National Repository of Grey Literature 28 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Influence of CaO Content on Specific LCC, ULCC and NCC Properties
Zemánek, David ; Nevřivová, Lenka
Castables are widely used refractory materials with variable applications. Three types of castables (low cement, ultra-low cement and no cement) were tested to compare their specific properties. Also, corrosion resistance test as an important factor influencing castables design was carried out. Potassium carbonate was used as a corrosive medium using static crucible method. The corrosion mechanisms were evaluated by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The results confirmed that the presence of higher amount of calcium oxide from the Calcium Aluminate Cement (CAC) leads to formation of calcite and anorthite. The corrosion resistance was improved with decreasing or replacing the hydraulic bond.
Fireclay Grog with a High Alumina Content
Mezulianík, Tomáš ; Tvrdík,, Lukáš (referee) ; Nevřivová, Lenka (advisor)
Special refractory grog with increased alumina content are not currently produced in the Czech Republic. The price of these grogs produced abroad is high, so there is an effort to produce grogs using domestic waste fractions of claystones, which have been stored for decades. The theoretical part of the thesis describes the current results and experience with the processing of fine waste parts of claystone W super and BVP. Suitable raw materials for the preparation of grog with an increased content of alumina are characterized. In the experimental part of the thesis is verified the possibility of production of grogs with increased content of Al2O3 according to the proposed prescriptions.
Brick Dust Arising During Grinding of Burnt Brickwork and Possibilities of its Utilization
Kocmánek, Tomáš ; Sokolář, Radomír (referee) ; Nevřivová, Lenka (advisor)
The diploma thesis focuses on the brick dust arising during grinding of burnt brickwork and the possibilities of its utilization. In the theoretical part origin and basic properties of brick dust is described. Some published results of research on the potential utilization of brick dust in various industries are presented here. Also proposal of utilization of brick dust in the ceramic industry is presented. In the practical part two ceramic raw materials and the two brick dust with different granulometry arising during grinding of burnt brickwork (made from these two ceramic raw materials) were selected. The effect of the addition of brick dust to the ceramic raw materials on the physical - mechanical properties of ceramic body after sintering was investigated.
Diagnostic Methods Suitable for Monitoring of Drying Process of Brick Product
Sarvaš, Ondřej ; Sokolář, Radomír (referee) ; Nevřivová, Lenka (advisor)
This work deals with the study of diagnostic methods suitable for monitoring of the drying process of brick raw materials. Based on the extensive literature search, several parameters are selected, which are appropriate to monitoring during drying. In addition, a methodology for measuring these selected parameters is proposed. In the experimental part, the use of all described methods is gradually verified on the brick raw material with and without shortening additive (also known as grog). Was carried out: measurement of the surface temperature in the climatic chamber, determination of humidity distribution in the sample, determination of moisture diffusivity, determination of tensile strength, determination of ultrasonic wave velocity and determination of dynamic E-modulus of elasticity. Results of experiments and the gained experiences show, that at least two of the above-mentioned monitoring methods are very appropriate and beneficial – determination of moisture diffusivity and determination of tensile strength. In the work was described in detail the procedure of determination of moisture diffusivity of material. The dependence of moisture diffusivity on the moisture content of the dried material, has been described. Also, differences between raw material with grog and without grog has been described. As part of the practical verification of the experiment designed to determine the tensile strength at different humidity levels of test samples. A new shape of the test specimens and a new device were designed to allow them to be attached to a hydraulic press. The results of this work show that the tensile strength of the ceramic green bodies is primarily dependent on the moisture content of the material. The type of raw material almost does not affect the tensile strength.
Mullite Refractory Grog
Zemánek, David ; Tvrdík,, Lukáš (referee) ; Nevřivová, Lenka (advisor)
Refractory aggregate manufactured from common clays, claystones and shales in Czech Republic are mostly classified as fireclay. For specific applications are these grogs not suitable and there is a need to use grogs with higher content of alumina oxide. Theoretical part of this thesis is focused on the mineral mullite, which is one of the basic minerals in Al2O3 - SiO2 system. Research is focused on methods of mullite production, manufacture of recfractory grog and new possibilities in modification of current raw materials. In experimental part is carried out a verification of possible production of grogs with increased alumina content according to the designed composition.
Mineralogical composition of silica brick.
Pospíšil, Dušan ; Kotouček, Miroslav (referee) ; Nevřivová, Lenka (advisor)
This Bachelor´s thesis deals with the mineralogical composition of dense silica bricks. Silica bricks is a siliceous refraktory material that contains up to 99% of silicon dioxide, which is used mainly for the construktion of coke oven batteries, glass furnaces and heaters of blast-furnace wind. The main emphasis in case of silica bricks is put on the content of crystalline phases, which are the residual untransform quartz, tridymite, cristobalit and glass phase. These stages affect the resulting properties of dinas substantially. The main goal of this Bachelor´s thesis is to evaluate the impact of firing on the mineralogical composition of silica bricks and to its dilation at elevated temperatures.
Color Changing of the Ceramic brick.
Kocmánek, Tomáš ; Zach, Jiří (referee) ; Nevřivová, Lenka (advisor)
The bachelor’s thesis is focused on color correction of brick body. There are examples of pigments commonly used in various industrial fields, as well as studies on the use of waste products as additives in brickmaking industry, altering, among other things, the color of the brick body. In the experimental part of the thesis the effect of three selected ferric pigments and two selected correction clays on the color and selected physico-mechanical properties of the brick body was investigated.
Dense Mullite Aggregate
Mezulianík, Tomáš ; Tvrdík,, Lukáš (referee) ; Nevřivová, Lenka (advisor)
Refractory aggregate based on aluminosilicate are manufactured by firing clays, claystones or shales. The firing takes place in rotary or blast furnaces. However, when manufacturing the special refractory materials, we can not do it without special aggregate with higher content of Al2O3. Theoretical part of this thesis is aimed on the description of mineral mullite and mullite refractory aggregate, their method of production and raw material basis. The research of mullite aggregate on the market and their application in the refractory industry. In conclusion of the study, an experiment was performed for the production of special aggregate with increased alumina content according to the proposed prescriptions
No-Cement Corundum Refractory Castables.
Novobilská, Martina ; Kovář,, Pavel (referee) ; Nevřivová, Lenka (advisor)
This thesis deals with the problem of no-cement corundum refractory castables. In the theoretical part, it focuses on NCC refractory and its use, production technology and input raw materials. The second part of the theoretical work deals with MgAl2O4 spinel. The practical part of the thesis then continues in the topic and focuses on cement-free refractory concrete and the influence of MgO content on their properties.
Production of refractory aggregate in blast furnaces
Zemánek, David ; Tvrdík,, Lukáš (referee) ; Nevřivová, Lenka (advisor)
Firing of refractory aggregate takes place in blast or rotary furnaces. Raw materials for firing are refractory clays, claystones and shales. Sorting and sieving is performed before firing, in which occurs to formation of the fine clay. This waste is not useful for firing in common way in blast furnaces. Possibility, how to solve this problem, seems to be briquetting of fine clays. This method of proccesing fine clays brings with it new possibilities in refractory aggregate production. By adding a suitable correction material, such as mullite powder, special refractory grog with required properties can be produced on customers wishes.

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