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Properties of quasicrystal-reinforced high entropy alloys
Adami, Martin ; Tesař,, Tomáš (referee) ; Čížek, Jan (advisor)
This diploma thesis deals with the processing of the high-entropy alloys with the addition of quasicrystals by the spark plasma sintering method. The aim of this thesis is to evaluate the influence of quasicrystals content on the microstructure and wear resistance. The literature review part is divided into several section. The first part is an overview of high-entropy alloys and quasicrystals, including their properties and production methods. The next part pertains to spark plasma sintering and the wear phenomenon. In the experimental part, spark plasma sintering compacts were produced at 1100 °C and an analysis was performed using scanning electron microscope as well as X-ray diffraction and their tribological properties were measured by the pin-on-disc method. It was found that increasing the content of quasicrystals triggered an improvement in the compacts’ wear resistance.
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Effect of modification of HVOF sprayed alloy NiCrBSi by electron beam on its structure
Pongrácz, Jakub ; Havlík, Petr (referee) ; Foret, Rudolf (advisor)
This thesis deals with surface re-melting by electron beam of thermal sprayed material NiCrBSi by method HVOF. The microstructure, chemical and phase composition, hardness and abrasive wear resistance were evaluated in depending on the electron beam parameters and modes of the electron beam 6-poinst and line. Observed microstructure was better after both methods of re-melting. The splats were not observed, coating porosity decreased and structure was more homogenous. Structure and phase analysis was acquired by light microscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction. A small change in hardness between modes of re-melting was observed, but measured hardness was higher than in sample without re-melting. Similar results were observed for abrasion resistance.
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High-alloyed cast irons Ni-resist and treir properties
Matulová, Anna ; Záděra, Antonín (referee) ; Kaňa, Václav (advisor)
This master’s thesis deals with high-alloyed Ni-Resist cast irons and their properties. The theoretical part describes their chemical composition and individual elements from which are these cast irons composed, their characteristic properties and examples of use in practice. Furthermore, the work focuses on the wear of materials, especially on abrasive wear, because Ni-Resist casts iron exhibit a number of specific properties, such as corrosion resistance, refractoriness and heat resistance and also abrasion resistance, on which is this thesis focused. Attention is also paid to other abrasion resistant materials, because specimens from different materials are compared in the practical part in order to find a more suitable material for the production of plate castings into the shakeouts.
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Manufacture and properties of wear resistant chromium cast irons
Klemsa, David ; Kaňa, Václav (referee) ; Záděra, Antonín (advisor)
This bachelor thesis is focused on the issue of properties, possibilities of influencing properties, production and use of high-chromium cast iron. For better understanding of this specific topic, some attention is paid to white cast iron generally. The work describes the way of gaining white cast iron and structural components occurring in white cast irons. Factors influencing the structure of white cast irons are discussed in more details – the chemical composition and heat treatment. The structure of cast iron determines its properties. The knowledge about the possibilities of influencing the structure is important to achieve the desired properties. Attention is also paid to the matrix structure and the types and morphology of carbides.
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Properties of quasicrystal-reinforced high entropy alloys
Adami, Martin ; Tesař,, Tomáš (referee) ; Čížek, Jan (advisor)
This diploma thesis deals with the processing of the high-entropy alloys with the addition of quasicrystals by the spark plasma sintering method. The aim of this thesis is to evaluate the influence of quasicrystals content on the microstructure and wear resistance. The literature review part is divided into several section. The first part is an overview of high-entropy alloys and quasicrystals, including their properties and production methods. The next part pertains to spark plasma sintering and the wear phenomenon. In the experimental part, spark plasma sintering compacts were produced at 1100 °C and an analysis was performed using scanning electron microscope as well as X-ray diffraction and their tribological properties were measured by the pin-on-disc method. It was found that increasing the content of quasicrystals triggered an improvement in the compacts’ wear resistance.
