Ceramic Mass Research Articles

Influence of montmorillonite clay on the physical and mechanical properties of the ceramic mass

The intensification of the growth of industrial production of building materials causes an urgent need for economical use of material and fuel and energy resources, especially in such an energy-and resource-intensive industry as the production of construction ceramics. To improve the physical and mechanical properties of building ceramics, to reduce energy consumption during drying, as well as to increase the strength indicators, pilot tests of the influence of bentonite clay w for obtaining face wall ceramics were carried out. The regularities of the structure and phase formation of the ceramic composition depending on the firing temperature have been established. Modification of the raw mixture with bentonite clay to assess the increase in strength by 20-30% with a general decrease in the firing temperature by 100-120 ° C.

Economy analysis of the implementation of extruded tiles fabrication in a ceramic industry containing ornamental rock waste

AbstractAs a result of the economic crisis faced in Brazil, industries in the red ceramic sector have economic problems. The objective of this work was to evaluate, technologically and economically, through analysis of economy, the implementation of the production of ceramic tiles, a material with higher added value than bricks and ceramic blocks, in a ceramic industry located in the state of Rio de Janeiro, Brazil. The ceramic tiles were produced containing the incorporation of ornamental rock waste (ORW). The state has a region that has a red ceramic pole, but produces only products with lower added value. For this, specimens were produced with four different ceramic masses burned at temperatures in the range of 800 to 1050°C. Three masses were produced with different clays from the region (ceramic mass 1, 2 and 3) and a ceramic mass 4 was evaluated containing the clay that presented the best results and with the inclusion of sand and ORW, aiming at the analysis of economy. It was found that the masses containing only clays showed satisfactory parameters of resistance, but showed deficiencies in water absorption. The fourth mass, however, presented acceptable values in all the evaluated properties and was chosen to carry out a full‐scale industrial test, which enabled the development of economic analysis and an economic analysis using the theory of real options. The results obtained in this last stage were also positive, providing an internal rate of return of 16.82%, above the minimum practiced rate of 15%, proving the efficiency of the economy applied to the manufacture of extruded tiles in the industries of the study region.

Impact of the addition of dolomite to cream‐firing clays on the technological and color properties of sintered ceramics

AbstractSintered ceramics, represented by ceramic tiles or clinker bricks, are widely used in the building materials industry due to their technological properties and visual qualities. The topic of color changing of ceramic materials from cream‐firing clays with the use of mineral additives has not been addressed to date. The aim of the paper was to investigate the effect of granulation of dolomite additives to ceramic masses based on cream‐firing Borkowice clay on the color and properties of fired ceramic materials. The paper proposes that grain size of mineral additive affects the color of sintered ceramics. In order to confirm this hypothesis, a number of experiments were performed, consisting of determination of the color and technological properties of ceramic materials. The conducted tests showed that the color and technological properties of sintered ceramics are influenced by the grain size of the additives used.

К ВОЗМОЖНОСТИ ТРЕХМЕРНОЙ ПЕЧАТИ СИЛИКАТНЫМИ МАССАМИ С ИСПОЛЬЗОВАНИЕМ КЕРАМИЧЕСКИХ И ГИДРАТАЦИОННЫХ СВЯЗУЮЩИХ

The 3D printing technologies have appeared for a long time and are successfully used in a number of industries. The activities of many leading companies in the creation of layouts, models and prototypes of units, assemblies, products are practically not carried out without the use of 3D printing. The following are batch production technologies with high productivity combined with low cost, comparable to traditional methods of manufacturing products. The production of various products from silicate masses in an additive manner is seriously constrained by a number of issues due to the specifics of the material itself. One of them - achieving high physical and mechanical characteristics is possible only after hydration (for cements) or heat treatment (ceramic masses) of the product. Significant influence is exerted by the method of manufacturing the product. The most convenient and least energy-consuming method (in comparison with the powder 3D printing methods using laser sintering) is layer-by-layer slip casting or plastic extrusion, however, there are some unresolved problems. This paper highlights the key problems of using the additive method of manufacturing structural products on ceramic and hydration bonds using plastic and rigid masses in combination with vibration effects.

