Effect Of Firing Temperature Research Articles

Bending strength of porcelains

Porcelains in the quartz–metahalloysite+kaolin–K-feldspar system with different quartz grain sizes were investigated to study the effect of firing temperature on the bending strength. The degree of vitrification of the fired bodies was determined measuring the bulk density, relative percentages of constituent minerals by XRD and their microstructures using SEM techniques. The maximum bending strength was obtained in the 10–20 μm particle size quartz containing porcelains at 1300 and 1350 °C interval. The distribution of closed pores, their geometric shapes and possible link with each other control the bending strength of the porcelain body. In addition, the presence of unmelted fine quartz grains in the porcelain body also increases the bending strength. It was found that the bending strength increases with both increasing bulk density of the porcelain bodies and the firing temperature, but upon further heating, after reaching the maximum level, the bending strength decreases due to bloating of isolated pores and the disappearance of quartz, which are also associated with a decrease in bulk density.

Effect of Firing Temperature, Quartz Grain Size and Content on Bending Strength and Microstructure of Sanitaryware Porcelain

Effect of Firing Temperature, Quartz Grain Size and Content on Bending Strength and Microstructure of Sanitaryware Porcelain

Firing Technique for Preparing a BaMgAl10 O 17 : Eu2 + Phosphor with Controlled Particle Shape and Size

The effects of firing temperature on the crystallinity and the luminescent properties of phosphor have been investigated over the temperature 1000–1800°C range under preparative conditions which do not use any flux such as . The effects of particle shape and size of the ingredient on the phosphor have also been studied under a preparative condition which has a firing temperature of 1700°C and does not use any flux. A single‐phase with sufficient luminescent properties can be obtained over a firing temperature range of 1600–1800°C through formation of the intermediate product . Furthermore, the particle shape and size of the ingredient determine the particle shape and size of . High‐temperature firing in the absence of any flux has provided for the preparation of a single‐phase with various particle shapes, such as spherical or platelike, and particle sizes ranging from 2 to 18 μm. © 1999 The Electrochemical Society. All rights reserved.

Cubic Zirconia from Zircon Sand by Firing with CaO/MgO Mixture.

Cubic Zirconia from Zircon Sand by Firing with CaO/MgO Mixture.

Effect of Firing Temperature on the Thermal Stability of Low‐Oxygen Silicon Carbide Fibers

Low‐oxygen SiC fibers which were fabricated by curing with electron‐beam irradiation and firing at 1273 and 1573 K (fiber‐A and fiber‐B) were exposed at 1673 to 1973 K. Significant differences in surface composition, crystallinity, specific resistivity, and tensile strength were found between fiber‐A and fiber‐B. On exposing the fibers to high temperatures, they both crystallized nearly completely into intermixed β‐SiC and free carbon, and consequently the resistivity decreased markedly. Deep voids were formed at the surface of fiber‐A as a result of rapid dehydrogenation at the earliest stage of high‐temperature exposure. On the other hand, fiber‐B, which decomposed mildly, had a dense pore‐free structure. The fiber strength was proportional to the reciprocal square root of SiC crystal size. At the same crystal size, the strength of fiber‐A was lower because of the surface flaws.

Synthesis of (Pb,La) (Zr,Ti)O3 films using a diol based sol–gel route

Morphotropic phase boundary compositions of lead zirconate titanate (PZT) modified with 2, 5 and 10 mol% lanthanum (PLZT) have been prepared using a diol based sol–gel route. Thin films of these PLZT compositions were fabricated on platinized silicon substrates by a spin coating technique. The effects of firing temperature and lanthanum modifications were investigated with regard to phase development, microstructure, and ferroelectric and dielectric characteristics. A strong 〈1 1 1〉 orientation developed as the amount of lanthanum doping increased. The results indicate that the values of remanent polarization, Pr, and dielectric constant, er, decrease, relative to unmodified PZT, for films modified with 2 and 5 mol% lanthanum. The 5 mol% La films for example had a Pr of 14 μC cm−2 and an er value of 700 compared to 31 μC cm−2 and 1480 for undoped PZT films. At these La concentrations there was also an improvement in the leakage current density by two orders of magnitude compared with unmodified PZT. The 10 mol% La sample did not exhibit any switchable polarization behaviour.

Characterized microstructure of porous Si 3N 4 compacts prepared using the pyrolysis of polysilazane

The present paper describes the feasibility of controlling pore sizes of porous-fired Si 3N 4 compacts prepared using the pyrolysis of polysilazane, for developing a Si 3N 4 membrane manufacturing technique. Attention has been paid to the microstructure of these compacts in order to identify the main parameter governing the evolution of polysilazane-to-ceramic direct conversion. A volumetric shrinkage, stemming from the pyrolysis of polysilazane and the following crystallization of pyrolyzed polysilazane, have been shown to be of prime interest in the control of pore-size determination. A porosity of ∼35% was achieved in the fabrication of compacts, the pore-size distribution of which was controlled in the range 1–1000 nm, with polysilazane additions of 80–200 vol%. Also demonstrated was the effect of firing temperature on pore-size distribution. The bending strength of the processed specimens was equivalent to that of Vycor glass, indicating the feasibility of an application in the preparation of microstructured membrane system.

