Use of plasma spray technology for deposition of high temperature oxidation/corrosion resistant coatings – a review

Abstract

High temperature oxidation is one of the main failure modes of the hot-section components in gas turbines, boilers, waste incinerations, diesel engines, coal gasification plants, chemical plants and other energy generation systems. In such applications the use of Fe-, Ni-and Co-based alloys, especially of superalloys is well known. The superior mechanical strength and good corrosion resistance of the superalloys at high temperature make them favorites for such applications. However, the presence of combustion gases constitutes an extreme environment and hot corrosion is inevitable when superalloys are used at high temperatures for long durations of time. Therefore these alloys need to be protected against this type of oxidation. Several countermeasures have been suggested in the literature to combat the same. One such countermeasure against hot corrosion and oxidation constitutes the deposition of protective coatings on these alloys. Among the various techniques used for deposition of coatings, plasma spraying is a versatile technology that has been successful as a reliable cost-effective solution for many industrial problems. It allows the spraying of a wide range of high performance materials from superalloys and refractory intermetallic compounds to ceramics with continuously increasing commercial applications. Furthermore it does not cause deterioration of the substrate alloys, and relatively thick coatings can be formed with high deposition rates. In this paper the technique of plasma spraying has been detailed and the role of plasma sprayed coatings to arrest high temperature oxidation has been discussed with the help of a comprehensive literature survey. The main focus of this investigation is the studies related to plasma sprayed NiCrAlY, Ni-Cr, Nickel aluminide and Co-based coatings.

Structure, composition, and defect control during plasma spray deposition of ytterbium silicate coatings

“…Plasma spray deposition methods have been developed over a period of nearly 70 years, and are widely used to deposit a variety of surface protective coatings [30][31][32][33]. The air plasma spray (APS) process is an economical and often reliable method for the deposition of such coatings, and has attracted attention for the deposition of EBCs on SiC components [24,25,28,29,[34][35][36][37][38].…”

Microstructure and properties of Fe-based amorphous metallic coating produced by high velocity axial plasma spraying

“…3(e) and (f). Correspondingly, the porosity measured decreased from 0.95% to 0.1%, much less than typical values of plasma spraying coating, above 1% [25]. The spraying current parameter that determines the variance in coating morphology is considered to be the reflection of melting state of the in-flight particle.…”

Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

“…Therefore, particles must have adequate velocity and temperature to deform into the irregularities from previous splats otherwise the particles bounce off the coating at impact [30]. However in it is important to ensure that particles (or most of the particles) reach their melting temperature in order to achieve the desired deposition efficiency [6].…”