Microwave hybrid fast sintering of red clay ceramics

AbstractThis work aimed to examine the performance of the hybrid sintering of clay ceramic in a microwave furnace, compared to the sintering process in a conventional furnace. The raw materials were subjected to X‐ray fluorescence, loss on ignition (LOI), X‐ray diffraction, particle size distribution, real specific mass, and thermogravimetric analyses. The red clay ceramic mass was prepared, extruded, pre‐sintered in a conventional furnace at 600°C/60 min, and sintered at temperatures between 700 °C and 1100 °C. The sintering conventional (resistive oven) was carried out for 60 min with a heating rate of 10°C/min. In the microwave furnace, the sintering times were 5, 10, and 15 min, with a heating rate of 50°C/min, with a sintering chamber coated with silicon carbide (susceptor). The sintered specimens were characterized according to linear shrinkage, water absorption, apparent porosity, apparent specific mass, X‐ray diffraction, Raman spectroscopy analysis, spectroscopy analysis in the ultraviolet and visible regions, microhardness, and scanning electron microscopy. The results showed that microwave sintering promoted an increase in the microhardness and apparent specific mass, and reduction in water absorption and apparent porosity values, due to greater densification in the microstructure. The best results occurred for specimens sintered at 1100°C.

ВЛИЯНИЕ ВАНАДИЙОКСИДНОЙ ДОБАВКИ НА ТЕРМИЧЕСКИЕ ПРЕВРАЩЕНИЯ КЕРАМИЧЕСКОЙ МАССЫ

A comparative study of thermal transformations of ceramic mass (CM) based on α-Al2O3 modified with vanadium oxide additives introduced into CM by wet mixing and by deposition on the surface of the CM particles using molecular layering nanotechnology was carried out. The structural and chemical transformations of the obtained compositions were characterized by differential thermal analysis under linear heating conditions at a rate of 10°С/min, in the temperature range from room temperature to 1000°C. Changes in the phase composition, specific surface area of the compositions, and the state of the modifying additive before and after heating were studied using x-ray diffraction, low-temperature nitrogen adsorption, and ultraviolet–visible diffuse reflectance spectroscopy

Починка скола керамики при помощи прямой адгезивной техники самоадгезивной системой для фиксации на композитной основе Bifix SE (VOCO, Германия). Клинический случай

Summary. The single chips of ceramic structures remain a big problem for both the patient and for the doctor, especially in the frontal area, when for some objective reason, they cannot immediately change the construction. The work is justified by the choice of materials and the method of direct restoration of a single defect is described on a zirconium basis using the BIFIX SE self-adhesive system and the Futurabond U universal adhesive (VOCO, Germany). The repair of chipped ceramics is a real necessity. And the durability of restorations directly depends on the compliance with adhesive work technique, as well as the analysis of the reasons leading to the destruction of the ceramic mass and following up the patient's regime. Key words: the chipped ceramics, direct restoration, adhesive technique, self-adhesive system for fixing.

Research of the deformation of the shaping unit in an auger extruder caused by the extruding pressure in production of expanded clay

The technological process of forming expanded clay granules in an auger extruder is considered. Based on the analysis of well-known studies, considering the influence of conditions for shaping a ceramic mass on the quality of the produced porous aggregate, the following factor was identified: clogging of the shaping grid leads to an increase in pressure on it, its deformation and the impossibility of further operation. The authors note that there are practically no theoretical studies in the field of determining the most rational modes of functioning of the shaping equipment. The simulation model of an auger extruder shaping unit was developed in the Solid Works software environment, computational experiments on the influence of design parameters on shaping pressure were carried out, and recommendations for further technical application were formulated. The use of the results obtained will improve both the reliability of extruders with a perforated grid, as well as the quality of the final product with the specified quality parameters (bulk density and strength).

