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Author: search.filters.author.Somasundaram, B.Subject: search.filters.subject.HVOF

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    Hot Corrosion Behaviour of HVOF Sprayed (Cr3C2–35 % NiCr) + 5 % Si Coatings in the Presence of Na2SO4–60 % V2O5 at 700 °C
    (Springer, 2015) Somasundaram, B.; Kadoli, R.; Ramesh, M.R.
    The hot corrosion behavior of high velocity oxyfuel sprayed (Cr3C2–35 % NiCr) + 5 % Si coatings on three substrate alloys of SA213-T22, MDN-310 and Superfer 800 H was investigated. The as-sprayed coatings are characterized with respect to microstructure and mechanical properties. Thermocyclic hot corrosion studies were performed in a molten salt environment of Na2SO4–60 % V2O5 for 50 cycles at 700 °C. Thermogravimetric technique was used to establish the kinetics of hot corrosion of uncoated and coated steels. It was observed that the coated steel showed better hot corrosion resistance than the uncoated steels. The coated steels follow the parabolic rate law of oxidation and the parabolic rate constant values are appreciably lower in comparison to the uncoated steels. The coated steels showed slow oxidation kinetics which indicated that the reaction rate is diffusion limited. The oxides of Cr2O3 and SiO2 formed on the outermost surface of the coatings are found to be passive in the molten NaVO3 melt. © 2014, The Indian Institute of Metals - IIM.
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    High temperature corrosion behaviour of HVOF sprayed WC-CrC-Ni coatings
    (Inderscience Publishers, 2016) Somasundaram, B.; Kadoli, R.; Ramesh, M.R.; RAMESH, C.S.
    The present work aims to study the hot corrosion resistance of high velocity oxy-fuel (HVOF) sprayed WC-CrC-Ni coating developed on three types of boiler tube materials such as SA213-T22, MDN-310 and Superfer 800 H steels. Hot corrosion studies were conducted in a molten salt environment of Na2SO4-60%V2O5 at 700°C and thermogravimetric analysis was used to establish kinetics of corrosion. Corrosion kinetics of coated steels followed nearly parabolic behaviour and showed a lower corrosion rate in comparison to uncoated alloys. It is concluded that corrosion is restricted to the external surface of the coating and the formation of thick scale composed of oxides of Cr, Ni and their spinel oxides, acts as a diffusion barrier to the transportation of corrosive species into the coating. The carbides of tungsten and chromium uphold the strength of the coating. © © 2016 Inderscience Enterprises Ltd.
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    Erosion behaviour of HVOF sprayed (CR3C2-35%NICR) +5%Si coatings
    (IAEME Publication, 2017) Somasundaram, B.; Jegadeeswaran, N.; Madhu, G.; Ramesh, M.R.
    In the present study, (Cr3C2-35%NiCr) +5%Si cermet coatings were deposited on a Fe based T22 steel substrate to reduce the damage caused by erosion boiler applications. Erosion studies were conducted on uncoated as well as HVOF coated steels. The erosion experiments were carried out using an air-jet erosion test rig according to ASTM G-76 standard at a velocity of 30 m/s and at different impingement angles of 30°, 60° and 90°. Silica sand particles of size ranging between 150 to180 ?m were used as erodent. Analysis of weight-loss data and volumetric steady state erosion rates for different coatings and substrate alloys are evaluated. The bare T22 steel followed ductile erosion mode where as (Cr3C2-35%NiCr) +5%Si coating exhibited mixed behaviour respectively.
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    Microstructure characteristics and properties of WC-CrC-Ni HVOF coating for boiler tube steel
    (Elsevier Ltd, 2022) Somasundaram, B.; Patil, V.G.; Ramesh, M.R.; Kandaiah, S.; Jegadeeswaran, N.
    In the present work, the characterization of HVOF sprayed WC-CrC-Ni coating on three bare alloys of MDN-310, SA213-T22, and Superfer 800H was investigated with the HVOF technique. The microstructure of the specimens were examined using a range of characterization techniques including XRD analysis, SEM, and EDS interfaced to SEM. The as-sprayed coatings are characterized with respect to microstructure and mechanical properties. The porosity, surface roughness, coating thicknesses, density, and bond strength of coatings have been also evaluated. © 2021