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Ternary shape memory alloys powder feedstock fabrication by advanced mechanical alloying
Regináč, Jan ; Moravčík, Igor (referee) ; Čížek, Jan (advisor)
Prášková metalurgie může být použita jako alternativní metoda pro výrobu slitin s tvarovou pamětí s Cu-bází. Tato metoda poskytla lepší výsledky, co se týče celkového složení a velikosti zrn, než tradiční metoda lití. V této práci byl aplikován proces mechanického legování k přeměně směsí základních prášků Cu-Al-Ni na mechanicky legované směsi. Cílem práce bylo nalezení optimálních parametrů pro výrobu nejvhodnějšího práškového prekurzoru určeného k dalšímu zpracování. SEM, EDX a XRD analýzy byly použity pro zjištění účinku změny parametrů na výslednou strukturu a na případnou tvorbu nových fází. Bylo ukázáno, že vysokoenergetické legování je vhodnou metodou pro výrobu takových prekurzorů. Na základě výsledků bylo zjištěno, že tuhý roztok mědi byl formován nezávisle na změně mlecích parametrů. Výsledky dále odhalily, že vysoký energetický vstup ve formě otáček a dlouhých mlecích časů, může způsobovat vznik amorfních fází.
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Preparation and properties of porous magnesium material
Ďubašák, Matej ; Kosár, Petr (referee) ; Březina, Matěj (advisor)
Magnesium is a lightweight metal suitable for various technical and biomedical applications due to its great strength-weight ratio and biocompatibility. The powder metallurgy (PM) of magnesium presents a modern method of porous magnesium processing, in which are reached specific mechanical properties influenced by high purity, material structure and controlled porosity during this process. This thesis deals with preparation and characterization of porous magnesium material which is prepared from a magnesium powder containing a particles with average size of 50 µm. The preparation process consists of powder pressing and sintering of green compacts. The properties of porous magnesium prepared by PM method depend on conditions of every individual process. The compaction pressure and sintering temperature were altered to optimize a preparation proces. There were examined mechanical properties (3 point bending, hardness) and optical properties (fractography and metallography). Obtained properties of porous magnesium prepared by PM were compared with technical literature.
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High speed steel milling cutters made by powder matallurgy
Svoboda, Martin ; Sámelová, Vendula (referee) ; Jaroš, Aleš (advisor)
Bachelor thesis is a research work describing milling cutters made of high speed steel by powder metallurgy (HSS PM milling cutters). In chapters one, two and three are generally described milling, high speed steels and powder metallurgy. In chapter four are introduced particular HSS PM milling cutters of a few producers. The summary contains mechanical properties of cutters and suitability for machining. It is focused on main type of HSS PM cutters, which are the end mills.
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On the development of technological properties of ferrite powder
Soviš, Jan ; Dvořák, Jaromír (referee) ; Píška, Miroslav (advisor)
This master’s thesis deals with production of ferrite cores by the powder metallurgy technology in EPCOS s.r.o. Šumperk. Special importance is given to powder compaction process through uniaxial cold pressing in a rigid die. The production company is introduced in the first part and is followed by a study of pressure propagation in a powder bed during uniaxial pressing, then the analysis of critical phases of compaction process in terms of green cracks and compact’s defects follows. Main test methods of compact’s green strength are also presented. Significant part of the master’s thesis deals with an analysis of a powder technological properties’ testing method. For that purpose, an instrumented compaction device called Powder Testing Center (PTC, KZK Powder Tech Corp.) is used. A new pressing tool of smaller diameter was made and mounted to the experimental press; also the testing technique, procedure and certificate of powder’s properties was slightly changed. Technological property called advanced compactibility of powder is introduced. Decision about suitability of powder for uniaxial pressing process is made upon the value of newly introduced coefficient of advanced compactibility . Compact’s green strength is evaluated by a proposed contract bend test method, which uses cylindrical-shaped testing pieces with high height-to-diameter ratio. The results from both testing methods show the impact of additional granulate adjustment on green strength and heterogeneity of density distribution along axial direction. Implementation of gained knowledge to production process led to more than 40 % cost savings in term 2/2016 – 4/2016 in comparison with term 8/2015 – 11/2015, because of lowering the number of scrap parts from KLY material due to crack reduction.
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Preparation and properties of bulk material from magnesium powder
Ruttkayová, Veronika ; Pacal, Bohumil (referee) ; Doležal, Pavel (advisor)
Diploma thesis focuses on preparation and characterization of bulk material prepared from pure magnesium powder. The topic includes all the parts of process of bulk material preparation, sintering at hot pressing, diffusion processes and structurally-mechanical properties with respect to final material porosity of the produced material. Thesis solving focuses on study and control of processes during bulk material preparation and description of the processes from physically-chemical point of view of the structure creation and final material properties.
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High-temperature embrittlement of 14%Cr ODS ferritic steel in liquid lead environment
Dohnalová, Eva ; Čelko, Ladislav (referee) ; Hadraba, Hynek (advisor)
The thesis deals with the high-temperature embrittlement of 14%Cr ODS ferritic steel in liquid lead environment. The 14%Cr ferritic ODS steel ODM401 manufactured by powder metallurgy technology was used as an experimental material. The effect of the long-term annealing, surface corrosion attack in the melt Pb and Pb-Bi on the microstructure and mechanical properties was described. The subsequent microstructural changes were evaluated by means of scanning electron microscopy and transmission electron microscopy The mechanical behaviour of the experimental material was proven by means of microhardness test, impact test and static tensile test. The fractographical evaluation of fracture surfaces were performed on all samples. The surface attack and outstanding microstructural ganges were found after the long-time exposition of the steel in Pb/Pb-Bi melts at temperature 550°C/1000h and 500°C/1000h respectively. The embrittlement of the steel after exposition in Pb/Pb-Bi melts was comparable to the embrittlement after high-temperature annealing of the steel at temperature 650°C/1000h.
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Biodegradable bone implants based on iron
Müller, Petr ; Kazda, Tomáš (referee) ; Sedlaříková, Marie (advisor)
The present work deals with the comparison of the properties of metallic biomaterials in terms of their suitability for use as a temporary metal implant. In the work is judged biocompatibility of materials, they are comparing the corrosion rates and the influence of additives in the iron alloy to change biocompatibility and corrosion rate. In a part of this work is suggesting a method of preparing biodegradable metallic samples with different alloying elements and determine the methods, processes and measuring the corrosion rates. Part of this work is the chapter dealing with the function and effect of iron in the human body and any complications that may occur when a surplus caused by the release of part of the implant during its degradation or corrosion products. The outcome of this work is sort of created an iron-based samples in terms of their electrochemical corrosion potential, corrosion rate of samples exposed in various corrosive solutions, spectroscopic elemental analysis and outputs from the microscopic observation of the structures.
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