Effect of firing temperature of aluminum hydroxide on the possibility of preparing ceramics with the use of cip and on the properties of corundum ceramics

It is established that structural corundum ceramics (bioceramics) can be fabricated from aluminum hydroxide powder. The effect of the firing temperature and the pressure on the physicomechanical properties of the sintered material is established.

The Effect of Firing Temperature on the Elemental Characterization of Pottery

Neutron-activation analysis (NAA) of clay test tiles fired to temperatures from 100 ° to 1100 °C shows that with the possible exception of bromine, no volatilization of 34 elements occurs. Thus, there is little reason to consider firing temperature a potential confounding factor in ceramic compositional studies.

Growth of Mullite Whiskers on Alumina Particle by Thermal Decomposition of Clay Minerals

Whisker formation on alumina particles was attempted through growth of a number of fine mullite whiskers by the thermal decomposition of clay for porcelain at 1400 to 1600°C. After firing, the excess silica phase was hydrothermally dissolved in 2N NaOH solution at 180°C. The effect of firing temperature, and compositions of alumina and clay on the formation of mullite whiskers on alumina particles was investigated. In case of 18.8mass% alumina and 81.2mass% calcined clay, the growth of whiskers enhanced by the decomposition of clay was promoted, and alumina particles were coated with a number of mullite whiskers 50 to 200μm in length and 1 to 3μm in diameter just like sea urchin. Furthermore, alumina particles reacted with the excess amorphous silica in the fired clay to form small pillarlike mullite crystals in an alumina particle. But growth of whiskers was inhibited with increasing amount of alumina.

Effect of Firing Temperature and Porosity on Thermal Conductivity and Diffusivity of Iron Ore Pellets.

The thermal diffusivity and conductivity of iron ore pellet were determined by measuring temperature at surface and centre of pellet during heating and applying heat balance. The effect of firing temperature of pellets and its porosity on thermal conductivity were determined. The mineralogical changes on firing were investigated. The results were analysed by applying model equation and on the basis of basic sintering parameters to determine effective thermal conductivity at zero porosity with radial heat transfer.

Effects of Firing Temperature on Photocatalytic and Photoelectrocatalytic Properties of TiO 2

This paper describes studies of the effect of firing temperature on the photocatalytic and photoelectrocatalytic degradation of formic acid (HCOOH) using ultraviolet (UV) illuminated TiO{sub 2} thin films. Other variables, such as the potential applied [versus saturated calomel electrode (SCE)] to the film and the number of layers of film applied to the support were examined to determine optimum conditions for degradation. The transformation of TiO{sub 2} from anatase to rutile in the thin films was significantly retarded by placing the films on SnO{sub 2}-covered glass. Results indicate that films fired at 500 C showed the best efficiency for pure photocatalytic degradation, while films fired at 600 C had the best efficiency for the photoelectrocatalytic degradation of HCOOH. The efficiency of these photoelectrocatalytic reactions increased with increasing potential until 2 V (versus SCE) was obtained. A film with one layer (0.27 {micro}m thickness) showed the maximum degradation of HCOOH for photoelectrocatalytic reactions at 2 V (versus SCE), as no further increase in the rate of degradation of HCOOH was obtained by using thicker films.

Defluoridation of drinking water with pottery: effect of firing temperature

Excessive fluoride (F) in drinking water should be removed, but simple, inexpensive methods of fluoride removal are not readily available. This study examines the F(-)-binding capacity of clay and clayware, especially the effect of the firing temperature on the F(-)-binding process. A series of pots were made from ordinary potter's clay and fired at 500-1000 degrees C. Likewise, small clay bricks were fired and then crushed and sieved. NaF solutions containing 10 mg/l F- (10 ppm F-) were prepared. Suitable aliquots of the solutions were poured into clay pots or exposed to powdered clayware. Samples were taken at storage periods of 30 min to 20 days and analyzed for F- by ion-selective electrodes. The rate and capacity of F(-)-binding in the clayware varied with the firing temperature. Clay fired at approximately 600 degrees C was most effective. Temperatures over 700 degrees C caused a decline in F(-)-binding, and pottery fired at 900 degrees C and above seemed unable to remove F- from water. Pots fired at 500 degrees C or less cracked in water. The findings indicate that clayware, fired at an optimal temperature, may be of practical value for partial defluoridation of drinking water.

Novel Technique for Zirconia‐Coated Mullite

A novel, low‐cost, screen‐printing route to obtain zirconiacoated mullite starting from zircon powder has been proposed. A zirconia thick film of ∼30‐μm thickness with a strong adherence to the mullite substrate has been obtained. The role of zircon impurities in the coating characteristics as well as the effect of firing temperature are discussed.

