Recent Trends in Applications of X-ray Photoelectron Spectroscopy (XPS) Technique in Coatings for Corrosion Protection

Abstract

Corrosion-primarily a surface phenomenon, strongly influences an asset's performance, durability, and reliability, as costs of corrosion-related repairs and refurbishment can run into millions of dollars. Notably, in the Middle East region, direct corrosion costs are estimated to be approximately 5% of the gross domestic product (GDP), a value that represents an enormous economic burden. In this context, the corrosion of metals is one of the most fundamental causes of components and equipment failure across different industrial sectors. In the oil and gas sector, extreme operating conditions and corrosive environments exacerbate the extent and seriousness of corrosion and result in a vast majority of component failures. Therefore, a comprehensive understanding of corrosion mechanisms and processes taking place on a component's surface is vital for efficient and cost-effective asset integrity management. Various advanced analytical techniques such as X-ray Photoelectron Spectroscopy (XPS), X-ray fluorescence (XRF) spectroscopy, Localized Electrochemical Impedance Spectroscopy (LEIS), Scanning vibrating electrode technique (SVET) and Scanning Ion-Selective Electrode Technique (SIET) provide useful quantitative information about corrosion. Amongst those, XPS is one of the most sophisticated technique that can be smartly utilized to study corroded surfaces, protective coatings and understanding of various corrosion mechanisms. XPS can also be effectively used to assess corrosion byproducts to understand the various surface reactions, localized surface chemistry and alteration in electrical responses under different corrosive environments. This chapter focuses on the utilization of XPS technique in coatings for materials protection. Special attention is paid to cover its role in compositional analysis of various types of coatings (metallic and polymeric) that are actively investigated for corrosion protection. At the same time, use of XPS can also be extended to explore smart polymeric coatings confirming the self-release of various inhibitors and self-healing agents loaded in nanocarriers. Furthermore, the role of XPS in post corrosion analysis is described, which provides ample information to understand the corrosion protection mechanism. A short note on future scope and challenges faced by XPS technology in corrosion research is also provided for the interest and motivation of the readers to excel in this important area of research.