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https://dspace.iiti.ac.in/handle/123456789/10436
Title: | Effect of process parameters of grit blasting on low carbon steel substrates in different environments |
Authors: | Tawade, Prathamesh Shembale, Suyog Kazi Sabiruddin [Guide] |
Keywords: | Mechanical Engineering |
Issue Date: | 20-May-2022 |
Publisher: | Department of Mechanical Engineering, IIT Indore |
Series/Report no.: | BTP620;ME 2022 TAW |
Abstract: | The adhesion of thermally sprayed coatings to their substrates is crucial to the performance of the coatings. Surface roughness and cleanliness are the most important parameters affecting the adhesion strength of the coatings. Grit blasting is commonly used for surface prepa ration prior to subsequent coating processes. This study aims to analyse the effect of grit blasting on the surface and sub-surface characteristics of mild steel substrates under dry and wet environments. Three types of wet environments were simulated - water, saline water, alcohol. The variation of surface roughness with grit size, standoff distance (SOD) and time was analysed under dry and wet environments. The nature of variation of roughness with the process parameters is observed to be similar under both dry and wet environments. A mathematical model was developed to estimate the increment in contact area for each surface condition. The optimal set of process parameter levels corresponding to the maximum con tact area were determined for each environment. Vickers micro-indentation hardness testing was performed on the cross section of grit blasted samples at various depths. The maximum hardness obtained near the grit blasted surface indicates the highest work hardening effect at the sub-surface zone. The influence of grit blasting on substrate hardening is found to decline with depth. Higher the work hardening occurring at the surface, higher is the estimated depth of the affected layer. Work hardening due to grit blasting is observed to be higher under dry conditions vis-à-vis wet conditions. X-Ray Diffraction (XRD) analysis was carried out over as-received grit blasted surfaces to identify the phases formed on the surface under different environments. Ferrite i.e. α-Fe (mostly observed in bulk steel material) is the dominant phase detected over grit blasted surfaces under both dry and wet environments. Significant surface contamination has been observed to take place in saline water environment. Oc currence of Al2O3 peaks in the diffraction patterns of surfaces grit blasted under all four environments suggests entrapment of alumina grit residues within the surface. On the basis of the relative intensity of Al2O3 peaks occurring in the diffraction patterns of the substrates, it has been argued that the proportion of grit residues entrapped over the grit blasted surface is the lowest when grit blasting is carried out in the alcoholic environment, suggesting some cleaning action of volatile environments. Sub-surface microstructure of grit blasted sam ples was evaluated using optical microscopy, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS) techniques. Sub-surface cracks are noticed to be substantial for samples grit blasted under dry conditions; sub-surface damage is appreciably lower for samples grit blasted under wet environments. SEM micrographs reveal significant grain elongation in the vicinity of the grit blasted surfaces; deformation ef fects of grit blasting fade out as one moves away from the grit blasted surfaces. EDS results are consistent with the XRD results i.e. the elements corresponding to the phases detected by XRD were detected by EDS as well. This research work attempts to determine the suitable combination of process parameter levels for performing grit blasting over low carbon steel substrates in different environments. Additionally, it also attempts to help understand the effect of those process parameters on the surface and sub-surface characteristics of the substrates. |
URI: | https://dspace.iiti.ac.in/handle/123456789/10436 |
Type of Material: | B.Tech Project |
Appears in Collections: | Department of Mechanical Engineering_BTP |
Files in This Item:
File | Description | Size | Format | |
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BTP_620_Prathamesh_Tawade_180005019_Suyog_Shembale_180003057.pdf | 3.15 MB | Adobe PDF | View/Open |
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