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Journal ArticleDOI

Kinetics of thermal expansion of illite-based ceramics in the dehydroxylation region during heating

01 Jan 2017-Journal of Thermal Analysis and Calorimetry (Springer Netherlands)-Vol. 127, Iss: 1, pp 291-298
TL;DR: In this article, the authors investigated the kinetics of the illite dehydroxylation using data from non-isothermal thermodilatometric experiments, and their results were discussed.
Abstract: The kinetics of the illite dehydroxylation is investigated using data from non-isothermal thermodilatometric experiments. An illitic clay with more than 70 % of illite was thermally treated under several heating rates from 1 to 15 °C min−1 in the dehydroxylation region. Model-free and nonlinear model-fitting methods were used to analyze the data, and their results are discussed. The dehydroxylation of the trans-vacant and cis-vacant illite layers can be described by the Avrami–Erofeev model with the exponent values 1.010 and 2.1, respectively, and the apparent activation energies of 119 and 184 kJ mol−1, respectively. The obtained kinetic parameters were used for the calculation of an optimal heating regime in order to achieve a constant thermal expansion rate in the dehydroxylation region for an illite-based ceramic body.
Citations
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Journal ArticleDOI
TL;DR: In this article, a tutorial paper on uncoated ceramics is presented, focusing on the operational phases required prior to firing (drying, piling, fuel supply) and the transformations that occur in the clayey paste during firing.
Abstract: Focused on uncoated ceramics, this tutorial paper is divided into two main sections. The first section deals with the operational phases required prior to firing (drying, piling, fuel supply). Then, the second chapter deals with the transformations that occur in the clayey paste during firing. An overall understanding of the firing process includes several issues to be considered and properly investigated. Thereafter, the thermal behaviour of several mineralogical phases (calcite and dolomite; quartz and cristobalite; K-feldspar and plagioclase; rutile and anatase; haematite, maghemite, hercynite and metallic Fe; illite, muscovite, biotite and chlorite; wollastonite, melilite, anorthite and monticellite; diopside and kaolinite) is described. Four brief chapters are further dedicated to the development of the amorphous/glassy component, to the matrix and its porosity, to the colour and the organic matter and to the variations in chemical composition, respectively. The concluding remarks provide a short list of the analytical techniques that have been commonly applied to the investigation of firing conditions and a concise summary of the state of the art of the “firing issue”. The method to be applied in future experimental reproductions and the opportunity itself to investigate the “firing issue” in various contexts are further discussed.

60 citations

Journal ArticleDOI
TL;DR: The thermal transformation of two shales containing illite-chlorite (I/Ch), feldspars and quartz from La Cabanita quarry (Olavarria, Argentine) was studied by TG-DTA, XRD and FTIR.

38 citations

Journal ArticleDOI
TL;DR: In this article, the thermal behavior of two mineral-type coal gangues under different temperature conditions was investigated by heating treatment of coal gangue and illite-types based on thermal analysis, X-ray diffraction (XRD), IR and scanning electron microscopy (SEM).
Abstract: The thermal behavior of two mineral-type coal gangues under different temperature conditions was investigated by heating treatment of kaolinite-type coal gangue and illite-type coal gangue based on thermal analysis, X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). Thermogravimetric, differential thermogravimetric and differential scanning calorimetry results show the thermal decomposition process of kaolinite-type coal gangue and illite-type coal gangue can be divided into three stages, thermal decomposition of kaolinite and illite clay minerals occurred in the first stage and the third stage, and thermal decomposition of carbon material in coal gangue samples occurred in the second stage. Compared with illite-type coal gangue, the volatile of kaolinite-type coal gangue is released more intensely and pyrolysis performance of kaolinite-type coal gangue was better; initial temperature of heat decomposition was lower. The XRD, IR and SEM results showed the mineral phase transformation of kaolinite-type coal gangue occurred at 500 °C, the microscopic kaolinite changed obviously and its flake and layered structure started to break, and the phase of kaolinite transformed into amorphous glassy state, which was metakaolinite. In contrast, the mineral phase transformation of illite-type coal gangue occurred at 900 °C. According to the results of various research methods, it is considered that the thermal stability of kaolinite-type coal gangue is lower than that of illite-type coal gangue. This study has some theoretical significance for the rational use of coal gangue to produce highly activity powder materials.

