Pyrophyllite as raw material for ceramic applications in the perspective of its pyro-chemical properties

Mukhopadhyay, Tapas Kumar; Ghatak, Sankar; Maiti, Himadri Sekhar

doi:10.1016/j.ceramint.2009.10.026

Cited by 54 publications

(36 citation statements)

References 22 publications

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“…Two peaks became obvious at 1429 and 1515 cm −1 in the IR spectra of F3 batch, which may be due to the increase of the bending vibration of O–H bond. While the peaks observed at about 1628 and 3427 cm −1 may be due to the vibration of O–H bond and to the O–H stretching of the surface water, respectively …”

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confidence: 99%

Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic

Zhang

Lei

et al. 2014

Int J Applied Ceramic Tech

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Four sets of Li 2 O-ZnO-Al 2 O 3 -SiO 2 (LZAS) glass-ceramics containing different content of fluorine were fabricated. With CaF 2 content increasing, the glass transition temperature (T g ) and crystallization temperature (T c1 , or T c2 ) decreased as differential scanning calorimetry results showed; this phenomenon could be explained based on the Fourier-transformed infrared spectra analysis. X-ray diffraction (XRD) results indicated that CaF 2 did influence the crystallization temperatures of some crystal phase in the LZAS glass-ceramics, the transformations from glass to b-quartz ss solid solution and b-quartz ss to b-spodumene occurred at lower temperatures, and the decrease could reach to 80°C. According to the scanning electron microscope analysis, the addition of F À ions can contribute to a microstructure with higher crystallinity and finer grain size. The density and average thermal coefficients of the studied glass-ceramics were influenced by the content of F À ions. All the results showed that CaF 2 did promote initial crystallization of LZAS glass and can be used as an effective nucleating agent in the LZAS system. *

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Section: Resultsmentioning

confidence: 99%

Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic

Zhang

Lei

et al. 2014

Int J Applied Ceramic Tech

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“…A better knowledge of thermal treatment of this clay can be useful in engineering the physical and chemical properties of the calcined clay for industrial applications. 5,6 Dehydroxylation process of other clays has been studied in detail but only limited reports exist for dehydroxylation of pyrophyllite. 3,4,[7][8][9][10] To the best of our knowledge no study has been done to evaluate pyrophyllite dehydroxylation in terms of kinetic modelling (mechanistic pathway).…”

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confidence: 99%

Non-Isothermal Kinetic Evaluation of Pyrophyllite Dehydroxylation

Shamim

Molla

Mukhopadhyay

et al. 2014

Transactions of the Indian Ceramic Society

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Dehydroxylation of clay minerals is an important process with several applications. Despite the industrial use of several well defined clay minerals, only the dehydroxylation kinetics of kaolinite has been reported. Still, the kinetics of these solid state reactions is yet to be understood using unambiguous model. In the present work, we have performed detailed kinetic analysis of dehydroxylation of pyrophyllite clay using non-isothermal kinetics by thermogravimetry (TG) at different heating rates. The TG data has been analysed initially with model-free methods (ASTM E 698, ASTM 1641, Friedman analysis and Ozawa-Flynn-Wall method). Interestingly, both the model-free methods of analysis have unequivocally indicated that activation energy (E act ) changes very marginally with progress of reaction and a single activation energy barrier is present. This surmises that the dehydroxylation process is a single stage process. A multivariate non-linear regression on the dynamic thermal data at different heating rates has been performed to determine the most probable kinetic model based on statistical fit. It has been found that, TG data provides best fit with regression coefficient (r 2 ) value of 0.994, when a single stage Avrami type diffusion reaction model is assumed, and an activation energy of 159 kJ.mol -1 .