Selection of Compositions of Ceramic Masses on the Basis of Screenings Processing of Waste Materials for The Production Ceramic Using Mathematical Planning Methods

Selection of Compositions of Ceramic Masses on the Basis of Screenings Processing of Waste Materials for The Production Ceramic Using Mathematical Planning Methods

ВЛИЯНИЕ ДИСПЕРСНОСТИ ГЛИНОЗЕМА НА ТЕРМИЧЕСКИЕ ПРЕВРАЩЕНИЯ И СПЕКАНИЕ МНОГОКОМПОНЕНТНОЙ КЕРАМИЧЕСКОЙ МАССЫ

The effect of alumina wet mechanical grinding time on its fineness as well as subsequent solid-phase transformations and sintering of multicomponent ceramic mass based on it upon heating to 1000 °C was studied using x-ray diffraction, differential thermal analysis, nitrogen adsorption, granulometry and dilatometry.

A new eco-friendly mass formulation based on industrial mining residues for the manufacture of ceramic tiles

New eco-friendly mass formulations based on the scheelite and kaolin residues were developed to manufacture ceramic tiles. The start raw materials (scheelite residue, kaolin residue, feldspar and plastic clay) were characterized as to their chemical composition, main mineralogical phases, and particle size distribution. Three ceramic masses with 37 wt% of kaolin residues and different contents of the scheelite residues (2 wt%, 5 wt%, and 10 wt%) were formulated. The mass formulations were uniaxially pressed (19.6 MPa) to obtain samples with dimensions of 60 mm × 40 mm x 7 mm, which were dried at 110 °C/24 h, and sintered at different temperatures (1150 °C, 1200 °C, and 1250 °C). Dilatometric experiments measured thermal expansion coefficients. The results are in agreement with the literature, i.e., 6.0 μm/m°C−1, 6.1 μm/m°C−1 and 6.4 μm/m°C−1 to samples with 2 wt%, 5 wt%, and 10 wt% of scheelite residues, respectively. The potential of the mass formulations studied was evaluated by linear shrinkage, water absorption, apparent density, apparent porosity, flexural strength, and mineralogical phase identification. The results were compared with the literature experimental data and International Technical Standards. It was concluded that the samples investigated have suitable properties for use as ceramic and porcelain tiles. Also, the pseudowollastonite and mullite phases were identified in the sample with the lowest concentration of scheelite residue. These phases are responsible for increasing flexural strength.

Investigation of the sintering kinetic and development of ceramic masses for obtaining large-format porcelain stoneware in the conditions of high-speed firing

The paper considers the resource and energy saving reserves in the production of large-format stoneware slabs. The possibility of replacing high-quality feldspars with materials of technogenic origin, such as the extraction and processing waste of various feldspar-bearing rocks of domestic deposits has been investigated. The possibility of sintering process intensification has been investigated, as a condition for the use of high-speed firing modes in the stoneware production. As a result of the carried out studies, the kinetic features of ceramic masses sintering with alkaline syenites, granites and pegmatite enrichment wastes as fluxing component were determined. The formation conditions of densely sintered materials with a complex of high operational properties have been determined. The expediency of replacing Turkish feldspars with waste products of alkaline syenites has been established, while the level of physical, mechanical and operational properties of stoneware slabs meets the requirements of international standards. It is shown that, the use of complex flux, including feldspar-bearing rocks waste and dolomite, provides a significant decrease in the firing temperature of products (up to 1150 °C) while maintaining a high level of properties of stoneware slabs of class BІa. The obtained data indicate the possibility of optimizing the heat treatment parameters from the view point of energy saving with the further use of alternative fluxes in the large-format stoneware production. On the example of using the alkaline syenites wastes, the optimal ratios of the clay and fluxing components of ceramic masses have been established to obtain products with a complex of high performance characteristics when burning white clays of different chemical and mineral composition, which is a necessary condition for using a wide range of decorating techniques stoneware slabs. The structural-phase features of materials obtained under the conditions of high-speed firing are established: the formation of finely dispersed acicular mullite, which plays the role of a reinforcing component, as well as high structural homogeneity and maximum compaction, as evidenced by a few individual small pores presence. The combination of excellent technical qualities and large dimensions opens up new possibilities for the use of stoneware slabs as structural elements (countertops, ventilated facades, insulating panels for the installation of electrical systems, etc.).

