Corrosion Resistance in Aircraft: Evaluating Zirconium and Niobium Coatings for Fasteners and Leading-Edge Protection

Aircraft operate in extreme environments, making them highly susceptible to corrosion caused by moisture, temperature fluctuations, and contaminants like salt and fuel residue.This corrosion weakens structural components, increases maintenance costs, and poses safety risks, especially in critical areas like the leading edge of the wing, which plays a key role in aerodynamics, stability, and efficiency.Various types of corrosion, including uniform, pitting, galvanic, and stress corrosion cracking, affect aircraft materials differently, necessitating protective measures such as coatings, corrosion-resistant alloys, and routine maintenance.Fasteners and rivets are particularly vulnerable due to their exposure to crevice and galvanic corrosion, making proper material selection, sealing, and inspections essential for ensuring aircraft longevity and safety.A.Al-Waidh et al [1] Zirconium oxide (ZrO2) coatings were fabricated on stainless steel using a combined laser and sol-gel technique.A zirconium-based sol-gel solution was applied to the stainless steel surface, followed by laser irradiation to improve the coating's adhesion and surface morphology.Heat treatment was then applied to enhance the properties of the coating.The microstructure, phase composition, and corrosion resistance of the coatings were evaluated.The results showed that the laser/sol-gel process improved the adhesion strength and significantly enhanced the corrosion resistance of the zirconium oxide coatings on stainless steel, making them suitable for use in harsh environments.Abirami Selvaraj et al [2] The impact of zirconium oxide (ZrO) nanoparticle coatings on stainless steel and nickel-titanium wires, commonly used in orthodontics.The coating's ability to improve corrosion resistance, reduce friction, and enhance the biocompatibility of orthodontic wires.By applying zirconium oxide nanoparticles, the coating acts as a protective barrier, minimizing the wear and tear that occurs from constant mechanical movement in the oral environment and reducing the release of metal ions, which can cause adverse reactions.ZrO coatings significantly enhance the durability and corrosion resistance of these wires, thus supporting safer and more efficient orthodontic treatment with reduced risk of adverse tissue response.A.J.Cornet et al [3]As chromate-based coatings age, they become more susceptible to corrosion undercutting and pitting, particularly in high-stress areas where mechanical wear accelerates coating degradation.This deterioration can lead to localized corrosion, compromising the structural integrity of critical aircraft components, such as the fuselage and wing structures, which face constant exposure to varying temperatures, humidity, and airborne contaminants.Consequently, frequent inspection and maintenance cycles are essential to monitor coating condition and ensure early intervention, reinforcing the need for modern, eco-friendly alternatives that can provide sustained protection without the environmental and health hazards associated with chromates.Alexy Vereschaka et al [4] ZrN coatings are already known for their hardness and durability, the addition of Nb and Hf results in a denser, more refined microstructure that improves wear resistance and reduces corrosion susceptibility.This doping also enhances the coating's adhesion to metal substrates, preventing delamination and increasing component lifespan.Furthermore, the Nb and Hf doping optimizes the balance between hardness and elasticity, providing greater impact resistance and improving high-temperature oxidation resistance, making the coatings more suitable for demanding applications in industries like aerospace and marine engineering.Arash Fattah-Alhosseini et al [5] The ZrN/CrN nano-multilayer coating significantly enhances the corrosion resistance and mechanical properties of AISI 304 stainless steel by providing a robust protective layer that acts as an effective barrier against aggressive environmental conditions.The alternating layers of zirconium nitride (ZrN) and chromium nitride (CrN) create a highly durable coating that improves not only the corrosion resistance but also the hardness and adhesion strength of the stainless steel substrate.This nano-multilayer structure is particularly effective at preventing the onset of corrosion by reducing the penetration of corrosive agents, making it more resistant to pitting and general corrosion compared to uncoated stainless steel.