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Solid particle erosion studies were conducted in simulated coal-fired boiler environment in order to compare the erosion behavior of three different types of detonation gun (D-Gun)-thermally-sprayed coating powders, i.e., WC-12%Co, Cr3C2-25%NiCr and Al2O3-13%TiO2 on ASTM A36 steel and bare ASTM A36 steel. Erosion studies were conducted by using an air jet erosion test rig at impact angles of 45°, 60° and 90°. During the erosion studies, weight loss and erosion rates in terms of volume loss (mm3/g) were determined by using an optical profilometer. WC-12%Co-coated specimens exhibited the behavior closer to the behavior of ductile materials, whereas Cr3C2-25%NiCr- and Al2O3-13%TiO2-coated specimens exhibited the typical behavior of brittle materials. All the three different types of D-Gun-sprayed coating powders had successfully protected the ASTM A36 steel from solid particle erosion at an impact angle of 45°. Out of the three different types of coatings, two coatings, i.e., WC-12%Co and Cr3C2-25%NiCr, had successfully protected the ASTM A36 steel from solid particle erosion at impact angles of 60° and 90°. This paper evaluates the solid particle erosion behavior of bare and coated ASTM A36 steel which will be helpful in choosing the suitable coating for induced draft fan applications.

PurposeThis paper aims to perform the solid particle erosion studies in simulated coal-fired boiler conditions with a view to compare the erosion behavior of two different types of detonation gun (D-Gun) sprayed cermet coating powders, that is, WC-12%Co and Cr3C2-25%NiCr on ASTM A36 steel and bare (uncoated) ASTM A36 steel.Design/methodology/approachErosion studies were performed using an air jet erosion test rig at impingement angles of 45°, 60° and 90°. During the erosion studies weight loss, erosion rates in terms of volume loss (mm3/g) and measurement of erosion profiles were determined using optical profilometer.FindingsBoth cermet coatings had successfully protected the ASTM A36 steel from erosion at impingement angles of 45°, 60° and 90°. In the case of bare ASTM A36 steel, the erosion rates were maximal at an impingement angle of 45° and minimal at an impingement angle of 90°, thus depicting the peculiar erosion behavior of ductile materials. WC-12%Co coated specimens exhibited erosion behavior that is closer to the behavior of ductile materials. Cr3C2-25%NiCr coated specimens exhibited the maximum erosion rate at an impingement angle of 90° and minimum at an impingement angle of 45°, hence depicting the typical behavior of brittle materials.Practical implicationsIt is expected that these results will contribute to the improvement of erosion resistance of induced draft fans, by the application of D-Gun sprayed WC-12%Co and Cr3C2-25%NiCr cermet coatings.Originality/valueThis paper evaluates the solid particle erosion behavior of bare and cermet-coated ASTM A36 steel which will be helpful in choosing the suitable cermet coating for induced draft fan applications.

Hardfacing is one of the adaptable methods that can build up the hard and wear resistant surface layer of different materials on the surface of substrate material. It helps them withstand wear, as well as prevent corrosion and high temperature oxidation. In the present investigation three different types of Fe–C–Cr based hardfacing electrodes with varying chemical compositions were deposited on ASTM A36 steel substrate by using manual metal arc welding (MMAW) process. ASTM A36 steel was selected as a base material after consulting with Pressure and Process Boilers, Saharanpur (India), which is a leading manufacturer of boilers. ASTM A36 steel is mostly used by this company for the production of induced draft fans. MMAW process with direct current constant current type power source was used to deposit the hardfaced layers of uniform quality. Straight polarity was used for MMAW process so that more of the arc heat should be concentrated on the electrode. The hardfaced samples were characterized using various characterization techniques and the results of the same were also outlined in the present investigation.

Erosion studies were performed in simulated coal-fired boiler conditions with a view to compare the erosion behaviour of two different types of detonation gun (D-gun) sprayed cermet coating powders, i.e., WC-12%Co and Cr3C2-25%NiCr on ASTM A36 steel and bare (uncoated) ASTM A36 steel. During the erosion studies weight loss, erosion rates in terms of volume loss (mm3/g) and measurement of erosion profiles were determined utilising optical profilometer. All the two different types of D-gun sprayed cermet coatings had successfully protected the ASTM A36 steel from erosive wear at impingement angles of 45o, 60o and 90o. In the case of bare ASTM A36 steel specimens the solid particle erosion rates were maximal at an impingement angle of 45o that was reduced at an impingement angle of 60o and minimal at an impingement angle of 90o that is the typical erosive wear behaviour of ductile materials. WC-12%Co coated specimens exhibited erosive wear behaviour that is closer to the behaviour of ductile materials. Cr3C2-25%NiCr coated specimens exhibited the maximum volume erosion rate at an impingement angle of 90o which was reduced at an impact angle of 60o and minimum at an impingement angle of 45o hence depicted the typical behaviour of brittle materials.

Surface modification techniques are used to enhance the service life of several engineering components by combating wear. Material loss due to wear in various industries is significantly high. Surfacing is a cost-effective and proven method of depositing protective coating. Research is going on over years to reduce the corrosion, erosion, and wear either in the form of using a new corrosion-, erosion-, and wear-resistant material or by improving these properties in the existing material by using surface modification techniques such as hardfacing and surface coating. The economic success of the hardfacing process depends on selective application of hardfacing material and its chemical composition for a particular application. In this paper, an attempt has been made to discuss the various types of surface modification techniques such as hardfacing and surface coating used for combating wear. Surface protection by different hardfacing techniques and surface coatings employed on the substrate surface of material by different methods and their advantages have been discussed.