Hybrid Sol-Gel Coatings: Erosion-Corrosion Protection

Introduction

Corrosion degradation is a major cause of metallic structural deterioration (Figure 1). It severely affects their service life and may result in structural failure, leakage, product loss and environmental pollution, causing large financial outlays for recovery/prevention. The World Corrosion Organization (WCO) estimates that the annual cost of corrosion worldwide is around 3% of the world’s Gross domestic product (Bhandari, Khan, Abbassi, Garaniya, & Ojeda, 2015), not considering the environmental costs due to corrosion. A passive approach to corrosion protection involves depositing a barrier layer that prevents contact of a material with the corrosive environment. Actives approaches reduce the corrosion rate when the protective barrier is damaged and corrosive agents come into contact with the metal substrate. Only the combination of both methodologies can provide reliable protection against corrosion of metallic structures.

The technological advances require more and more materials with high resistance to aggressive environments. Coatings to protect materials against erosion and corrosion are of extreme importance for both service life and maintenance cost of installations operating in aggressive environments (Szymański, Hernas, Moskal, & Myalska, 2015). The combination of degradation mechanisms, corrosion with erosion, can be several times higher than the effect of each, acting alone. Therefore, materials selection must be considered at every stage of design, construction and operation of equipment and systems. This will minimize premature failures that ultimately lead to severe economic losses and compromise the structure safety.

Figure 1.

Corrosion of a metallic support exposed to marine environment