AMEUR Ouali

DJAAFER Hayat

Analytical Study of the Local Raw Materials Used in the Construction Bricks Industry

BAHACHE Messaouda

Etude et simulation des phénomènes diélectriques dans les matériaux ferroélectriques PZT de formule Pb( ZrxTi1-x )O3

DJEDID Fatiha

Elaboration et caractérisations diélectriques de matériaux ferroélectriques de type PZT

BENYATOU Samia

L’étude des méthodes de préparation de l’anorthite et le corderite à partir de kaolin de djebel Debagh type DD1

FERAHTIA Samia

L’étude de l’influence des oxydes de calcium et de magnésium sur le frittage de l’anorthite et le corderite à partir kaolin de djebel Debagh type DD3

The study develloprd tripropyleneglycol daicrylate / montmorillonite nano composites vi in-situ physical cross-linking of TPGDA with differenttypes of cationically exchanged motmorillonite.

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Ameur Ouali , , (2024-01-01), Enhancing Dielectric Properties through Nanocomposite Formation of Tripropylene Glycol Diacrylate and Montmorillonite, Tobacco Regulatory Science (TRS), Vol:9, Issue:-1, pages:3938-3955, TOBACCO REGULATORY SCIENCE GROUP

BSTRACT Using DTA/TG thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), crystallization kinetics of -cordierite ceramic from MgO–Al2O3–SiO2– TiO2 glasses obtained through melt cooling are presented. Under 40 cm3/min argon gas flow, DTA experiments were carried out on samples ranging from room temperature to 1400 °C. This study utilized heating rates of 10, 20, 30, 40, and 50 °C/min. The sintered powders' phase transformations were characterized by XRD. Using DTA results, the activation energy

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Ameur Ouali , ,(2023-10-28), Crystallization Kinetics Study of α-Cordierite from MgO– Al2O3–SiO2–TiO2,10th INTERNATIONAL CONFERENCE ON COMPUTATIONAL AND EXPERIMENTAL SCIENCE AND ENGINEERING (ICCESEN-2023),ANTALYA -TURKEY

Crystallization Kinetics Study of α-Cordierite from MgO– Al2O3–SiO2–TiO2 Ameur OUALI , Smail LAMARA, Foudil SAHNOUNE Physics and materials chemistry laboratory, Department of Physics, University of M’sila, 28000 M’sila, ALGERIA ABSTRACT Using DTA/TG thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), crystallization kinetics of -cordierite ceramic from MgO–Al2O3–SiO2– TiO2 glasses obtained through melt cooling are presented. Under 40 cm3/min argon gas flow, DTA experiments were carried out on samples ranging from room temperature to 1400 °C. This study utilized heating rates of 10, 20, 30, 40, and 50 °C/min. The sintered powders' phase transformations were characterized by XRD. Using DTA results, the activation energy values for cordierite formation were measured under both non-isothermal (Kissinger, Boswell, and Ozawa methods) and non-isothermal (Johnson–Mehl–Avrami (JMA) theory) treatments of 845 and 720 kJ mol-1, respectively. When non-isothermal treatments were used, the growth morphology parameters n (the Avrami parameter) were found to be close to 1.5, when isothermal treatments were used (the Ligero method), and Matusita et al. found that m (the numerical factor) was 1.5. The fact that the growth morphology parameters n and m are approximately 1.5 indicates a diffusion-controlled polyhedron-like three-dimensional growth from a constant number of nuclei. Keywords: Cordierite, Differential thermal analysis, Avrami parameter, Activation energy  Corresponding Author

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Ameur Ouali , Foudil SAHNOUNE , smail LAMARA , ,(2023-10-27), Crystallization Kinetics Study of α-Cordierite from MgO– Al2O3–SiO2–TiO2,10th INTERNATIONAL CONFERENCE ON COMPUTATIONAL AND EXPERIMENTAL SCIENCE AND ENGINEERING (ICCESEN-2023) 27-30 October 2023, ANTALYA-TURKEY,ANTALYA-TURKEY