37 citations

Journal ArticleDOI
TL;DR: In this article, a review of the thermal transformation in clay minerals under firing and about the properties of fired clay are expressed quantitatively with the extent of conversion, α, which is the function of two parameters of firing process, time t and temperature T: α = f(t, T).
Abstract: The review consists of four parts. Part I is about the thermal transformation in clay minerals under firing and about the properties of fired clay. The transformations in the clay are expressed quantitatively with the extent of conversion, α, which is the function of two parameters of firing process, time t and temperature T: α = f(t, T). Part II is about the estimation of firing temperature after the analysis of the products of firing clays. All the estimations are speculative, without mathematical equations. It is impossible to derive the value of only one variable T from α = f(t,T), the function of two variables. Part III is about the long-term inverse transformation in fired ceramic paste under ambient conditions. The mass gain as a function of time is used for the evaluation of the time elapsed from the ancient firing, t. Part IV is about the visualization of the extent of conversion of the clay in the paste after all direct and reverse reactions, i.e., α.

16 citations


Cites methods from "Kinetics of thermal expansion of il..."

  • ...The kinetics of the illite dehydroxylation was investigated using data from nonisothermal thermodilatometric experiments with three clay pastes of different compositions at different heating rates [147]....

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Journal ArticleDOI
TL;DR: In this paper, electrical conductivity measurement was used to characterize thermophysical processes occurring in illitic clay during firing, and the AC conductivity was measured at 10 different frequencies, ranging from 500 Hz up to 2 MHz.

15 citations

References
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Journal ArticleDOI
TL;DR: In this article, the authors have developed recommendations for reliable evaluation of kinetic parameters (the activation energy, the preexponential factor, and the reaction model) from the data obtained by means of thermal analysis methods such as TGA, differential scanning calorimetry (DSC), and differential thermal analysis (DTA).

4,112 citations


"Kinetics of thermal expansion of il..." refers background or methods in this paper

  • ...The temperature dependence of the reaction rate is mostly expressed by the Arrhenius equation [24],...

    [...]

  • ...This is the basis of the well-known Friedman method [24, 28]....

    [...]

  • ...The reaction model f(a) is believed to reflect the actual physical background of the investigated process [24]....

    [...]

  • ...(2) has to be extended to a system of differential equations with one equation for each individual reaction step [24]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data, based on the inter-comparison of experiments which were performed at different linear rates of heating.
Abstract: A technique was devised for obtaining rate laws and kinetic parameters which describe the thermal degradation of plastics from TGA data. The method is based on the inter-comparison of experiments which were performed at different linear rates of heating. By this method it is possible to determine the activation energy of certain professes without knowing the form of the kinetic equation. This technique was applied to fiberglass-reinforced CTL 91-LD phenolic resin, where the rate law - (1/we)(dw/dt) = 1018e−55,000/RT [(w - wf)/w0,]5, nr.−1, was found to apply to a major part of the degradation. The equation was successfully tested by several techniques, including a comparison with constant temperature data that were available in the literature. The activation energy was thought to be correct within 10 kcal.

3,002 citations


"Kinetics of thermal expansion of il..." refers methods in this paper

  • ...This is the basis of the well-known Friedman method [24, 28]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors present a set of recommendations for obtaining kinetic data that are adequate to the actual kinetics of various processes, including thermal decomposition of inorganic solids; thermal and thermo-oxidative degradation of polymers and organics; reactions of solids with gases; polymerization and crosslinking; crystallization of polymer and inorganics; hazardous processes.

890 citations


"Kinetics of thermal expansion of il..." refers methods in this paper

  • ...To minimize thermal gradients within the sample during TD experiments, the original diameter *12 mm of the samples for TD measurements was reduced to *7 mm by using a lathe [21, 22]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the sources and calculation of thermal stresses are considered, together with the factors involved in thermal stress resistance factors, and properties affecting thermal stress resilience of ceramics are reviewed and testing methods are considered.
Abstract: The sources and calculation of thermal stresses are considered, together with the factors involved in thermal stress resistance factors. Properties affecting thermal stress resistance of ceramics are reviewed, and testing methods are considered.

658 citations


"Kinetics of thermal expansion of il..." refers background in this paper

  • ...Furthermore, depending on the size and shape of the ceramic body, the heating rate must be generally decreased to minimize the thermal gradients inside the body [31]....

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Journal ArticleDOI
TL;DR: The results of the ICTAC Kinetics Project have been discussed in this article, where the authors have applied various model-free techniques that employ multiple sets of isothermal or nonisothermal data obtained at different temperatures or/and at different heating rates.

495 citations