Papers by Keyword: Firing Temperature

Abstract: The main aim of this research was to investigate the effect of the addition of coal fly ash as a secondary waste material on the synthesis and properties of forsterite ceramics. The utilization of fly ash as a raw material, which contains flux oxides, reduce the necessary firing temperature for the synthesis of forsterite ceramics in comparison with forsterite ceramics synthetized from high purity or industrial materials, while preserving its refractory properties. The results revealed that forsterite was synthesized as a major crystalline phase in all samples. The optimal firing temperature for obtaining good physico-mechanical parameters was found to be between 1400-1600°C for high purity or industrial materials, while mixtures containing fly ash could achieve similar parameters at lower firing temperatures between 1200-1300°C. The decrease in refractoriness was found to be within acceptable limits for utilization as a refractory material. These findings demonstrate the potential for cost reduction and energy savings through the use of secondary waste materials and reduced firing temperature in the synthesis of forsterite ceramics.

Abstract: The aim of this study is to investigate the effect of different firing temperature on thermal conductivity of ceramic tiles. The body formulation powders of ceramic tiles were made according to the formulation given by company and compacted at 18 MPa using pressing machine in order to obtain button shape specimen with 50 mm diameter. The button shape specimen was fired at different firing temperature which 1150°C, 1175°C, 1200°C and 1225°C. Then, the thermal conductivity of fired specimens was measured by using Hot-Disk Thermal Constant Analyzer. Thermal conductivity result shows that the ceramic tile body fired at 1150 °C producing the lowest thermal conductivity values (0.97 W/mK) in comparison with other specimens. This low thermal conductivity performance is due to the high porosity value in the specimen as a result of more trapped air and implies delaying the heat transfer either inward or outward from the ceramic tiles. Therefore, this study proved that by altering firing temperature, different thermal conductivity values of ceramic tiles were obtained.

Abstract: This paper covers the production of ceramic materials from the tailings of ferrous and nonferrous metallurgy without using convention natural materials. The research addresses the dependency of the polymetallic ore tailings, chromite ore tailings, and physico-mechanical properties of ceramic materials based on the clayey portion of zircon-ilmenite ore gravity tailings. The dependency model is based on the actual experimental data and provides an analytical description of the test results as a function. Regression analysis has produced mathematical models for predicting the properties of ceramic mixtures at points not covered by the experiments. The paper presents five model equations to show:– how the content of chromite-ore tailings and polymetallic-ore tailings affects the compressive strength of ceramic bricks;– how the content of chromite-ore tailings and polymetallic-ore tailings affects the bending strength of ceramic bricks;– how the content of chromite-ore tailings and polymetallic-ore tailings affects the frost resistance of ceramic bricks;– how the content of chromite-ore tailings and polymetallic-ore tailings affects the thermal conductivity of ceramic bricks;– how the content of chromite-ore tailings and polymetallic-ore tailings affects the heat resistance of ceramic bricks;The research team has managed to produce ceramic bricks of high physico-mechanical properties from the tailings of ferrous and nonferrous metallurgy without using convention natural materials.

Abstract: In this paper, effects of incorporation of dry grass on the properties of clay bricks were investigated. Clay bricks fabricated with 0, 2.5, 5 and 7.5 % (w/w) of dry grass were tested. The clay brick specimens were fired at 900, 1000 and 1100 °C to study for bulk density, apparent porosity water absorption and compressive strength of brick samples were investigated. Results revealed that the bulk density of clay bricks were reduced when dry grass dosages increased. Results also shown that the increasing in bulk density were obtained when the firing temperature increased. The compressive strength of clay bricks was decreased when dry grass dosages increased. The addition of 2.5 % (w/w) dry grass fired at 1100 °C showed the optimal condition which indicated 11.6 MPa of compressive strength and 1.78 g/cm³ of bulk density. However, results indicated that a decrease in water absorption and apparent porosity were found when the firing temperature increased. Test results also revealed that the addition of dry grass for clay brick production lead to utilize a potential material as the additive to raw clay-bricks in the manufacturing of lightweight clay bricks.

Abstract: The fire performance of a geocement-based binder was investigated with a combination of analytical techniques, in terms of changes in composition and microstructure. Geocement, formulated as Na₂O∙Al₂O₃∙6SiO₂∙20H₂O, was prepared using metakaolin, sodium water-glass, rotten stone and sodium hydroxide. The mixture was homogenized by passing through a hydrodynamic cavitator. Cubes of 20 mm were prepared, hardened at laboratory conditions for 28 days, and subsequently burnt at 600, 800 and 1200 °C in a laboratory furnace. Cavitation treatment resulted in a highly amorphous binder; amorphous fraction decreased upon firing up to 800 °C due to crystallization, and increased above 1000 °C because of melt formation. Porosity increased with firing temperature and pores larger than 1 mm in diameter prevailed at 1200 °C. The material remained stable up to 1200 °C. The results indicate the adequacy of this geocement-based binder for preparing fire-protecting materials.

