Effect of Exposure Conditions on the Interfacial Bond Properties of SS400 Plate Coated with Various Epoxy Resins

Abstract

This study aims to investigate the effects of different exposure conditions on the interfacial bond between steel plates and epoxy resin coatings at early ages. Test variables include the epoxy resin types, exposure conditions, exposure periods, and coating equipment. The selected epoxy resins were applied to prepared steel plates and cured at each exposure condition for 7, 28, 56, or 91 days, and the pull-off bond strength and coating thickness were measured. Scanning electron microscopy (SEM) images were obtained to study the interfacial bond for some representative coatings. Three different exposure conditions (indoors and actual marine environment) were considered in this study. This study is also focusing on the improvement of previously developed underwater coating equipment and evaluating the performance. Experiments were conducted to evaluate the performance of the improved equipment types under different environmental conditions: indoors (tap water and seawater) and outdoor conditions. The improved equipment types were confirmed to be effective for underwater coating and easier to use than the previous equipment under real sea conditions. The experimental results also confirmed that the bond strength of the coating decreased as the curing time increased.

Interfacial Bond Properties of Underwater Concrete Coated with Bisphenol A Epoxy Resins

“…Notably, D1 exhibited the highest variation with an S.D. of 123 µm, which was unexpected considering that D1 was initially anticipated to have a stable thickness compared with other methods based on previous findings [10,21,22]. The mean bond strengths of D1, D2, and D3 were 1.87, 1.70, and 1.58 MPa, respectively, and no significant difference between the groups was observed at the 0.05 significance level.…”

“…Nonetheless, it was anticipated that the bond strength measured under laboratory conditions using tap water would demonstrate a higher strength value compared to the other conditions. This expectation was rooted in our prior research, which indicated that the pull-off bond strength measured under consistent temperature and humidity conditions consistently yielded higher results when contrasted with measurements taken under real sea (RS) conditions [10,21,22]. The exact causes behind this notable onsite variability remain undetermined, but they could be linked to uncontrolled variables and unforeseen factors, including temperature fluctuations, humidity levels, tidal effects, and the presence of marine organisms.…”

“…Figure 1 summarizes the test variables used in this study. As depicted in Table 1, this study took into account three distinct types of epoxy resin and one type of hardener, guided by previous research findings [10,21,22,26]. All of the epoxy resins are readily available commercially and are suitable for use in underwater conditions.…”

Non-Destructive Evaluation of Coating Thickness Using Water Immersion Ultrasonic Testing

“…A carbon steel plate with a size of 150 mm × 50 mm × 4 mm was used as the base material to prepare the specimen. There are many coating methods, but the commonly used method in this field is to use a traditional roller to coat the surface of the substrate alone [22]. Due to manual mixing and roller coating, the coating may be thin on the four sides of the substrate or uneven in certain areas.…”

Study on Adhesion Reliability and Particle Inhibition of Epoxy Resin Coating in DC GIL after Thermal Ageing Experiment

“…At the same time, good interfacial adhesion between the coating and the electrode is necessary for the coating to play a full role. Many studies have been conducted on adhesion changes and methods to improve adhesion [24][25][26]. The coating and substrate are combined due to mechanical bite, physical adsorption with van der Waals force as the prominent role and chemical adsorption with chemical bonds as the leading role.…”