1st Cut Spent Pot Liner-Modified Epoxy Coatings for C-Steel

Abstract

Aluminum extraction from alumina is conducted in huge electrolytic cells, arranged in ‘pot lines’. These pots have a carbonaceous lining to act as the cathode. After a few years of service, this lining is ‘spent’ and must be replaced. This waste material, called 1stcut Spent Pot Lining (SPL1), is collected in thousands of tons. SPL1 is considered a ‘hazardous’ material by the US Environmental Protection Agency and its European counterpart. Storage, transportation and treatment of SPL1 is a major problem for the aluminum industry. In the most common recycling procedure, SPL1 is treated either thermally or chemically by expensive processes to retrieve the carbon, which is then used as fuel. Alternative uses for this carbon-rich material in other applications are being explored. Epoxy resin is a thermoset polymer coating material which has wide industry acceptance due to its toughness, adhesion, durability, thermal stability, high chemical resistance, low shrinkage and ease of fabrication. However, epoxy coatings suffer from brittleness, a poor resistance to crack propagation especially in presence of UV radiations. It is expected that addition of carbon-based conductive fillers can decrease the susceptibility of epoxy to aggressive UV radiation and thus increase its corrosion protection properties. The objective of this work is to explore the use of SPL1 as an additive in fast-cure epoxy coatings on mild steel substrates and study the thermal and electrical properties of the resulting composite at various concentrations of functionalized and unfunctionalized SPL1. The weathering behavior of these coatings under UV radiation were also investigated. The results showed that the electrochemical corrosion behavior of the coating was significantly improved although some microcracks developed on the surface of the coatings after prolonged exposure to UV radiation. Figure 1