|
| |
|
|
Optimization of fabrication technology and defect detection for ceramics structures
Chyťa, Filip ; Otáhal, Alexandr (referee) ; Skácel, Josef (advisor)
This work deals with the problems of defects in ceramics structures and packages, their detection and subsequent optimization of the manufacturing process in order to eliminate these defects. The first chapter summarizes ceramic materials in elec-trical engineering and deals specifically with Al2O3 and material GRANNALOX 9620 F and optimization of its production profile. The second chapter deals with preparation of the ceramic powder and its subsequent processing. The third chap-ter deals with detection of defects in the thus formed ceramic packages, testing their electrical, thermal and mechanical makings. In the next chapter I deal with my workflow, which I used in the production of packages, the way of production and testing of packages, including comparison of their makings.
|
|
|
Study of transition from open to closed porosity stage during sintering of advanced ceramic materials
Spusta, Tomáš ; Pouchlý, Václav (referee) ; Maca, Karel (advisor)
Lisovanie za tepla (HIP) je pokročilá technológia pre výrobu plne hutných keramických materiálov, ktoré majú množstvo štruktúrnych (napr. rezné nástroje), biologických (napr. implantáty hutných kostí a kĺbov) alebo funkčných (napr. transparentné štíty a okná) aplikácií. Pre úspešné použitie tejto technológie je potrebné, aby predspekané vzorky boli plynotesné, teda bez otvorených pórov. Výskum zaoberajúci sa premenou otvorených pórov na uzatvorené je preto veľmi dôležitý, avšak iba málo publikovaný v odbornej literatúre. Preto bolo experimentálne a teoretické štúdium tohto javu hlavným cieľom diplomovej práce. Analýzy teoretických modelov ukazujú, že transformácia z otvorenej na uzatvorenú pórovitosť je materiálová charakteristika, ktoré sa mení iba s dihedrálnym uhlom, nezávisle na veľkosti častíc prášku alebo na spôsobe tvarovania a nastáva od 92.6% t.d. do 93.7% t.d pre daný materiál (oxid hlinitý, oxid zirkoničitý a horečnato-hlinitý spinel). Tieto teoretické výpočty boli porovnané s experimentálnymi dátami z literatúry a dátami z experimentálnej časti diplomovej práce s úspešnou zhodou pre kubické systémy (spinel a kubický oxid zirkoničitý). Výsledky experimentov s oxidom hlinitým boli v dobrej zhode s experimentálnymi dátami publikovanými v literatúre, ale boli vyššie ako teoretické hodnoty. Na objasnenie týchto odlišností bolo vytvorených niekoľko hypotéz a tiež boli navrhnuté spôsoby riešenia tejto témy.
|
|
|
Cutting ceramics and its effective use
Heča, Jan ; Sámelová, Vendula (referee) ; Humár, Anton (advisor)
Thesis dealing with cutting ceramics and its efficient use. Introduction describes the general characteristics of the cutting of ceramics, its history and development and production of various kinds. This section describes the mechanical and physical properties with potential application in machining. The se-cond part is an overview of cutting-frame in the range of selected world leaders. Ano-ther section focuses on general assessment of the power of cutting tools and other ma-terials comparison. The fourth part, is comparing the working conditions of producers and tools intended for cutting.
|
|
|
Cutting ceramics and its effective use
Heča, Jan ; Prokop, Jaroslav (referee) ; Humár, Anton (advisor)
Thesis dealing with cutting ceramics and its efficient use. Introduction describes the general characteristics of the cutting of ceramics, its history and development and production of various kinds. This section describes the mechanical and physical properties with potential application in machining. The se-cond part is an overview of cutting-frame in the range of selected world leaders. Ano-ther section focuses on general assessment of the power of cutting tools and other ma-terials comparison. The fourth part, is comparing the working conditions of producers and tools intended for cutting.
