Recent Advances in the Corrosion and Protection of Metallic Materials

1. Introduction and Scope

The corrosion of metals is a common phenomenon. Whether in the traditional field of metal materials, such as automotive and heat production applications, or in emerging fields, such as electronic packaging and metal batteries, corrosion behavior and the protection of metals are particularly important [1,2,3]. It is important to explore the corrosion mechanisms of metallic materials, ranging from traditional steels to special purpose metals, in various corrosion environments [3,4,5,6,7]. Moreover, electrochemical analysis will also play a crucial role in exploring the mechanism [6,7]. This Special Issue aims to report experimental and theoretical studies related to corrosion behavior, corrosion inhibitors, and the protection of metallic materials in some unusual environments, such as heat production, lithium-ion batteries, and molten zinc.

2. Contributions

Ten research articles are included in this Special Issue. The research subjects encompass the corrosion behavior of various metallic materials and corrosion inhibitors in some unusual environments. Metallic materials include steels, chromium carbide-based hardfacing alloys, nickel chromium/chromium carbides, Mg alloys, and copper foil, etc.

The processing of metals can alter the microstructure of materials, thereby affecting their corrosion behavior. Cedric Tan et al. [Contribution 1] investigated the effect of heat treatment on the microstructure and corrosion behavior of weld-deposited chromium carbide-based hardfacing alloys deposited via gas metal arc welding. The same group [Contribution 2] also contribute another work exploring the corrosion behavior of heat-treated cold spray nickel chromium/chromium carbides. Their findings highlight the critical role of controlled heat treatment in optimizing the performance of cold-sprayed Cr₃C₂-NiCr coatings. Stanislav O. Rogachev et al. [Contribution 3] investigated the influence of hot rolling on the microstructure, corrosion, and mechanical properties of Mg–Zn–Mn–Ca alloy. The strong dependence of corrosion resistance on the rolling direction is observed, which can be reduced after heat treatment.

The demand for heat production via geothermal energy is increasingly high amid the controversy surrounding non-renewable forms of energy. Geothermal waters are corrosive for geothermal installations made using carbon steels. Helali et al. [Contribution 4] investigated the corrosion inhibition of carbon steel immersed in standardized reconstituted geothermal water and individually treated with four new biosourced oxazoline molecules. Betelu et al. [Contribution 5] proposed the laboratory-scale implementation of standardized reconstituted geothermal water for electrochemical investigations of carbon steel corrosion, which demonstrated the validation of a modus operandi that properly reproduces, on the laboratory scale, operating conditions similar to those encountered in geothermal installations.

The surface modification of metallic materials is considered an effective method for improving their corrosion resistance in various environments. Electrolytic copper foil is ideal for use in the anode current collectors of lithium-ion batteries (LIBs) because of its abundant reserves, good electrical conductivity, and soft texture. However, electrolytic copper foil is prone to corrosion in electrolytes and weak bonding to the anode substance. Gan et al. [Contribution 6] fabricated a 5 nm thick phytic acid-based film on electrolytic copper foil to improve its corrosion resistance in electrolytes. Their study offered a novel avenue for the development of high-performance electrode current collector materials for LIBs. Rodič et al. [Contribution 7] prepared a superhydrophobic aluminum surface using a two-step process consisting of chemical etching in selected concentrations of CuCl₂ solution and surface grafting through immersion in an ethanol solution containing 1H, 1H, 2H, and 2H-perfluorodecyltriethoxysilane, which showed enhanced corrosion resistance, an efficient self-cleaning ability, and improved anti-icing performance.

To enhance the anticorrosion properties of molybdenum metal in liquid zinc, Liu et al. [Contribution 8] fabricated TiB₂ coatings on molybdenum substrates via the molten salt electrophoretic deposition technique and investigated their corrosion resistance in molten zinc. This experiment showed that after 120 h of immersion, the TiB₂ coating showed no signs of cracking or peeling off, successfully protecting the molybdenum metal substrate from corrosion by molten zinc.

Sonia et al. [Contribution 9] evaluated the corrosion inhibitory effects of Ruta graveolens leaf extract on 304 stainless steels in 1 M HCl, which indicated that the inhibition efficiency increased with increasing concentrations of the extract, while the reverse was true with increasing temperatures.

Testing methods play a key role in revealing the corrosion mechanisms of metals. Facundo Almeraya-Calderón et al. [Contribution 10] presented a frequency–time domain analysis based on the electrochemical noise of Dual-Phase and Ferrite–Bainite steels in chloride solutions for automotive applications, and found that the corrosion mechanism of materials begins with a localized corrosion process spreading to all the surfaces, generating a uniform corrosion process after some exposition time.