Sol - gel method for producing of glass binding in the Li2O - Al2O3 - SiO2 system for ceramic materials

The results of glass binding obtaining in the Li2O — Al2O3 — SiO2 system for ceramic materials are presented in the article. The lithium aluminum silicate system was chosen taking into account the low temperature expansion coefficients of crystalline phases that form in it. This will allow controlling the thermal expansion of materials into which the glass binding will be introduced. A sol - gel method based on ethyl silicate and soluble salts of the corresponding oxides is proposed as a method for producing of glass binding. This method is more rational in comparison with the traditional method of glass melting due to low energy costs. Also, the method allows to obtain a more uniform and active product.
 The effect of glass binding on the properties of ceramic materials for various purposes has been investigated. As such materials, low-temperature electrotechnical porcelain, quartz ceramics, and engobe coatings were chosen. The glass binding was introduced into the raw material charge of these materials in an amount of 5 wt. %. Further, the properties of calcined product without additives and with additives under the same conditions were compared.
 The intense fluxing effect of glass binding during the formation of electrical porcelain has been established. The glass binding reinforces the effect of natural fluxes (pegmatites) that are present in the basic composition of the mass. This contributes to the material compaction during firing. The formation of eucryptite and spodumene helps to reduce the thermal expansion of material. The introduction of glass binding into the engobe led to a less intense compaction of its structure. This was observed due to an insufficient amount of the added glass binding for this type of material. In the composition of quartz ceramics, glass binding contributed to the material sintering, but the thermal properties were deteriorated.
 Thus, the sintering results of ceramic material with the introduction of glass binding in the charge composition are positive. However, sintering significantly depends on the material type. The glass binding stimulates the formation of a melt in which solid finely dispersed components of the ceramic mass dissolve. This contributes to the formation of a dense durable ceramic.

ВЛИЯНИЕ ГРУБОДИСПЕРСНЫХ КОМПОНЕНТОВ НА СВОЙСТВА КЕРАМИЧЕСКОГО МАТЕРИАЛА

In modern conditions, clay raw materials of fine-grained structure are used for the production of building ceramics. The task of using coarse non-traditional non-plastic components in the compositions of ceramic masses and the choice of rational sizes of their grains is relevant. The exclusion of pre-grinding determines the reduction of energy costs and, as a result, the cost of finished products. The paper offers an optiom of using diopside concentrate of various grain sizes in compositions with minor additions of clay and sodium silicate solution. The problems of stress development at the interface of grain and ligament contact, which in case of a negative outcome do not make it possible to obtain a strong structure of a ceramic shard, are solved. The presence of an insignificant voltage formed as a result of the relationship between the diopside and the forming glass phase is revealed, this does not prevent the consideration of the probability of obtaining a ceramic material. The study of the behavior of ceramic samples containing diopside of different granulometric composition when adding a solution of sodium-silicate glass after molding and firing shows the effectiveness of using diopside concentrate in 100-150 microns. Contacts of this size of diopside are wrapped in liquid glass during molding. A glass phase is formed when fired. In this case, the diopside is partially melted, but it is preserved and exists as an independent unit. A smaller grain size during sintering requires more glass phase, which leads to structural stresses, and with a larger size, not enough glass phase is formed and the strength of the material is significantly reduced. When studying the influence of grain size on the properties of the sample, the results of water absorption indicators of 7 %, mechanical compressive strength – 36 MPa, bending strength-17 MPa are obtained. It is found that the dispersion of diopside in 100–150 microns allows to develop a technology for the use of coarse-grained raw materials in the ceramic mass