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“…It is attributed to Si-O-Al bands. That change is related to the distortion of the silicate framework and it is specific for certain minerals [3]. In addition, four new absorption bands appeared at 865.…”

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“…Furthermore, the peak at 801.36 and 841.87 cm -1 result from the vibration of Al-O and Si-O out of surface [4,6]. The peak at 781.11 cm -1 is the Si-O stretching peak [3]. The peak at 542.55 cm…”

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“…For the sample P, the peak at 1121.49 cm -1 is an Al-OH stretching vibration [3] and the peak at 1071.43 cm -1 is the Si-O stretching vibration peak [4]. The peak at 1054.98 cm -1 corresponds to the intense Si O and Si O Al stretching frequencies, characteristic of aluminosilicates [3] and the peak at 952.72 cm -1 is the peak of Al-OH or Si-OH [3,5]. Furthermore, the peak at 801.36 and 841.87 cm -1 result from the vibration of Al-O and Si-O out of surface [4,6].…”

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Characterization of Heat Activated Minerals from Puturge (Malatya, Turkey)

Izci¹

2013

Microsc Microanal

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The samples were obtained from CimSa Mining Company operating industrial mineral deposits in Puturge-Malatya, Turkey. They were crushed, ground, and sieved to pass through a samples were heated at 400, 600, and 950 0 C for 3 h in air and then cooled to room temperature. Both the heating rates were 5.3 0 C/ min. Then they labeled as P400, P600, and P950.ion was employed for XRD measurements. Infrared spectra of the unheated sample (P sample) and the heated samples (P400, P600, and P950) were recorded (1400-400 cm -1 ) with Bruker Optics IFS66v/s FT-IR spectrometer at a resolution of 2 cm -1 at room temperature. 2628 show paragonite that is a type of mica such as muscovite. In the track of XRD of sample P950, new phases that cannot be seen in the sample P occurred. One of these phases is illite. The reason why kaolinite phase in the P sample is not seen in this P950 phase is that metakaolinite phase occurs [1]. Also, muscovite is a member of mica mineral group and its phase changes start when heat processes at 800-1000 0 C are applied [2]. The reason why potassium mica phase is seen in the track of XRD of the sample P950 may be this crystal structure change.FT-IR spectrum of P, P400, and P600 samples is shown in the Figure 2. For the sample P, the peak at 1121.49 cm -1 is an Al-OH stretching vibration [3] and the peak at 1071.43 cm -1 is the Si-O stretching vibration peak [4]. The peak at 1054.98 cm -1 corresponds to the intense Si O and Si O Al stretching frequencies, characteristic of aluminosilicates [3] and the peak at 952.72 cm -1 is the peak of Al-OH or Si-OH [3,5]. Furthermore, the peak at 801.36 and 841.87 cm -1 result from the vibration of Al-O and Si-O out of surface [4,6]. The peak at 781.11 cm -1 is the Si-O stretching peak [3]. The peak at 542.55 cmresults from the bending vibrations of Al-OH. The band at 696.25 cm 1 is due to the deformation and bending modes of the Si O bond. Since there is no new formation, P400 and the sample P have the same phases and peaks. However, in the P400 sample, with the temperature increase for the heat application, water peaks start to move away from the structure [7] and the intensity of the Al-OH peak at 1121.49 cm -1 decrease. It is not seen in the P600. At sample P600, there is also a change in the absorption band at 541.95 cm -1 . It is attributed to Si-O-Al bands. That change is related to the distortion of the silicate framework and it is specific for certain minerals [3]. In addition, four new absorption bands appeared at 865. 01, 735.79, 654.79, 567.71 and 437.81 cm -1 at 600 0 C. These peaks are the small peaks. When heated at 950 0 C, the intensities of the 735. 79, 695.54, 654.78, 486.02, 437.81, 422.38

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Pyrophyllite as raw material for ceramic applications in the perspective of its pyro-chemical properties

Cited by 54 publications

References 22 publications

Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic

Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic

Non-Isothermal Kinetic Evaluation of Pyrophyllite Dehydroxylation

Characterization of Heat Activated Minerals from Puturge (Malatya, Turkey)

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Pyrophyllite as raw material for ceramic applications in the perspective of its pyro-chemical properties

Cited by 54 publications

References 22 publications

Effect of CaF2 Addition on the Crystallization and Phase Formation in Li2O–ZnO–Al2O3–SiO2 Glass–Ceramic

Effect of CaF2 Addition on the Crystallization and Phase Formation in Li2O–ZnO–Al2O3–SiO2 Glass–Ceramic

Non-Isothermal Kinetic Evaluation of Pyrophyllite Dehydroxylation

Characterization of Heat Activated Minerals from Puturge (Malatya, Turkey)

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Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic

Effect of CaF₂ Addition on the Crystallization and Phase Formation in Li₂O–ZnO–Al₂O₃–SiO₂ Glass–Ceramic