Characterization and High-Temperature Oxidation Behavior of Cold-Sprayed Ni-20Cr and Ni-50Cr Coatings on Boiler Steels

Abstract

Microstructure and mechanical properties of cold-spray coatings are usually required in order to explore the potential industrial application of the latter. This article demonstrates the successful formulation of Ni-20Cr and Ni-50Cr coatings on two boiler steels, namely, SAE 213-T22 and SA 516 steel by cold-spray process. The microstructure, coating thickness, phase formation, and microhardness properties of the coatings were evaluated. The coatings were subjected to cyclic heating and cooling cycles at an elevated temperature of 1173.15 K (900°C) to ascertain their high-temperature oxidation behavior. Moreover, these cyclic exposures can give useful information regarding the adhesion of the coatings with the substrate steels. Of all the coatings, the Ni-50Cr coating on SA 516 steel had a maximum average hardness value of 469 Hv. As observed from the surface field emission-scanning electron microscopy (FE-SEM) analysis, the coatings were found to have nearly dense microstructure with the sprayed particles in interlocked positions. It was concluded that the cold-spray process is suitable for spraying the preceding powders onto the given boiler steels to produce nearly dense and low oxide coatings. The coatings, in general, were found to follow the parabolic rate of oxidation and were successful in maintaining their surface contact with their respective substrate steels.

A Review of Advanced Composite and Nanostructured Coatings by Solid-State Cold Spraying Process

“…90,189 (3) A Ni-Cr composite can be used as oxidation resistant coating. 99 (4) A Cu-In composite can be used as a sputtering target. 190 (5) A Cu-Cr coating can be used as an electrical contact material for its excellent electrical conductivity, high breaking current capability, and high resistance to electric arc corrosion and surface fusion welding.…”

“…Compared to traditional processing methods, metal-metal composite coatings made with CS may possess excellent corrosion and oxidation resistance because of the dense structure. For example, Bala et al 99…”

“…39,64,[67][68][69][70][71][72][73] The process parameters that influence these factors will affect the coating deposition. 6,[73][74][75][76][77][78][79][80][81][82][83][84][85][86][87] Up to now, CS has been used to fabricate a variety of coatings, including mostly elemental metals and alloys, but also composite coatings, providing corrosion resistance, 26,[88][89][90][91][92][93] wear resistance 21,[94][95][96] and high temperature resistance, [97][98][99] as well as functional coatings [100][101][102][103][104][105][106][107][108] for industrial applications. The detailed microstructure evolution in CS coatings have b...…”

“…This kind of coatings is widely used in high-temperature parts, such as aero engines, turbines and boilers. For examples, Ni-Cr oxidation resistant coatings for boilers,99…”

Performance of thermal-sprayed coatings to combat hot corrosion of coal-fired boiler tube and effect of process parameters and post-coating heat treatment on coating performance: a review

“…From Table 6, it is concluded that cold-sprayed Ni–50Cr and Ni– 20Cr–TiC–Re coatings on SA516 and T22 steel is a better option to provide maximum resistance against oxidation and hot corrosion, respectively [31,32].…”