Abstract: Porcelain balls as grinding media are produced by firing process of clay, quartz and feldspar mixtures. This application need high technological properties such as high compressive strength and hardness, wear resistance, low water absorption and excellent chemical resistance. These properties are associated with higher firing temperatures. The porcelain balls were prepared by mixing 30 wt.% clay, 40 wt.% feldspar and 30 wt.% quartz. The samples were sintered at 1200°C, 1230°C, 1250°C, 1270°C and 1300°C for 2 hours with heating rate of 3°C/min. Both green powder and fired samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM).The properties of the fired samples were evaluated by compressive strength, hardness, shrinkage, water absorption, bulk density, and porosity measurement. Increasing of compressive strength, hardness and density are associated with increasing of firing temperatures. Porcelain balls PB1 and PB2 can be produced as grinding media with optimum mechanical and physical properties at firing temperature 1270°C and 1250°C, respectively.

Abstract: The aim of this work was to determine the properties of vitreous ceramic sanitary ware bodies according to the production of Khon Kaen ceramic sanitary ware industry, Thailand. Pottery stone was used as a replacing material in the commercial ceramic sanitary ware body formulation. The cast slurry of seven formulations was prepared by wet milling. The rheological properties (density and torsion viscosity) were investigated before slip casting. The test pieces were fired at 1175, 1200 and 1225^๐C and the physical-mechanical properties (firing shrinkage, flexural strength, and water absorption) were compared. As a result, pottery stone shows a possibility to replace quartz in the production. It could enhance all of the good properties at lower firing temperature. Using of pottery stone could reduce production cost in term of energy fuel by 4.45% when compared with commercial formulation.

Abstract: For ceramic industry, efflorescence is undesirable and cannot be completely eliminated from the finished products. The efflorescence is caused by soluble salts in the raw material and mostly appears as white deposit at the product’s surface. In this research, the removal of sulfate in the raw materials was studied. In addition, the sulfate ions were immobilized by forming a water-insoluble compound. The sulfate ions in the raw materials and fired products were extracted by distilled water, and the concentration was determined by using a UV-visible spectroscopy following the ASTM C1580-09 standard. Three sources of the raw materials from Tambon Suan Phung, Ratchaburi, Tambon Mae Win and Mae Ta, Chiang Mai, were analyzed for sulfate concentrations. The clay from Tambon Suan Phung, Ratchaburi which had the highest sulfate concentration was selected for further study on the effect of inhibitor and firing temperature on efflorescence inhibition. To reduce solubility of the sulfate, three kinds of inhibitor, i.e. barium chloride, barium carbonate and barium hydroxide, were added into the raw material at various concentrations, i.e. 0.5, 1.0, 1.5 and 2.0 wt% and homogeneously mixed by ball milling followed by the addition of distilled water to prepare the clay slip. The clay products were mold casted to 1 x 1 x 3 inch³ in size. Then, they were fired at 800, 900 and 1000 °C. It has been revealed that the addition of barium carbonate at 2 wt%, which is the highest amount employed in this study, and firing temperature of 900 °C resulted in least sulfate leaching due to the formation of water-insoluble barium sulfate. To perform a field test, the fired samples with and without the addition of barium carbonate were immersed in water for 4 months. The efflorescence was observed on the sample without barium carbonate within the 1^st month. In contrast, with the addition of barium carbonate, no efflorescence was observed after testing for 4 months.

Abstract: Due to low water absorption, high bending strength and abrasion resistance, and excellent chemical and frost resistance, porcelain building ceramic tiles are the highest increase in production and sales over all other kind of building ceramic tiles materials. In this paper, porcelain building ceramic tiles was prepared by a fast firing process of rare earth tailings as the main raw material, low fused sand and Zhuji porcelain sand et al mixture. Effects of firing temperature and forming pressure on the sintering behavior and mechanical property of porcelain building ceramic tiles were studied. The sintering behavior of the fired samples was evaluated by linear shrinkage and water absorption. The fired samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and bending strength measurements. The sample is pressured at 15 MPa and sintered at 1180 °C and endowed with 0.04% of the water absorption and 51 MPa of the bending strength, due to denser microstructure. The obtained results would contribute to save natural resources and protect environment.

Abstract: In the paper is presented the study of the Fe₂O₃ powders granulation effect on the firing parameters for the BaCO₃+6Fe₂O₃ powder mixture. The Fe₂O₃ powders were milled in a ball mill in wet medium. The results indicated that the granulation of Fe₂O₃ powders decreased rapidly with the increase of milling time. The Fe₂O₃ milled powders were then mixed with unmilled barium carbonate powders in order to form barium hexaferrite. After mixing, the powders were analized by thermogravimetric point of view and then the obtained barium hexaferrite samples were investigated by XRD analysis. It was observed that the firing temperature of the hexaferrites decreases with 10 degrees when we introduce in the mixture Fe₂O₃ milled powders with a fine granulation.