НЕПЛАСТИЧНЫЕ СЫРЬЕВЫЕ МАТЕРИАЛЫ ДЛЯ ПРОИЗВОДСТВА СТРОИТЕЛЬНОЙ КЕРАМИКИ

research by some scientists shows that the most expensive element in the manufacture of construction ceramics are clay materials, in particular kaolins. They allow getting products with high strength, but at the same time increase significantly the mass refractoriness. In this connection, a significant amount of melt is added or the firing temperature is increased. Of course, this leads to an increase in the cost of products. In Russia, the reserves of these raw materials are insufficient and it is advisable to look for new non-traditional types of raw materials. There is a need to adjust the component composition of ceramic masses and use non-plastic raw materials. An example is natural wollastonites or their analogues in the form of diopside, which are a little-used type of mineral raw material. In the Siberian region, there are several deposits of non-plastic varieties of raw materials for the production of fired construction products. The most famous are the deposits of the Slyudyansky and Sayan districts. The authors present the results of analysis of diopside rocks, where the chemical, mineral compositions and behavior of samples under heating are studied. The absence of alkali and alkaline earth metal oxides in diopsides was determined. The content of iron oxide in the amount of 0.1% indicates the purity of the raw material. More than half of the composition is occupied by silica, which is 53% and 58% in the rocks of the Burutuysky and Sayan deposits, respectively. The basis of the mineral composition of the samples is diopside, with the presence of quartz, calcite, mica and magnesium carbonate. This range of minerals is traditional in many charges of ceramic materials. Therefore, the possibility of using diopside rocks in the production of building ceramic materials is quite high.

Исследование сушильных свойств керамической массы в системе «лёссовидный суглинок – зола Экибастузской ГРЭС»

The article investigates the drying properties of ceramic mass in the system “loesslike loam - ash of Ekibastuz HPP”. Ceramdor obtained from pure loam was selected as a control sample. A change in the structural and mechanical characteristics of ceramic masses during the drying process is associated with a change in temperature and moisture content of the material. The following results were obtained: molding moisture indicators, ductility numbers decrease with increasing ash. According to the classification of clay raw materials by plasticity, loam from a moderately plastic state goes into the category of low-plastic raw materials. With an increase in ash content of up to 20%, the sensitivity coefficient to drying leads to an increase in the time of crack appearance on the samples. A slight decrease in strength indicators is observed from 5.4 to 4.5 MPa. Thus, the results serve as the basis for the development of technological parameters in order to obtain ceramdor.

Addition of Ornamental Rock Residues on Ceramic Blocks: Physical and Chemical Analysis

The incorporation of industrial waste in cementitious materials is an alternative for its adequate disposal. Among the residues that do not yet have adequate disposal are the residues created by the ornamental rock industries. In this context, this work aims to identify and characterize clays of the region where the ornamental rock industry is dominant and to verify the performance of the ceramic masses with the incorporation of the marble and granite residue. Physical and chemical characterization tests were performed on both clay and residues. After the identification of the two best clays, ceramic masses were prepared where it was possible to evaluate the performance of the clays with each of the residues in incorporations up to 20 wt.%. The results indicated that CI-A with 15 wt.% marble incorporation obtained the best performance.