Abstract In this work, Tripropylene Glycol Diacrylate (TPGDA)/Montmorillonitenanocomposites were elaborated via in-situ physical cross-linking of TPGDA method with different type of cationically exchanged montmorillonite (MMt-M+; M = K, Na, Li). In addition, the cationic exchange of the Montmorillonite clay is carried out using the chemical products KCl, NaCl and LiCl as source of the cations K+, Na+, Li+ respectively. The synthesized cross-linked (TPGDA/MMt-M+) nanocomposites were characterized by Fourier Transform Infrared Spectrum (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis (TGA).Based on the DTG curve, the activation energy and kinetics parameters of the decomposition phase were calculated for each sample using the Coats and Redfern model. Keywords: Nanocomposites, Montmorillonite, TPGDA.PotassiumPeroxydisulfate.

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Ameur Ouali , , (2023-07-01), Elaboration and characterization of cross-linked (Tripropylene glycol diacrylate)/modified Montmorillonite-M+ nanocomposites, NeuroQuantology, Vol:26, Issue:7, pages:1404-1415, Publisher country is Turkey.

Abstract:Using DTA/TG thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), crystallization kinetics of -cordierite ceramic from MgO–Al2O3–SiO2–TiO2 glasses obtained through melt coolingare presented. Under 40 cm3/min argon gas flow DTA experiments were carried out on samples at temperatures ranging from room temperature to 1400 °C. This study utilized heating rates of 10, 20, 30, 40, and 50 °C/min.The sintered powders' phase transformations were characterized by XRD.Using DTA results, the activation energy values for cordierite formation were measured under both non-isothermal (Kissinger, Boswell, and Ozawa methods) and non-isothermal (Johnson–Mehl–Avrami (JMA) theory) treatments of 845 and 720 kJ mol-1, respectively.When non-isothermal treatments were used, the growth morphology parameters n (the Avrami parameter) were found to be close to 1.5, when isothermal treatments were used (the Ligero method), and Matusita et al. found that m (the numerical factor) was 1.5.The fact that the growth morphology parameters n and m are both approximately 1.5 indicates a diffusion-controlled polyhedron-like three-dimensional growth from a constant number of nuclei. Keywords:Cordierite, Differential thermal analysis, Avrami parameter, Activation energy

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Ameur Ouali , OUALI Ameur, ,(2022), Non-isothermal kinetics crystallization study of α-cordierite from MgO–Al2O3–SiO2–TiO2,International Conference on Mechanics and Energy December 21-23, 2022, Hammamet, TUNISIAICME'2022,Hammamet, TUNISIAICME'2022

Magnesium and these alloys are very active metals that owe its resistance to corrosion by the formation of a protective layer. Given the importance of its applications, it is necessary to protect it against corrosion. To prevent this phenomenon, several techniques can be used namely the addition of corrosion inhibitors, and surface treatments. To study the physico-chemical properties of AZ91 magnesium alloy ( Mg -9 wt% Al- 1 wt% Zn ), The measurements were performed using the techniques of X-ray diffraction (In-situ) ,differential scanning calorimetric analysis (DSC) and microhardness measurements and dilatometer method ,was used to determinate the dissolution of precipitation of second phase β ( Mg17Al12 )at 420°C for different ageing times and a comparative study between dissolution of discontinuous continuous precipitates, the all samples were heated from room temperature observed at 150,250,350°C respectively, at heating rates of 10–30 °C/min.

