Abstract
The geothermal industry is one of the most challenging extraction and production industries that require the use of many engineered coatings solutions both in design and materials with the right cost/performance ratio. Though not widely used in geothermal wells and plants, another way of retarding the effects of corrosion is by the application of anti-corrosion coatings. Due to the relatively high-temperature demand of geothermal process, coatings must have good thermal stability, resistance to abrasion (erosion) and resistance to chemical attack. High-velocity solids impinge on the walls of the pipe, eroding the metal. Erosion together with corrosion would have a synergistic effect on the rate of metal dissolution, making it a critical factor to consider in operating under highly erosive and corrosive environment. High-temperature stable polymer nanocomposite coatings of polybenzoxazines (PBZ) modified with rubber (PBZ-R) with varying amounts of nanoclay (MMT) was investigated. The enhancement of the thermo-mechanical properties of PBZ-R by addition of MMT via polymer intercalation/exfoliation was supported by X-ray diffraction (XRD), thermogravimetric tests, hardness test, and adhesion tests. Electrochemical measurements showed good anti-corrosion properties for the nanocoatings. PBZ-R offered corrosion protection to carbon steel in acidic geothermal brine. This is due to the low water absorption capability of PBZ, preventing the corrosive fluid from penetrating the coating. The increased corrosion protection of the nanocomposite coating was optimum at 5 % MMT. The stability and protection efficiency was evaluated under higher temperature and high-pressure brine tests conditions.