Effect of Firing Temperature on Bending Strength of Porcelains for Tableware

Porcelains for tableware in the quartz–feldspar (sericite)–kaolin system were investigated to study the effect of firing temperature on the bending strength. The maximum bending strength of a body was attained at about 75°C below the temperature of complete sintering; therefore, its apparent porosity and the total porosity were almost 0% and 8.0%, respectively. Control of the finely dispersed, round, and isolated pores in the body was found to be necessary to attain strengthening of the body despite its relatively large porosity, and at the same time it was important that a large amount of fine quartz particles remain undissolved. Furthermore, a dense layer, formed close to the surface, was observed to strengthen the body more than that expected from its relative density when the body was fired above 1200°C.

The photoelectrochemical properties of Nb-doped TiO 2 semiconducting ceramic membrane

Photoelectrochemical properties of TiO 2 membranes were investigated for samples which were prepared from several colloidal suspensions and supported on F-doped SnO 2-coated glass. The effects of firing temperature, membrane thickness and Nb-doping level on quantum efficiency were examined in the range of 400-700°C, 0.1–1.1 μm and 0–10 mol % respectively. The conductivity, surface area and crystallinity of these membranes was also investigated as a part of this study. The colloidal suspensions were formed by hydrolysis of a titanium tetra-isopropoxide and niobium pentachloride solution. The photocurrent was found to be a function of firing temperature and membrane thickness. For undoped membranes, optimum photocurrent occurred at a thickness of ~0.3 μm for 600°C and 700°C, and 0.5 μm for 500°C. By doping Nb into the TiO 2 membrane, the conductivity and photocurrent of the membrane could be affected, and an optimum value in photocurrent versus Nb-doping level was determined. The surface area and crystallinity of TiO 2 were also influenced by Nb-doping level. The difference in crystallinity between supported and unsupported membranes was investigated as well.

Dielectric relaxator behaviour of Sr0.8La0.2Ti0.8Co0.2O3

Abstract Sr1−x La x Ti1−x Co x O3 for x ≤ 0.4 exhibits dielectric relaxator behaviour. The effect of firing temperature and different electroding on the dielectric properties of the sample Sr0.8La0.2Ti0.8Co0.2O3 has been investigated. Higher firing temperatures have no effect on the microstructure and on the resulting dielectric properties. On electroding with silver paint containing a low melting glass, CuO and Bi2O3 and heat-treating at 900 K for 15 minutes, the dielectric constant increased and the dielectric loss decreased. The dielectric characteristics have been analysed using complex plane impedance analysis.

Effects of firing temperature on morphology and crystal structure of zirconiumbis(monohydrogen phosphate) and its alkali salts

In zirconiumbis(monohydrogen phosphate)monohydrate, the stability of water of crystallization and of the crystal form was strongly influenced by its crystal size. The water of crystallization of a smaller crystal was completely released on heating to 200° C while a part of this water was held at 300° C in a larger crystal with a diameter of several micrometres. While a smaller crystal was decomposed by heating to 900° C and cubic zirconium pyrophosphate was formed, for a larger crystal,α-layered zirconium pyrophosphate was formed instead of cubic zirconium pyrophosphate and a layered structure was held. For the Na2-, K2- and Rb2-forms, good layer structure was retained even by heating to 1000° C. For the Li2-form, the layer structure was decomposed on heating at or above 900° C. The thermal stability of the layered structure increased with increasing crystal size and ionic radii of the alkali cation.

Effects of firing temperature on the fate of naturally occurring organic matter in clays

Experiments were carried out to test the effects of firing temperature on the fate of naturally occurring organic matter in clay. These results have important applications for the radiocarbon dating of archaeological ceramics. De Atley (1980) originally discussed the effects of carbon derived from coal or other old organic material in clays. Our experiments yielded quantitative measurements of carbon remaining in the ceramic after firing. Two commercial clay compositions were examined; low organic and high organic. Elemental analysis shows that carbon remained in ceramics fired at temperatures of 800–1000°C well exceeding the maximum firing temperatures of most primitive techniques. Organic burn-out is also dependent on the initial percentage of organics in the clay. Similar results for firings in oxidizing and non-oxidizing atmospheres suggest that organic burn-out is not only a combustive process but also a pyrolytic one.

The effect of firing temperature on the lung retention and translocation of Pu following the inhalation of 238PuO2 and 239PuO2 by CBA/H mice.

Mice were exposed by inhalation to sized aerosols of 238PuO2 and 239PuO2 which had been fired at temperatures from 550-1250 degrees C and groups killed at times between 1 d and 2 y after exposure. Measurements were made of 238Pu and 239Pu in the lungs, lung-associated lymph nodes, liver and skeleton. With 239Pu, lung retention and translocation were independent of firing temperature. With 238Pu on the other hand, the retention in lung was greater initially than for 239Pu but, with the low-fired oxide, eventually fell below that of 239Pu. With high-fired oxides, the lung retention of 238Pu still exceeded that of 239Pu after 2 y. Translocation to liver and bone was invariably greater for 238Pu than for 239Pu and was also dependent on firing temperature. The practical implications of these findings are discussed.