Improvement in Slurry Erosion and Corrosion Resistance of Plasma-Sprayed Fly Ash Coatings for Marine Applications

Abstract

Fly ash (FA), a multicompound mineral, is an industrial waste produced during coal burning in thermal power stations. It has been regarded as the most environmentally hazardous material. Furthermore, handling FA has been a significant challenge for many developing countries. Therefore, researchers have been exhorted to enhance its usage to counter its handling issues. FA is enriched with mullite, silica, and alumina. Having such mineralogy, FA can be envisaged as a promising candidate for combating erosion and corrosion in marine environments. With this motivation, the research aims to deposit as-received FA using the plasma-spraying technique onto a marine-grade steel substrate without additives and assess the performance of such coatings for erosion and corrosion properties. The coating has exhibited more than 100% improvement in microhardness. The erosion resistance was improved by ∼11% compared to that of the uncoated sample, which is attributed to the hardness to elastic modulus ratio ( H / E ) and its unique mineralogy. The minor improvement in erosion resistance was attributed to the coating’s poor fracture toughness. The erosion study shows that slurry concentration and rotational speeds were the most influential parameters. The scar depth was significantly shallower for FA-coated samples. The corrosion resistance has improved only by ∼13.49%, owing to the porous nature of the coating. Therefore, such coatings with appropriate improvements in their properties are expected to assuage both environmental and industrial challenges.

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors

“…Prior to deposition, the work surface (30 mm × 25 mm) of the substrate was sandblasted and roughened and then immersed in acetone solution for ultrasonic cleaning for 20 min. To ensure a high bond strength and long service life, , the thickness of both coatings was controlled at about 300–310 μm, and their optimum spraying parameters are provided in Table S4. Subsequently, the coatings were polished to mirror surface ( R a ≤ 0.1 μm) with SiC sandpapers (800–2000 meshes) and water-borne diamond paste with a 0.5 μm particle size.…”

An Investigation into the Relative Efficacy of High-Velocity Air-Fuel-Sprayed Hydroxyapatite Implants Based on the Crystallinity Index, Residual Stress, Wear, and In-Flight Powder Particle Behavior

“…Before deposition of the HA coatings, the 50 × 25 × 4 mm Ti-6Al-4V substrates were grit blasted using a hot grit blaster (GB-02 HVAF blast feeder supplied by Kermetico, Inc.), and HA was deposited by following the parameters of Table . The substrate was preheated to ∼200 °C to remove moisture and roughened , before depositing, and the substrates were cleaned with acetone before and after grit blasting. Surfaces were grit blasted using alumina grits for around 2–3 min.…”

Dynamic response of 3D printed functionally graded sandwich foams

“…Mostly cenosphere and glass microballoon (GMB) are used as the reinforcement in developing syntactic foams (Patil et al , 2019; Bharath et al , 2021b). These fillers are not only used in developing syntactic foams but also in wide variety of industries, for example, cenospheres are used in applications like thermal barrier coatings (Chavana and Bhajantri, 2022). Previous studies on GMB-based foams have shown that these syntactic foams have a good weight reduction potential, strength-to-weight ratio and low moisture absorption (Doddamani et al , 2015; Bharath et al , 2020a; Nikhil, 2007).…”