Seawater Corrosion of Copper and Its Alloy Coated with Hydrothermal Carbon

Abstract

Nonferrous materials such as copper and its alloys are sensitive to seawater corrosion. In this work, a hydrothermal carbonization coating was deposited on a C26000 brass and pure copper. The effectiveness of the coating on improving seawater corrosion performance was examined. First, hydrothermal carbonization of sugar (with 10 wt.% sucrose in water) at 200 °C and 1.35 MPa for 4 h was performed to generate the carbon-rich coating. The results of surface morphology, composition, hardness, thickness, and wettability to seawater were presented. Then, the corrosion resistance of the brass and pure copper with and without coating was evaluated by measuring the Tafel constants in seawater. Important parameters including the corrosion current, potentials of corrosion, and polarization resistance for the brass and pure copper with and without the coating were calculated from the polarization measurement data. It was found that the hydrothermal carbonization of sugar produced a relatively dense carbon-rich layer on the surface of the copper and brass specimens. This carbon layer has a thickness of 120 µm, and it is highly corrosion resistant. The corrosion current of the copper and its alloy in seawater is reduced significantly through the hydrothermal carbonization treatment. The carbonized coating reduced the corrosion current obviously, but only resulted in a small positive shift of 0.05–0.1 V in the corrosion potentials. The hydrothermally produced carbon layer is just like a passivation coating on the pure copper and copper alloy to slow down their corrosion rates in seawater.

A Brief Summary of Publications in the Special Issue: Advances in Corrosion Resistant Coatings

“…To improve the corrosion resistance of copper-zinc alloys to seawater in the marine environment, hydrothermal synthesis of a carbonized coating was conducted in [5]. Although hydrothermal synthesis [6] has been reported for nanomaterial production, its new application for making surface coatings to protect materials from corrosion is introduced in this paper [5]. The hydrothermal carbonization coating was formed on both brass (a Cu-Zn alloy with the designation of C26000) and pure copper.…”

Special Issue: Advances in Corrosion Resistant Coatings Volume II

“…It is confirmed that Pt as a dopant has a critical role in improving the conductive behavior and enhancing the corrosion resistance of nitride coatings for potential applications in off-shore structures. To increase the seawater corrosion resistance of a copper-zinc alloy in the marine environment, a hydrothermally carbonized coating was prepared [8]. The hydrothermal processing method [9] has been studied for nanomaterial production.…”

“…The hydrothermal processing method [9] has been studied for nanomaterial production. However, its new application for making surface coatings to slow down material degradation is only introduced in this study [8]. The hydrothermally carbonized coatings were deposited on both pure copper and its alloy, C26000 brass.…”