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5724 |
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Friday, June 09, 2017, Hall 28 11:40 AM Cold Gas Spraying III |
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Development of high-performance cols-sprayed nano-structured NI-20Cr coatings for hash enviroment of power plant boilers |
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Manoj Kumar* / CGC College of Engineering Landran, India Harpreet Singh/ Indian Institute of Technology Ropar, India Narinder Singh/ Indian Institute of Technology Ropar, India N.M. Chavan/ International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), India S. Kumar/ International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), India S.V. Joshi/ International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), India |
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In the current work, Ni-20Cr coatings have been developed for potential use in harsh environments of power plant boilers. A pre-synthesized Ni-20Cr nanocrystalline powder was deposited on SA 516 boiler steel using cold-spray process. The high temperature oxidation behavior of the coating was investigated under cyclic conditions at 900° C for 50 cycles, so as to understand the kinetics of oxidation. Moreover, high temperature erosion-corrosion (E-C) behaviour of the coating was ascertained under cyclic conditions in an actual boiler at 740 ± 10°C for 1500 hours. The oxidized and eroded-corroded samples were characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), and X-ray mapping analyses. The microhardness, oxidation and E-C data for the developed coating was compared with an earlier reported cold-spray Ni-20Cr coating, which was developed by using a commercially available micron-sized Ni-20Cr powder. The results showed that the developed coating was found to have 33% high microhardness in comparison with the microstructured Ni-20Cr coating. The oxidation and E-C rates of the steel were found to decrease significantly after the application of the developed coating by 89% and 68% respectively. Moreover the nanostructured coating outperformed the corresponding micro-structured Ni-20Cr coating with regard to high temperature oxidation and E-C resistance to boiler steel by a significant fraction. The investigated coating was found to have oxidation protective oxides such as Cr2O3 and NiO in its oxide scale and was found to be spallation-free. |