Materials World Network, SusChEM: Hybrid Sol-Gel Route to Chromate-free Anticorrosive Coatings

TECHNICAL SUMMARY: Surface treatments with Cr(VI) are a common industrial practice for passivating metals. However, Cr(VI) is a known carcinogen. Replacement of Cr (VI)-containing coatings with new chromate-free anticorrosive coatings is a public health priority. This research investigates the formation of doped and undoped hybrid organic-inorganic glasses, which are obtained by consolidating "melting gels". Melting gels are hydrophobic, nonporous and gas impermeable with low sealing temperatures (between 135 and 200 degrees centigrade), and they can be applied directly onto metals and other substrates. The research focuses on the structural and chemical aspects of melting gels that limit gas permeability and impart protection to metal surfaces. One substrate of interest is magnesium, because of its low density, high strength, good thermal and electrical conductivity, and low elastic modulus, making magnesium alloys with improved corrosion protection particularly interesting in auto, aerospace and biomedical applications. With support from the Division of Materials Research, this Materials World Network, Sustainable Chemistry, Engineering project is built on a strong collaboration between the PIs Andrei Jitianu (Lehman College City University of New York) and Lisa Klein (Rutgers University) from US and Mario Aparicio (Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (CSIC)) from Spain. NON-TECHNICAL SUMMARY: Traditional anti-corrosion coatings for metals contain Cr(IV), a toxic material known to cause cancer. In an effort to replace this harmful material with a safer alternative, the project will prepare and study a use class of hybrid organic-inorganic "melting gels" that contain corrosion inhibitors. Melting gels are non-porous barriers obtained by a simple process that requires low temperature processing. They prevent environmental degradation of metals through their adherence to metals and their ability to hinder the transport of gases and water vapor through the coatings. Our Materials World Network consists of 3 partners, the Chemistry Department at Lehman College, the Materials Science & Engineering Department at Rutgers University, and the Institute for Ceramics and Glass (CSIC) in Madrid, Spain. By combining the expertise of three laboratories with experience in sol-gel processing and electrochemical testing, the team will complete a comprehensive study on the mechanisms for forming corrosion protection coatings for magnesium alloys and steels, which are used commonly for aerospace, automotive, and biocompatible medical implant applications. Through this research program, greater understanding and practical know-how in the use of melting gels for anticorrosive and hermetic barrier applications will be shared. At the same time, this program will educate students in relevant topics of chemistry, materials science and corrosion through an international multidisciplinary approach. Exchanges of scientists and students are planned to make a more comprehensive study of anticorrosive coatings. Opportunities for students from underrepresented groups will be included by the participation of Lehman College-CUNY, a federally recognized Hispanic minority serving institution.