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High-alloyed cast irons Ni-resist and treir properties
Matulová, Anna ; Záděra, Antonín (referee) ; Kaňa, Václav (advisor)
This master’s thesis deals with high-alloyed Ni-Resist cast irons and their properties. The theoretical part describes their chemical composition and individual elements from which are these cast irons composed, their characteristic properties and examples of use in practice. Furthermore, the work focuses on the wear of materials, especially on abrasive wear, because Ni-Resist casts iron exhibit a number of specific properties, such as corrosion resistance, refractoriness and heat resistance and also abrasion resistance, on which is this thesis focused. Attention is also paid to other abrasion resistant materials, because specimens from different materials are compared in the practical part in order to find a more suitable material for the production of plate castings into the shakeouts.
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Effect of modification of HVOF sprayed alloy NiCrBSi by electron beam on its structure
Pongrácz, Jakub ; Havlík, Petr (referee) ; Foret, Rudolf (advisor)
This thesis deals with surface re-melting by electron beam of thermal sprayed material NiCrBSi by method HVOF. The microstructure, chemical and phase composition, hardness and abrasive wear resistance were evaluated in depending on the electron beam parameters and modes of the electron beam 6-poinst and line. Observed microstructure was better after both methods of re-melting. The splats were not observed, coating porosity decreased and structure was more homogenous. Structure and phase analysis was acquired by light microscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction. A small change in hardness between modes of re-melting was observed, but measured hardness was higher than in sample without re-melting. Similar results were observed for abrasion resistance.
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Mechanical properties of plasma sprayed layers of NiAl10 and NiAl40 on AZ91 alloy
Kubatík, Tomáš František ; Brodil, R. ; Ctibor, Pavel ; Průša, F. ; Brožek, Vlastimil
In this work, plasma coatings of NiAl10 and NiAl40 on magnesium alloy AZ91 substrate were prepared by the hybrid plasma spraying system WSP®-H 500. The both plasma sprayed coatings of NiAl10 and NiAl40 have metallurgical bond. The thicknesses of microstructures in the cross-section of NiAl10 and NiAl40 plasma sprayed coatings prepared by 9 passes were 374 and 440 μm respectively. Adhesion test of plasma sprayed layers was performed using a modified ASTM C 633 standard. The tensile adhesion strength values are 24.7 MPa for NiAl10 coatings and 12.3 MPa for NiAl40 coatings. Abrasion resistance according to Slurry Abrasion Response (SAR) test of NiAl40 layers had similar values (0.12 g/cm2)in a comparison with the uncoated AZ91 (0.126 g/cm2). Layers NiAl10 had greater weight losses (0.175 g/cm2) than uncoated AZ91. Microhardness of plasma coating of NiAl40 is several times greater than microhardnesses of plasma coating of NiAl10 and uncoated substrate AZ91
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Manufacture and properties of wear resistant chromium cast irons
Klemsa, David ; Kaňa, Václav (referee) ; Záděra, Antonín (advisor)
This bachelor thesis is focused on the issue of properties, possibilities of influencing properties, production and use of high-chromium cast iron. For better understanding of this specific topic, some attention is paid to white cast iron generally. The work describes the way of gaining white cast iron and structural components occurring in white cast irons. Factors influencing the structure of white cast irons are discussed in more details – the chemical composition and heat treatment. The structure of cast iron determines its properties. The knowledge about the possibilities of influencing the structure is important to achieve the desired properties. Attention is also paid to the matrix structure and the types and morphology of carbides.
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Study of fracture toughness and wear resistance of thin MoBC coating under dynamic conditions
Buršíková, V. ; Grossman, Jan ; Fořt, Tomáš ; Souček, P. ; Zábranský, L. ; Buršík, Jiří ; Vašina, P. ; Dupák, Libor ; Sobota, Jaroslav
The aim of the present work was to study the mechanical properties of thin amorphous MoBC coatings and MoBC coatings consisting of nanocrystalline Mo2BC embedded in amorphous MoBC matrix. The hardness of the amorphous MoBC coatings (20 GPa) is comparable with the common amorphous diamond-like carbon coatings, however their elastic modulus as well as fracture toughness and ductility are significantly higher. Magnetron sputtering of three targets, B4C, C and Mo, for MoBC was used for coatings preparation. The aim of this work was to study the mechanical and tribological properties of MoBC coatings deposited on high speed steel substrate. The classification of MoBC coatings was performed using an impact tester in a dynamic mode and enabled us to predict the limit load causing the coating destruction.
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