Ceramic coatings are commonly used as barrier coatings to protect the metal surface against corrosion due to possessing better wear, corrosion and heat resistant properties than metals. Titanium dioxide is one of the extensively used ceramic coatings for a broad range of applications including solar cells, self-cleaning, air purification and biomedical applications. Since coating microstructures and properties vary with the deposition method, thermal spray coatings are very promising in terms of corrosion and wear resistance. High-velocity oxy-fuel (HVOF) spray method is a commercially used eco-friendly coating method that provides better control over coating properties than most thermal spray techniques. Here, TiO2 coatings are deposited on carbon steel substrate using suspension-HVOF spray. Commercial aqueous suspension of TiO2 nanoparticles was used as a feedstock material, and sprayed at two different flowrates. The morphological analysis of the developed coatings was conducted using scanning electron microscope. To understand the wetting behavior, roughness profile, adhesion and scratch resistance of coatings, drop size analyzer, profilometer, adhesion and scratch tests were performed. Further, samples were immersed into 3.5 wt.% NaCl solution to compare the corrosion behavior of both coatings.
With the increased pollution and energy demand, industries are shifting towards cleaner and greener power generation source. Geothermal energy, where energy is derived from the sub-surface of earth, is an excellent and continuous source of energy. Despite having the potential of providing cleaner energy, there is a huge gap between the theoretical potential of geothermal power plants and their practical applications. Some of the major reasons are high power generation cost and poor efficiency of the plant. The components of geothermal power plants, especially heat exchangers suffer from poor durability due to constantly being in an aggressive environment (varied temperature and pH, brine, steam, acids, etc.) of the plant that give rise to corrosion and scaling. Hence, the operational and maintenance cost of the plant increases. Typically, expensive metals or alloys are used to avoid corrosion and scaling, which further contributes into the increased cost of power generation. Therefore, coatings with unique surface geometries are preferred as they protect the metal/alloy surface but also increase their heat transfer. Generally, various active and passive techniques are used to improve the heat transfer between surface and liquid. However, due to the lower energy requirement, passive techniques such as development of unique surface geometries are widely preferred [1]. The optimized surface geometries might improve the heat transfer efficiency as well as reduce the cost of heat exchangers that could be used in a broad range of industries. Surfaces with engineered micro- or nano-scale features are extensively preferred due to their enhanced surface area.
