Environmentally Friendly Coatings for Improved Stainless Steel Corrosion Resistance from Biorefinery Side Streams

Abstract

Although metals are routinely used in medical implant applications, corrosion of these inserted materials is an issue that can potentially have significant health impacts. For example, Stainless steel (SS) 316L - one of the most commonly used implant substrates - undergoes corrosion under physiological conditions. Such material degradation leads to the release of various potentially carcinogenic ions (e.g. Fe, Cr, Ni1,2) and over 90% of SS 316L implant failures are estimated to as a result of corrosion2. Fortunately, many of these difficulties can be mitigated through the use of biocompatible coatings on implant surfaces. In this research, the effect of a lignin-based coating on SS 316L corrosion resistance was investigated. Two distinct types of lignin (from Soft and Hardwood) were dissolved in solvent and spin-coated on SS 316L. Subsequent surface characteristics were analysed by different techniques (AFM, FTIR) and the corrosion resistance of the obtained surfaces were studied by electrochemical methods. Results show that the presence of a lignin coating leads to an increase in surface wettability, whilst decreasing the measured corrosion current density of the metal by 2-3 orders of magnitude. Overall, this research clearly highlights the potential of lignin from Biorefinery side streams as a sustainable and environmentally friendly coating for corrosion protection. Keywords: Lignin, organic coatings, spin coating, SS316L corrosion The authors acknowledge the Technology Industries of Finland Centennial/Jane and Aatos Erkko Foundations “Future Makers: Biorefinery Side Stream Materials for Advanced Biopolymer Materials (BioPolyMet)” project for funding this research. In addition, this work made use of facilities provided by the RawMatTERS Finland Infrastructure (RAMI) at Aalto University, which is supported by Academy of Finland. References Shih C, et al. Growth inhibition of cultured smooth muscle cells by corrosion products of 316L stainless steel wire. J Biomed Mater Res. 2001;57(2):200-207Douglas CH. Metal corrosion in human body: The ultimate bio-corrosion scenario. The Electrochemical Society INTERFACE. Summer 2008;17(2):31