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contributor.authorSatapathy, Alok-
contributor.authorMishra, S C (Guide)-
identifier.citationThermal Spray Coating of Redmud on Metals, Doctoral Thesis, Nov 2005, P 173en
descriptionCopyright for this thesis belongs to National Institute of Technology, Rourkela, Indiaen
description.abstractRed mud emerges as the major waste material during production of alumina from bauxite by the Bayer’s process. It comprises of oxides of iron, titanium, aluminium and silica along with some other minor constituents. The present investigation explores the coating potential of this industrial waste. It envisages the processing and characterization of a series of plasma sprayed coatings made with red mud and red mud pre-mixed with different proportions of fly ash and powders of aluminium and carbon. These materials do not belong to the so called “plasma sprayable” category. They have been deposited on aluminium, copper, mild steel and stainless steel substrates by atmospheric plasma spraying. The coatings are characterized to evaluate their potential as wear resistant coatings. Micro-structural characterization of the coatings has been carried out using scanning electron microscopy, x -ray diffraction and image analysis technique. It is found that red mud is eminently coatable. The coatings possess good adhesion strength, hardness and reasonable porosity. With addition of fly ash and aluminium to red mud, the efficiency of deposition and coating properties such as adhesion, hardness are substantially improved. Premixing of carbon also favours deposition and results in better coating hardness. Due to certain phase transformations and inter-oxide formation during plasma spraying, changes in the coating characteristics are observed. The erosion wear performance of these coatings is evaluated using a solid particle erosion test rig. Red mud coatings offer an attractive erosion wear resistance, which further improves on addition of fly ash and aluminium to the feed stock. Statistical analysis of the experimental results using techniques like fractional factorial test and Taguchi experimental design is presented. Spraying parameters such as plasma arc current, torch input power, arc voltage, surface roughness of the substrate are identified as the significant factors affecting the efficiency of coating deposition. A prediction model using artificial neural networks is also employed to simulate property-parameter correlations and a fairly good agreement in the experimental and predicted values is obtained. This analysis makes it clear that with an appropriate choice of processing conditions a sound and adherent ceramic coating is achievable using industrial wastes like red mud and fly ash.en
format.extent3947206 bytes-
publisherNational Institute of Technology, Rourkelaen
titleThermal Spray Coating of Redmud on Metalsen
Appears in Collections:Thesis (Doctor of Philosophy)

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