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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.
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The study of the refractory concrete binding system based on phosphoric acid and aluminous cement
Pavlík, Tomáš ; Švec, Jiří (referee) ; Šiler, Pavel (advisor)
This thesis deals with refractory concrete binding system based on aluminous cement and phosphoric acid. The prepared refractory concretes were fired at 1 000 °C. Various effects on compressive strength of refractory concrete were studied. The influence of aluminous cement content and phosphoric acid content, the influence of various admixtures, the influence of plasticizers and the influence of time and method of sample storage were studied. Simultaneous thermogravimetry and differential thermal analysis of the basic unfired sample were performed. Finally, selected refractory concretes were fired at 110, 200, 400, 600, 800, 900, 1 000 and 1 100 °C. The compressive strength of these samples was measured and powder X ray diffraction analysis was performed. The compressive strength of refractory concretes under intermediate temperatures (800–1 100 °C) was most increased in samples with metakaolin and gray microsilica.
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The Issue of Castable Corrosion.
Novobilská, Martina ; Kovář,, Pavel (referee) ; Nevřivová, Lenka (advisor)
This bachelor's thesis deals with the issue of corrosion of refractory concretes. The theoretical part focuses on the different types of corrosion and their occurrence and form in the various types of incinerators. Methodology of their testing is also described in this part. Refractory concrete resistance against corrosion is closely linked to its composition. Therefore, the practical part of this work focuses on the use of mixtures of aluminum oxides with a hydraulic binder, and subsequently their corrosion tests.
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Heat insulating moulded refractory concretes
Bednárek, Jan ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the possibility of specific weight lowering of kaolin suspensions using air-entraining agents. These agents are usually used as concrete admixtures. The goal of the thesis is to verify an alternative possibility of creating porous structure in kaolin suspensions in order to prepare heat insulating moulded refractory concretes without using lightweight fillers. The effect of several air-entraining agents was compared, after that the dosage of agent and mixing conditions were optimized. The stabilization of prepared foams and practical application of selected agents were also part of the thesis.
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Effect of acidic influence on the refractory castable with different cement content.
Mátl, Daniel ; Henek,, Milan (referee) ; Nevřivová, Lenka (advisor)
There are applications of refractory concretes for places where these are exposed to corrosive environments. This diploma thesis deals with both description the corrosive effects and methodology of their testing. One of the most important properties of materials, affecting the chemical corrosion resistance, is their density. The practical part of the thesis is focused on testing the refractory concretes which are currently used for applications. The aggregates were tested for the resistance to sulfuric acid.
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Assessment of resistance castables to chemically aggressive environments.
Mátl, Daniel ; Henek,, Milan (referee) ; Nevřivová, Lenka (advisor)
There are applications of refractory concretes for places where these are exposed to corrosive environments. This bachelor thesis deals with both description the corrosive effects and methodology of their testing. One of the most important properties of materials, affecting the chemical corrosion resistance, is their density. The practical part of the thesis is focused on testing the grogs which are currently used for production of refractory concrete. The aggregates were tested for the resistance to sulfuric acid.
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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.
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The study of the refractory concrete binding system based on phosphoric acid and aluminous cement
Pavlík, Tomáš ; Švec, Jiří (referee) ; Šiler, Pavel (advisor)
This thesis deals with refractory concrete binding system based on aluminous cement and phosphoric acid. The prepared refractory concretes were fired at 1 000 °C. Various effects on compressive strength of refractory concrete were studied. The influence of aluminous cement content and phosphoric acid content, the influence of various admixtures, the influence of plasticizers and the influence of time and method of sample storage were studied. Simultaneous thermogravimetry and differential thermal analysis of the basic unfired sample were performed. Finally, selected refractory concretes were fired at 110, 200, 400, 600, 800, 900, 1 000 and 1 100 °C. The compressive strength of these samples was measured and powder X ray diffraction analysis was performed. The compressive strength of refractory concretes under intermediate temperatures (800–1 100 °C) was most increased in samples with metakaolin and gray microsilica.
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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.
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The Issue of Castable Corrosion.
Novobilská, Martina ; Kovář,, Pavel (referee) ; Nevřivová, Lenka (advisor)
This bachelor's thesis deals with the issue of corrosion of refractory concretes. The theoretical part focuses on the different types of corrosion and their occurrence and form in the various types of incinerators. Methodology of their testing is also described in this part. Refractory concrete resistance against corrosion is closely linked to its composition. Therefore, the practical part of this work focuses on the use of mixtures of aluminum oxides with a hydraulic binder, and subsequently their corrosion tests.
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