Date: October 5, 2017
The paper deals with various influences that cause the effect of a sticking the ceramic to the metal bar after cooling the gating system. Adherence is undesirable from the point of view of users, as it make harder to clean the steel remains after casting, and the mechanically cleaned surface of steel remains are uneven. These fact attract attention of users who are afraid about peeling and abrading ceramics into castings. This phenomenon takes place at the ceramic - metal interface and is affected by properties of the metal and casting ceramics too. There are mentioned and discused the effects of certain properties of steels and irons such as melting point, viscosity, wettability, ferrostatic pressure, and ceramic properties such as refractoriness, chemical composition, additives and porosity. The porosity of several types of ceramic for gating systems was also studied in terms of pore size and pore distribution. The paper is complemented by the experience of adhering ceramics in metallurgical plants.
Non-shaped refractory materials are traditional part of assortment of the company P-D refractories CZ a.s. The average annual production is 3 000 to 4 000 tons. They can be divided into mortars, mastics and refractory dry mixes in general. The paper describes development of new brands of materials based on silica oxide. These materials are used for several purposes. The first group are mortars for silica bricks in coke batteries. The mortars have been modified to increase flexural strength during heating. The second group are refractory mastics which are also resistant to acid. These mastics are used to bond chimney pipes or for repairing industrial chimneys.
Usage of the ceramic filters in metallurgy and foundry has brought rise of interest in mechanism of their impact on solid impurities capture. This paper deals with the types of effects that play the main rules in melted aluminium refining process. How it seems, ceramic filters not are only physical barrier, but quality of filter’s material is very important to. Chemical character of the ceramic body gives next functionality what is mean - chemical reactivity toward solid impurities.
Use of SiC ceramics resistant against oxidation at higher temperatures (>1000 °C) is generally very expensive. This makes it hard to use them more broadly in various heat plants.
Průmyslová keramika, Ltd. has developed new line of refractory castables with different amount of SiC that express heightened oxidation resistance and presents alternative for standard SiC ceramics. Those castables are designed exclusively for production of fire preformed shapes.
The topic of this lecture is an introduction of this new line of refractory castables and comparison with similar commonly known materials. We also present different possibilities of its use and examples of existing applications.
The aim of this paper is to provide an overview of new refractory products, developed in SEEIF Ceramic, a.s. These are accessories for gating systems in foundries such as a new line of ceramic whirl gates or break-off slit gates, developed in cooperation with Slévárny Třinec, a.s. The use of these new products significantly improves the quality of the cast. The article describes their function and shows specific implementations.
Mullitized raw materials - grogs are used in many fields of industry due to their specific properties and relatively favorable price, therefore they find wide application. In this group are included raw materials with the content of alumina between 45 % and 70 % and they represent the so-called transition between fireclay and mullite grogs. Mullitized grogs are most often made of kaolins or clays enriched with higher alumina raw materials. Also, they can be calcined raw materials from the group of sillimanites.
The target of the development program in the P-D Refractories CZ company is to find out the conditions for the production of mullitized grogs, preferably from available domestic local raw materials, especially from kaolins and claystones. The output of this research is to obtain evidence for the modernization of shaft kilns in which fire clay grogs of the quality A111 and B253 are produced today.
This paper deals with suitable domestic raw materials (in binary system Al2O3 - SiO2) for their production, properties of mullitized grogs available on the market and the influence of melting oxides depending on their usage, i.e. the application temperature of these refractory materials.
Date: October 6, 2017
Ceramics based on ZrO2 belongs to a group of special refractory ceramics. ZrO2 has excellent properties, high quality and refractoriness. Methods of shaping this type of ceramic may be variable with respect to the resulting product type and its subsequent use. This contribution is part of the research development and improvement of the quality of isostatically pressed crucibles based on ZrO2. ZrO2 is present in three modifications. Changing the modification is accompanied by volume change in material. Material based on ZrO2 is produced by of company Capital Refractories s.r.o., Czech Republic. This material is using for isostatic press crucibles for special application. The identification of modification transformation in system ZrO2 is a precondition for efficient for production of crucibles. The aim of our work is to reduce formation cracks on the surface for efficient of crucible production.
A development of RMS a.s. Košice is focused on improvement of the refractoriness under load and reduction of thermal conductivity of the lightweight aluminosilicate bricks and castables and effective use of energy sources in the thermal aggregates. Current trends in a thermal aggregate design are aimed to the effective utilization of resources so it is necessary to look for the raw materials, working under severe conditions and at relatively high temperatures. A purpose of the present lecture is presentation of portfolio of the innovated insulation products made by RMS, a.s. Košice that includes several types of the lightweight castables and bricks, and comparison of the thermal-mechanical and thermal-physical properties of original and innovated products on the basis of the advanced lightweight aluminosilicate materials.