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Surface coatings of medium and high entropy alloy prepared by the cold-spray method
Vražina, Tomáš ; Adam, Ondřej (referee) ; Moravčík, Igor (advisor)
This bachelor thesis investigated coating of the CoCrNi (Medium entropy) alloy deposed onto austenitic steel substrate. The main objectives were characterization and analysis of sprayed deposition before and after heat treatment. The thesis was divided into 2 main parts. The theoretical part provided general information about alloy manufacturing, properties, and the method of its consolidation. The experimental part provided electron microscopy analysis including, an EDS, a porosity analysis and microhardness testing. Its results were then discussed on the base of the information gathered in the theoretical part. The results showed that the deposed layer was stable and there was no sign of material decohesion. The coating showed low porosity which was later successfully lowered by heat treatment. EDS proved that the coating was not entirely homogenous. The conclusion summarized the results achieved in the practical part.
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The role of thermal spray parameters on structure and properties of cermet coatings
Vražina, Tomáš ; Čelko,, Ladislav (referee) ; Šulák, Ivo (advisor)
The diploma thesis investigates the influence of thermal spray process parameters on the properties of composite coatings, specifically WC-CrC-Ni and WC-Co-Cr coatings deposed onto an austenitic steel substrate. The main objectives were characterization of sprayed deposition and creation of process maps. The theoretical part included the most important details about the manufacturing process, properties, consolidation and application of cermet materials. The methodical part is devoted to a description of analytical methods and devices used for the characterization of coatings microstructure and its mechanical properties. The practical part provides information acquired from analytical devices. It contains details about surface roughness, hardness, porosity, indentation modulus, corrosion potential and corrosion current density. The chemical composition of coatings and powder mixtures was analyzed by energy dispersive spectroscopy (EDS). For more accurate determination of developed phases X-ray diffraction was used. During the coatings characterization various procedures were developed. It is expected that these procedures would be implemented in another optimization of spraying conditions. Results obtained in the practical part were discussed in discussion and compared with the results from several research studies. Conclusions summarize results obtained in practical part.
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INFLUENCE OF THE DEPOSITION PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF HVOF SPRAYED WC-CRC-NI COATING
Vražina, Tomáš ; Šulák, Ivo ; Poloprudský, Jakub ; Zábranský, K. ; Gejdoš, P. ; Hadraba, Hynek ; Čelko, L.
This paper investigates the influence of thermal spray parameters of the high-velocity oxygen fuel (HVOF) process on the properties of cermet coatings prepared from commercially available Amperit 551 WC-CrC-Ni powder. Three different processing parameters were applied to optimize the production process with the aim to achieve preeminent mechanical properties and fully dense material without microstructural defects. The deposition was carried out by a GLC5 gun. The velocity and temperature of powder particles in the spray stream were monitored by Accuraspray Tecnar diagnostic tool. The quality of deposited coatings was analyzed by means of light microscopy, scanning electron microscopy, and X-ray diffraction. The chemical composition of the used powder and sprayed WC-CrC-Ni coating was determined by energy dispersive spectroscopy. It was found that the spray parameters have a negligible effect on the resulting microstructure and phase composition of the coating. However, the porosity and surface roughness were significantly affected by the variation in process parameters. To assess the basic mechanical properties of HVOF sprayed coating instrumented Vickers hardness measurements were utilized. The coating hardness reached mean values over 1400 HV 0.1 and the indentation modulus varied from 152-279 GPa.
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The role of thermal spray parameters on structure and properties of cermet coatings
Vražina, Tomáš ; Čelko,, Ladislav (referee) ; Šulák, Ivo (advisor)
The diploma thesis investigates the influence of thermal spray process parameters on the properties of composite coatings, specifically WC-CrC-Ni and WC-Co-Cr coatings deposed onto an austenitic steel substrate. The main objectives were characterization of sprayed deposition and creation of process maps. The theoretical part included the most important details about the manufacturing process, properties, consolidation and application of cermet materials. The methodical part is devoted to a description of analytical methods and devices used for the characterization of coatings microstructure and its mechanical properties. The practical part provides information acquired from analytical devices. It contains details about surface roughness, hardness, porosity, indentation modulus, corrosion potential and corrosion current density. The chemical composition of coatings and powder mixtures was analyzed by energy dispersive spectroscopy (EDS). For more accurate determination of developed phases X-ray diffraction was used. During the coatings characterization various procedures were developed. It is expected that these procedures would be implemented in another optimization of spraying conditions. Results obtained in the practical part were discussed in discussion and compared with the results from several research studies. Conclusions summarize results obtained in practical part.
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Surface coatings of medium and high entropy alloy prepared by the cold-spray method
Vražina, Tomáš ; Adam, Ondřej (referee) ; Moravčík, Igor (advisor)
This bachelor thesis investigated coating of the CoCrNi (Medium entropy) alloy deposed onto austenitic steel substrate. The main objectives were characterization and analysis of sprayed deposition before and after heat treatment. The thesis was divided into 2 main parts. The theoretical part provided general information about alloy manufacturing, properties, and the method of its consolidation. The experimental part provided electron microscopy analysis including, an EDS, a porosity analysis and microhardness testing. Its results were then discussed on the base of the information gathered in the theoretical part. The results showed that the deposed layer was stable and there was no sign of material decohesion. The coating showed low porosity which was later successfully lowered by heat treatment. EDS proved that the coating was not entirely homogenous. The conclusion summarized the results achieved in the practical part.
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