RESUMEN
Asphaltene deposition in petroleum refineries is known to be problematic as it reduces efficiency and may lead to structural failure or production downtime. Though several successful approaches have been utilized to limit deposition through the addition of dispersants and inhibitors to petroleum, these methods require constant intervention and are often expensive. In this study, we demonstrate an innovative technique to engineer the surface chemistry of pipeline steels to inhibit asphaltene deposition. Pack aluminization, a standard industrial-scale chemical vapor deposition process, is employed at a low temperature of 600 °C to aluminize API 5L X65 high strength pipe steel substrates. The results showed deposit-free steel surfaces after high-pressure and high-temperature fouling experiments. The improvement is attributed to the formation of an aluminide intermetallic phase of Fe2Al5, which changes the native oxide chemistry to favor alumina over hematite. The continuous passivating oxide scale, acting as a protective barrier, mitigates asphaltene deposition and sulfidic corrosion. Because this process is based on alloying the surface of the steel and is not a coating with a weakly adhered interface, it is not prone to delamination, and it can be re-formed when damaged within the aluminized region. The combination of low-cost processing and improved antifouling characteristics makes surface chemistry modification of steel a promising preventative approach against asphaltene deposition.
RESUMEN
Silicon-based microelectromechanical systems (MEMS) sensors have become ubiquitous in consumer-based products, but realization of an interconnected network of MEMS devices that allows components to be remotely monitored and controlled, a concept often described as the "Internet of Things," will require a suite of MEMS materials and properties that are not currently available. We report on the synthesis of metallic nickel-molybdenum-tungsten films with direct current sputter deposition, which results in fully dense crystallographically textured films that are filled with nanotwins. These films exhibit linear elastic mechanical behavior and tensile strengths exceeding 3 GPa, which is unprecedented for materials that are compatible with wafer-level device fabrication processes. The ultrahigh strength is attributed to a combination of solid solution strengthening and the presence of dense nanotwins. These films also have excellent thermal and mechanical stability, high density, and electrical properties that are attractive for next-generation metal MEMS applications.