Static Electroplating of Iron Triad on Fastener Washers

Fasteners are commonly used in construction industry for parts joining purpose. There are many types of construction fasteners such as stud, bolt, anchor, nut, screw, and washer. The major problem of the fastener made by carbon steel is the poor resistance to corrosion. Electroplating is a simple yet low-cost tool to give a strong corrosion protection coating layer on the carbon steel. This study was performed to investigate the effect of current and deposition time on the iron triad (cobalt-nickel-iron) electroplating on the fastener washer. The experiment was conducted at 50 °C, pH 1-3 and at different electroplating time (30 minutes to 90 minutes) and current (0.2 A to 0.5 A). Burnt-out surface coating was observed on the fastener washer when the current was more than 0.4 A. A field test was carried out for 60 days to observe the corrosion behavior and performance of the products. Scanning electron microscope (SEM) analysis showed that a thin protection layer with 5.64 µm was formed at 60 minutes of electroplating time and 0.4 A of current. The surface roughness of the fastener washer was increased by increasing the electroplating time and current. The hardness was also improved with higher current and electroplating time if compared to the original fastener washer. The result of this study confirmed that a strong adhesive corrosion resistant layer to the fastener washer was using the current of 0.4 A (77 mA/cm2) and the electroplating time of 60 minutes.

Preparation of graphene oxide–boron nitride hybrid to reinforce the corrosion protection coating

Coatings based on a graphene oxide–boron nitride/epoxy (GO–BN/EP) system were fabricated and applied for corrosion protection of metal substrates. GO–BN hybrid sheet synthesized by using a modified Hummers’ method had a higher lipophilicity than GO and BN. Then, GO–BN hybrid was incorporated into an epoxy coating to investigate the compactness and the corrosion protection ability of GO–BN hybrid/epoxy coating for metal substrates. The results show that GO–BN hybrid presents a desirable dispersibility in epoxy coating, exhibiting an outstanding barrier property for corrosive ions in a 3.5 wt% NaCl solution among the four systems under investigation. The present study set forth an innovative method to synthesize GO–BN hybrid in the field of corrosion protection.

Investigation of Using Sol-Gel Technology for Corrosion Protection Coating Systems Incorporating Colours and Inhibitors

Corrosion protection coatings need frequent developments to cater to different challenges arising from users. In addition to a long lasting corrosion protection, aesthetic requirements and multi-functional properties by the same coating system are prominent demands to be considered. Productivity is another vital factor to be considered, as there is a thriving demand from users to have more productive coating systems, such as a smaller number of layers in a system. Thus, attention to using different coating technologies is an essential step to fulfil these demands. This work investigates the use of sol-gel technology as a topcoat on a zinc rich primer to form a two-coat system. A colored sol-gel topcoat on a zinc primer was developed as a two-coat system to replace the current three or multi-coat systems to improve productivity while maintaining the sacrificial protective capability. The overall corrosion protection performance together with the color retaining capability was evaluated in this development. As another step forward, the development of sol-gel technology as a topcoat with additional inhibitive corrosion protection was investigated. Two corrosion inhibitors, namely molybdate and cerium(III), were loaded onto suitable inorganic oxide carriers and then incorporated into sol-gel coatings to provide an inhibitive protection other than the barrier protection. The corrosion performance of the coatings was evaluated using electrochemical impedance spectroscopy (EIS). Sol-gel coating with a cerium(III) system attained the highest impedance and proved to be the best candidate. The mechanical and physical properties of the coating systems are tested using international standard methods.