The Influence of Nanocoatings on the Wear, Corrosion, and Erosion Properties of AISI 304 and AISI 316L Stainless Steels: A Critical Review Regarding Hydro Turbines

In the current study, the authors have listed the causes of common failures in hydro turbine blades. In the following, coatings, as one of the practical solutions that can be utilized in the hydropower industry, were selected for further investigation. In this regard, nanocoating technology is used to prevent the above-mentioned failures, as well as to extend the service lifetime of turbine blades, to increase the inspection time, i.e., the overhaul intervals, and to reduce repair costs. Therefore, firstly, the raw materials of runner blades in different types of turbines were checked. The collected data revealed that this equipment is usually made of stainless steel (i.e., 304 and 316L). Therefore, the main focus of the current research was a general investigation of the effects of different nanocoatings on the material properties, including the wear, corrosion, and erosion, of 304 and 316L steels. Finally, a coating process used in this industry that is suitable for overhaul rather than initial construction was investigated. The advantages of using nanocoatings compared to traditional coatings in this industry were enumerated. In addition, the effects of single-layer and multi-layer coatings with different compositions on the corrosion, wear, and erosion properties of each of these stainless steels were discussed. Eventually, considering the gaps in past research and summarizing the collected results, a future research direction was proposed, including different combinations of materials to create new nanocoatings (with different percentages of nano alumina and titanium carbide).