Citation

Ameur Ouali , ,(2019), Kinetic parameters of γ–Mg17Al12 phase dissolution from AZ91 alloy,International Conference on Materials Science ICMS2018,Antalya (Turkey)

The clay is one of the most used natural materials in the ceramic industry with very different applications such as pottery, tiles, cement and brick. The latter is used as building materials because of their excellent thermal and mechanical properties. In the present study, the mechanism and kinetic parameters of transformation Phases of Algerian clay from Al-maathed was studied by Differential Thermal Analysis (DTA) and dilatometry analysis (DL) technique. Phases present and their transformations, the activation energy, and the sintering mechanism were evaluated through x-ray diffraction, differential thermal analysis (DTA), thermogravimetric (TG) and dilatometer. The activation energy calculated by non-isothermal (Kissinger method) treatments, for the Phases transformation are 1000 kJ/mol and for the sintering is 460 KJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic and is related to Tm and the m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method were both about 1,2 sintering clay. These values indicating that bulk nucleation is dominant in sintering clay by three-dimensional with polyhedron-like morphology controlled by interface reaction. Keywords: Ceramics, Thermal analysis, Powders. Clay.

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Ameur Ouali , Foudil SAHNOUNE , MENAD Heraiz , ,(2019), Kinetic Parameters and sintering Mechanism of Algeria Clay Powder Using Differential Thermal Analysis (DTA) and Dilatometry (Dl),International Conference on Technology, Engineering and Science (IConTES),Antalya (Turkey)

International Conference on Technology, Engineering and Science (IConTES) October 26-29, 2019 – Antalya/TURKEY Abstract Book 13 KINETIC PARAMETERS AND SINTERING MECHANISM OF ALGERIA CLAY POWDER USING DIFFERENTIAL THERMALANALYSIS AND DILATOMETRY Ouali Ameur * University of M'sila, Algeria Sahnoune Foudil University of M'sila, Algeria Heraiz Menad University of M'sila, Algeria The clay is one of the most used natural materials in the ceramic industry with very different applications such as pottery, tiles, cement and brick. The latter is used as building materials because of their excellent thermal and mechanical properties. In the present study, the mechanism and kinetic parameters of transformation Phases of Algerian clay from Al-maathed was studied by Differential Thermal Analysis (DTA) and dilatometry analysis (DL) technique. Phases present and their transformations, the activation energy, and the sintering mechanism were evaluated through x-ray diffraction, differential thermal analysis (DTA), thermogravimetric (TG) and dilatometer. The activation energy calculated by non-isothermal (Kissinger method) treatments, for the Phases transformation are 1000 kJ/mol and for the sintering is 460 KJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic and is related to Tm and the m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method were both about 1,2 sintering clay. These values indicating that bulk nucleation is dominant in sintering clay by three-dimensional with polyhedron-like morphology controlled by interface reaction. Keywords: ceramics, thermal analysis, powders, clay

Citation

Ameur Ouali , Foudil SAHNOUNE , MENAD Heraiz , ,(2019), Kinetic Parameters and sintering Mechanism of Algeria Clay Powder Using Differential Thermal Analysis (DTA) and Dilatometry (Dl),International Conference on Technology, Engineering and Science (IConTES) Antalya, Turkey,Antalya, Turkey

International Conference on Technology, Engineering and Science (IConTES) October 26-29, 2019 – Antalya/TURKEY Abstract Book 13 KINETIC PARAMETERS AND SINTERING MECHANISM OF ALGERIA CLAY POWDER USING DIFFERENTIAL THERMALANALYSIS AND DILATOMETRY Ouali Ameur * University of M'sila, Algeria Sahnoune Foudil University of M'sila, Algeria Heraiz Menad University of M'sila, Algeria The clay is one of the most used natural materials in the ceramic industry with very different applications such as pottery, tiles, cement and brick. The latter is used as building materials because of their excellent thermal and mechanical properties. In the present study, the mechanism and kinetic parameters of transformation Phases of Algerian clay from Al-maathed was studied by Differential Thermal Analysis (DTA) and dilatometry analysis (DL) technique. Phases present and their transformations, the activation energy, and the sintering mechanism were evaluated through x-ray diffraction, differential thermal analysis (DTA), thermogravimetric (TG) and dilatometer. The activation energy calculated by non-isothermal (Kissinger method) treatments, for the Phases transformation are 1000 kJ/mol and for the sintering is 460 KJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic and is related to Tm and the m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method were both about 1,2 sintering clay. These values indicating that bulk nucleation is dominant in sintering clay by three-dimensional with polyhedron-like morphology controlled by interface reaction. Keywords: ceramics, thermal analysis, powders, clay

