Xiaodong Liu
In the highly corrosive environments typical of chemical machinery, protective coatings serve as an essential strategy to prolong equipment lifespan and enhance operational reliability. This review critically evaluates the classes, performance, and mechanical behavior of protective coatings, with a specific focus on their role in mitigating corrosion under aggressive chemical, thermal, and mechanical conditions. It discusses polymeric, metallic, ceramic, and composite coatings, examining their material compositions, deposition methods, and protective mechanisms, including barrier formation, sacrificial action, and active inhibition. The evaluation emphasizes not only chemical durability—such as resistance to acids, alkalis, solvents, and oxidants—but also high-temperature stability and the capacity to withstand operational stresses. Coating failure modes like cracking, blistering, and delamination are linked to the interplay between chemical degradation and mechanical damage. Advanced technologies, including nanostructured, self-healing, and smart coatings, are also explored for their potential to enhance performance and sustainability. Special attention is given to mechanical integrity, including hardness, adhesion, and resistance to wear and erosion, which are crucial for service longevity. Emerging trends such as environmentally friendly formulations and multifunctional hybrid coatings are positioned as promising pathways for future development. This review provides a comprehensive framework for selecting and optimizing protective coatings tailored to the multifactorial demands of chemical process industries.