flake coating and causes blisters. In order to help the health diagnosis of the visually non-defective aged glass flake coating, the relationship between the electrical characteristic values and the invisible degradation by accelerated tests is finally indicated.

Detection of different chemical binders in coatings using hyperspectral imaging

Organic coatings protect metallic structures of significant commercial value. Regular inspections of coatings are required to ensure their integrity and, therefore, to verify their stated performance. However, for metallic structures located in harsh places, coating inspection can pose significant safety and logistical challenges. Near-infrared (NIR) spectroscopy is a rapid, nondestructive and relatively inexpensive analytical technique. It is currently employed to analyze different chemicals in fields like agriculture, food, and pharmaceuticals. Similarly, hyperspectral imaging (HSI) creates a spatial map of spectral information by measuring light reflected from a material. In this work, hyperspectral imaging in the NIR portion of the electromagnetic spectrum (NIR-HSI) is used to accurately distinguish between the chemically different binders employed in commercial organic coatings. In addition, k-means clustering is explored as a tool to provide diagnostic information about the spatial inhomogeneities in the chemical structure of an applied coating, which, if undetected, can lead to coating defects during service life. The results of this work suggest that the NIR-HSI could be used for remote inspections of organic coatings.

Anti-Caking Coatings for Improving the Useful Properties of Ammonium Nitrate Fertilizers with Composition Modeling Using Box–Behnken Design

Granular fertilizers (especially those based on ammonium nitrate (AN)) tend to agglomerate during storage. The aims of this research were to develop effective anti-caking coatings for ammonium nitrate fertilizers while improving the quality of fertilizers and to optimize the composition of effective anti-caking coatings. The influence of the composition of the prepared organic coatings on the effectiveness of preventing the caking of fertilizers was studied by response surface methodology (RSM) using Box–Behnken design (BBD). Additionally, the effect of the developed anti-caking agents on the quality of fertilizers was determined by measuring the crushing strength of the granules. The prepared coatings included fatty amine, stearic acid, surfactant, and paraffin wax. Gas chromatography–mass spectrometry (GC–MS) was used to analyze these coatings. The morphology of the fertilizers were examined by scanning electron microscopy (SEM). Composition studies, based on statistical assessment, showed the coating components had a varying influence on preventing the caking of fertilizers after granulation and after 30 days of storage. The results demonstrated that increasing the content of fatty amines and reducing surfactant in the composition of coating had positive effects on caking prevention. In this study, more effective and economically viable anti-caking coatings were developed. In addition, the present work could serve as a basis to further improve anti-caking coatings.