Citation

Ameur Ouali , Foudil SAHNOUNE , MENAD Heraiz , ,(2019), Kinetic Parameters and sintering Mechanism of Algeria Clay Powder Using Differential Thermal Analysis (DTA) and Dilatometry (Dl),International Conference on Technology, Engineering and Science (IConTES) Antalya, Turkey,Antalya, Turkey

This study investigated the effect of aging on the precipitation and kinetics of second-phase Mg17Al12 in AZ91 magnesium alloy (Mg-9 wt% Al-1 wt% Zn), using X-ray diffraction, microhardness measurements, and differential scanning calorimetric analysis (DSC). With the last instrument, the all samples were heated from room temperature to 400 °C, at heating rates of 10–30 °C/min. The results were supplemented by measuring the average of activation energies, using isothermal treatments by Johnson–Mehl–Avrami (JMA) methods and by non-isothermal treatments using Ozawa, Boswell, Kissinger, Mahadevan, Augis and Bennett methods, were around 67.18 and 62.02 kJ/mol. The frequency factor k0 calculated by the isothermal treatment is equal to 1.24 109 s−1. In non-isothermal treatment, the numerical factor m and the Avrami parameter n is estimated to be approximately equal to 3 and 2.79 respectively. This value corresponding that the bulk nucleation with a constant number of nuclei was dominant in three-dimensional (polyhedron) controlled by interface reaction

Citation

AMAR Djemli , Ameur Ouali , MohamedAmine GHEBOULI , Hocine BELHOUCHET , Fatmi messaoud, Tayab Chihi, , (2018-07-20), Heat treatment and kinetics of precipitation of β-Mg17Al12 phase in AZ91 alloy, Results in Physics, Vol:10, Issue:2018, pages:693-698, Elsevier

This study investigated the effect of aging on the precipitation and kinetics of second phase Mg17Al12 in AZ91 magnesium alloy (Mg-9 wt% Al-1 wt% Zn), using X-ray diffraction, microhardness measurements and differential scanning calorimetric analysis (DSC). With the last instrument, the all samples were heated from room temperature to 400 °C, at heating rates of 10-30 °C/min. The results were supplemented by measuring the average of activation energies, using isothermal treatments by Johnson-Mehl-Avrami (JMA) methods and by non-isothermal treatments using Ozawa, Boswell, Kissinger, Mahadevan, Augis and Bennett methods, were around 67.18 and 62.02 kJ/mol. The frequency factor k0 calculated by the isothermal treatment is equal to 1.24 109 s-1. In non-isothermal treatment, the numerical factor m and the Avrami parameter n is estimated to be approximately equal to 3 and 2.79 respectively. This value corresponding that the bulk nucleation with a constant number of nuclei was dominant in three-dimensional (polyhedron) controlled by interface reaction.

Citation

Ameur Ouali , , (2018), Heat treatment and kinetics of precipitation of β-Mg17Al12 phase in AZ91 Alloy, Results in Physics, Vol:10, Issue:, pages:6, ELSEVIER

Kaolin DD1 (from Djebel Debbagh, Guelma, Algeria), kaolin Tamazarte KT (from Jijel, Algeria) and magnesium oxide MgO mixtures with relative weight ratios of 59/29/12 have been studied in this work in order to obtain cordierite ceramics with the stoichiometric formula (2MgO
2Al2O3
5SiO2), by mixing raw materials abundant in Algeria. Thermogravimetric analysis and differential thermal analysis were carried out on powder from room temperature to 1300 C, at heating rates from 10 to 50 Cmin?1. The phases and their transformations were determined by X-ray diffraction for the mixture of kaolin (59 wt.% DD1 + 29 wt.% KT) and 12 wt.% of magnesium oxide powder treated at different temperatures between 900 and 1250 C for 2 h. The activation energies of -cordierite formation calculated from isothermal data were around 372 kJmol?1. The average Avrami parameter is found to be around 1.95 for each heating rate.