|
|
|
Two-step sintering of advanced ceramic materials with various crystal structures
Žalud, Pavel ; Trunec, Martin (referee) ; Maca, Karel (advisor)
The influence of Two-Step Sintering (TSS) process on the final microstructure of oxide ceramics materials with two different crystal structures was studied. Tetragonal zirconia (stabilized with 3mol%Y2O3, particle size 90nm and 140nm ) and cubic zirconia (8mol%Y2O3, 70nm) powders were cold isostatically pressed and pressure less sintered with different heating schedules. The microstructures achieved with TSS method were compared with microstructures achieved with conventional Single-Step Sintering schedule (SSS). The results showed that the efficiency of the TSS of these oxide ceramics was more dependent on their crystal structure than on their particle size and green body microstructure. The method of TSS brought only negligible improvement of the microstructure of tetragonal zirconia ceramics. On the other hand, TSS was successful in the sintering of cubic zirconia ceramics; it led to a decrease in grain size by a factor of 2.
|
|
|
Cutting ceramics and its effective use
Kavalír, Vít ; Sedlák, Josef (referee) ; Humár, Anton (advisor)
Master’s thesis are concerned with the cutting ceramic materials and its ef-fective usage. The first part of the thesis is focused on the general properties of the cutting ceramics, its history, development, production and description of the various types. This part includes as well a description of the mechanic-physical properties and the potential of the usage for machining. The second part of the work solves the general evaluation of the cutting power. The main issue in the next part is the identification of cutting ceramics range and the selection accor-ding to main world producers. The fourth part deals with the assessments and the comparison of the working conditions for different types of the machined ma-terials. The technical economic assessment shows the potentials in the total pro-duction costs reduction.
|
|
|
Cutting ceramics and its effective use
Fialová, Kateřina ; Prokop, Jaroslav (referee) ; Humár, Anton (advisor)
The diploma work is focused on the ceramic tool materials and its effective use. The introductory part of the work contains the detail characteristic of the ceramic tool materials from the point of view of their dividing, physic-mechanical propertis, production methods and marking. The main part of the work is focused to judging of the ceramic portion at the production assortment of the top World producers of tool materials and to evaluation of cutting ability of the particular materials of these producers. The detail analysis of recommended cutting conditions, which is aimed to an effective use of the ceramic materials, had been worked up for this purpose. The technical economic analysis confirms, that the present effective aplications of ceramic are limited only for specific cases of machining cast irons, steels and alloys.
|
|
|
Grain growth kinetics study of advanced oxide ceramic materials
Kazda, Adam ; Kachlík, Martin (referee) ; Pouchlý, Václav (advisor)
The goal of this work was to study the grain growth kinetics of five different materials: tetragonal ZrO2 (doped 3mol.% Y2O3 and particle size 80 nm), two cubic ZrO2 (doped 8 mol.% Y2O3 and particle sizes 80 and 140 nm) and two hexagonal Al2O3 (with particle sizes 100 and 240 nm). These ceramic powders were isostatically pressed and then they were isothermally sintered at 3 different temperatures for 1-60 hours. The biggest coarsening was discovered during temperature increase to sintering temperature. The dwelt at sintering temperature was not so important for coarsening. The activation energy of grain growth QG, growth exponent n and kinetic constant k0 were discovered for four materials. The activation energy of grain growth was 511±49 kJ/mol for tetragonal ZrO2, 645±84 kJ/mol for cubic ZrO2 a 428±75 kJ/mol a 606±24 kJ/mol for Al2O3. Possibility of kinetic window of sintering process for cubic ZrO2, tetragonal ZrO2, and Al2O3 with particle size 240 nm (doped MgO) were discovered by comparison of established activation energy of grain growth QG with activation energy of sintering QS from literature. Kinetic window of sintering process wasn’t found for high purity alumina with particle size 100 nm.
|
|
|
Cutting ceramics
Maříková, Petra ; Dvořák, Jaromír (referee) ; Humár, Anton (advisor)
Bachelor thesis deals with topic of cutting ceramics. In the first part is given a basic distribution of cutting materials and their general characteristics. The second part is focused on itself cutting ceramics, its history, production, distribution and mechanical and physical properties. In the third part is discribed assortment Ceramtec, Iscar, Kennametal, Sandvik-Coromant, Saint-Gobain Advanced Ceramics.
|
guest ::