Mass Compositions Calculation on the Basis of Argillites at Ceramic Tiles Production

The results of selection and principles of calculating the ceramic masses composition for the clinker tiles’ production from argillites taking into account the raw materials’ characteristics are presented. The positive properties of argillites, as well as the properties that do not allow the tiles’ production of by stamping, which is traditional for these products’ manufacturing, are noted. Having low sensitivity to drying, low air shrinkage, high strength of the calcined shard, while being fusible sintering raw materials, argillites are low plastic and have insufficient bonding during molding, which indicates the need for corrective additives. In this work, the task to select the composition of ceramic masses to increase the plasticity of argillites while maintaining the positive properties of the main raw material was set. The authors proposed the use of siliceous clays as a corrective additive. An integrated approach was applied in calculating ceramic masses by grain composition and chemical and mineralogical indicators. Based on the research of A.I. Avgustinik, the oxide content Ca, Mg, Fe, Na, K and attitude Al2O3/SiO2 was taken into account. In order to obtain the densest packing, when calculating the grain composition, the natural dispersion of siliceous clays and the grain composition of previously prepared argillites were taken into account. The obtained theoretical calculations were tested in practice. Practical results showed that the 15% introduction of siliceous clay with the ceramic mass composition made it possible to obtain clinker tiles with improved physical and mechanical properties.

Coupled CFD and 1-D dynamic modeling for the analysis of industrial Regenerative Thermal Oxidizers

The emissions of volatile organic compounds (VOCs) produced in many chemical and manufacturing sectors are strictly regulated. Regenerative thermal oxidizers (RTOs), which employ ceramic masses for heat recovery in a cyclic operation mode, represent a promising technology enabling process intensification, by providing both high efficiencies of VOC removal and energy savings. This study advances a modeling framework which combines a 1-D transient model with 3-D CFD simulations to assist the design of 3-canister RTOs, focusing on the fluid dynamics, thermal and chemical behavior at different instants within the operational cycles. The analysis shows how different inlet-outlet-purge configurations affect the efficiency of VOC removal, which shows a minimum when the central canister is the outlet, as corroborated by experimental data and the analysis of the gas residence time. Some critical conditions of flow and temperature uniformity are investigated, showing that a random packing can be inserted underneath each monolithic block to ensure gas uniformity with only a limited increase in pressure drops. The approach and results reported point towards the establishment of robust criteria for RTO intensification.

КЕРАМИЧЕСКИЕ СТРОИТЕЛЬНЫЕ МАТЕРИАЛЫ С ИСПОЛЬЗОВАНИЕМ НЕТРАДИЦИОННОГО ВИДА СЫРЬЯ

the paper raises questions about the search for the possibility of obtaining a construction ceramic material using a special type of raw material component. Diopside concentrate was chosen as the basis for the ceram-ic masses due to its positive parameters necessary to improve the strength properties of the material and to support local deposits of raw materials in the East Siberian region. To reduce the optimal firing temperature, an aqueous-alkaline solution of sodium silicate was used in small quantities. The chemical composition of the diopside rock showed mainly the presence of silicon oxides. X-ray diffraction analysis revealed the presence of diopside, quartz and calcite. Sodium-silicate glass is characterized by a full content of silica and a modulus of 3. Using the state diagram of three-component systems, the temperature limits necessary for sintering ceramic masses are established. The fusibility curves show that at a temperature of 1040oC, the values of the primary melt for various compositions are 4-14%, and the total melt content is observed at 1475oC. The parameters of physical and mechanical properties of the ceramic material were determined, where at the firing temperature of 1000-1100oC the value of fire shrinkage was no more than 1%, water ab-sorption up to 10%, and compressive strength up to 31 MPa. Moreover, with an increase in the amount of diopside to 90% by weight, the strength increases, and shrinkage decreases. X-ray phase analysis of the compositions determined mainly analytical lines of diopside, which begin to decrease by 1000oC, which de-termines the relationship with the liquid glass. The DTA and TG curves of the thermogram showed endo-thermic and exothermic effects due to the release of adsorbed water and crystallization of glass. The possi-bility of obtaining high-strength low-shrink ceramics using diopside raw materials as the basis of ceramic masses when adding sodium-silicate glass in the form of a melt is established.