Citation

Ameur Ouali , , (2018), Synthesis and Thermal Behavior of Cordierite Ceramics from Algerian Kaolin and Magnesium Oxide, Acta Physica Polonica A, Vol:134, Issue:134, pages:4, the Polish Academy of Sciences

In this study, the dehydroxylation of Algerian halloysite (DD1) was studied using differential thermal analysis. Measurements of samples were performed between room temperature and 1400 C, at different heating rates of 10, 20, 30, 40 and 50 Cmin?1. The activation energy calculated from isothermal (using Johnson-Mehl-Avrami and Ligero methods) and non-isothermal treatments (using Kissinger-Akahira-Sunose) were 135 kJ/mol and 153 kJ/mol, respectively. The Avrami parameter obtained by method of Ligero and the m parameter (a numerical factor) obtained by Matusita method were 1.55 and 1.59, respectively. The results show that bulk nucleation was dominant in halloysite transformation, followed by three-dimensional growth of meta-halloysite. This growth is controlled by diffusion from a constant number of nuclei. The frequency factor calculated by the isothermal treatment is equal to 4:16  106 s?1.

Citation

Ameur Ouali , , (2018), Thermal Dehydroxylation Kinetics of Algerian Halloysite by Differential Thermal Analysis, Acta Physica Polonica A, Vol:134, Issue:134, pages:4, the Polish Academy of Sciences

In this study, the dehydroxylation of Algerian halloysite (DD1) was studied using differential thermal analysis. Measurements of samples were performed between room temperature and 1400 °C, at different heating rates of 10, 20, 30, 40 and 50 °C min-1. The activation energy calculated from isothermal (using Johnson-Mehl-Avrami and Ligero methods) and non-isothermal treatments (using Kissinger-Akahira-Sunose) were 135 kJ/mol and 153 kJ/mol, respectively. The Avrami parameter obtained by method of Ligero and the m parameter (a numerical factor) obtained by Matusita method were 1.55 and 1.59, respectively. The results show that bulk nucleation was dominant in halloysite transformation, followed by three-dimensional growth of meta-halloysite. This growth is controlled by diffusion from a constant number of nuclei. The frequency factor calculated by the isothermal treatment is equal to 4.16 *106 s-1. DOI: 10.12693/APhysPolA.134.79 PACS/topics: differential thermal analysis (DTA)

Citation

MENAD Heraiz , Foudil SAHNOUNE , Ameur Ouali , Amina Raghdi, Djida Redaoui, , (2018), Thermal Dehydroxylation Kinetics of Algerian Halloysite by Differential Thermal Analysis, ACTA PHYSICA POLONICA A, Vol:134, Issue:1, pages:79-81, POLISH ACAD SCIENCES INST PHYSICS

In the present work, the thermal decomposition kinetics of Algerian halloysite (DD1) was examined under isothermal and non- isothermal conditions by thermogravimetric (TGA). Thermogravimetric TGA and differential thermal analysis (DTA) experiments were realized out between room temperature and 1400 °C, at different heating rates from 15 to 50 °C/min. The activation energies of this thermal decomposition process were calculated by DTG from isothermal treatments using Johnson-Mehl-Avrami (JMA) and Ligero methods and by non-isothermal treatments using Ozawa, Boswell and Kissinger methods, were 150 and 177 kJ/mol, respectively. The Avrami parameter of growth morphology n (indicating the crystallization mode) obtained by ligero method and the m parameter (a numerical factor) obtained by Matusita method was 1.55 and 1.59 respectively. The results showed that bulk nucleation was dominant in halloysite transformation followed by three-dimensional growth of meta-halloysite this growth is controlled by diffusion from a constant number of nuclei. The frequency factor calculated by the isothermal treatment is equal to 2×107s−1 Keywords : halloysite , decomposition process, dtg, activation energy, growth morphology

Citation

MENAD Heraiz , Foudil SAHNOUNE , Ameur Ouali , ,(2018), Investigation of the thermal behavior and decomposition kinetics of halloysite,International conference on Technology, Engineering and Sciences (IConTES),Antalya – Turkey

Kaolin DD1 (from Djebel Debbagh, Guelma, Algeria), kaolin Tamazarte KT (from Jijel, Algeria) and magnesium oxide MgO mixtures with relative weight ratios of 59/29/12 have been studied in this work in order to obtain cordierite ceramics with the stoichiometric formula (2MgO
2Al2O3
5SiO2), by mixing raw materials abundant in Algeria. Thermogravimetric analysis and differential thermal analysis were carried out on powder from room temperature to 1300 C, at heating rates from 10 to 50 Cmin?1. The phases and their transformations were determined by X-ray diffraction for the mixture of kaolin (59 wt.% DD1 + 29 wt.% KT) and 12 wt.% of magnesium oxide powder treated at different temperatures between 900 and 1250 C for 2 h. The activation energies of -cordierite formation calculated from isothermal data were around 372 kJmol?1. The average Avrami parameter is found to be around 1.95 for each heating rate. DOI: 10.12693/APhysPolA.134.71 PACS/topics: ceramics, differential thermal analysis, powders

Citation

Foudil SAHNOUNE , Ameur Ouali , Djida Redaoui, N. Saheb, , (2018), Synthesis and Thermal Behavior of Cordierite Ceramics from Algerian Kaolin and Magnesium Oxide, Acta Physica Polonica A, Vol:134, Issue:1, pages:71-74, POLISH ACAD SCIENCES INST PHYSICS

Thermal reactions and sintering behavior of kaolin DD3 (Djebel Debbagh, Algeria) and CaO mixtures to obtain dense anorthite ceramics were investigated. Mixed powders were uniaxially pressed and fired between 850 and 1150 C. Firing the pressed specimens yielded a dense anorthite ceramics. The sintered density increased with increase of CaO content and reached the maximum value of 2.57 g/cm3 for the composition containing 10 wt% CaO and fired at 1150 C. Their coefficient of linear expansion of the sintered samples at 1100 C decreases with the addition of CaO. X-ray diffraction experiments carried out on the samples containing varied amount of CaO and fired at the temperatures higher than 1000 C for 2 h showed the presence of only anorthite phase.

Citation

Ameur Ouali , , (2017), Effet of CaO addition on the sintering behavior of anorthite formed from kaolin and CaO, Acta Physica Polonica A, Vol:131, Issue:131, pages:4, POLISH ACADEMY OF SCIENCES

The effect of additional Mg on the microstructure, mechanical properties, and transformation kinetics during aging in Al–3.3 wt.% Cu alloy was studied. The compositions and microstructure were examined by X-ray diffraction, Differential scanning calorimetry (DSC) and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results show that the Mg in the Al–Cu alloy mainly precipitated to the grain boundaries during the process of transformation and formed a ternary Al2CuMg metallic compound and the rate of discontinuous precipitation reaction decreases with increasing concentration of Mg. The activation energy of crystallization was evaluated by applying the Kissinger equation.

Citation

Ameur Ouali , , (2017), Effect of Mg contents on the mechanical proprieties and precipitation kinetics in Al–3.3 wt.% Cu alloy, Metallurgical and Materials Engineering, Vol:23, Issue:4, pages:10, the Association of Metallurgical Engineers of Serbia.

The kinetics of spinel (Al–Si) crystallization from Algerian halloysite (DD1) was investigated using differential thermal analysis. Experiments were carried out on samples between room temperature and 1400 C with constant heating rate from 2 to 20 C min?1. The activation energies measured from isothermal and non-isothermal treatments were 1054.85 and 1140 kJ mol?1, respectively, for the spinel (Al–Si) formation. The Avrami constant n obtained by the Ligero method and the m parameter obtained by the Matusita method were about 2 for spinel crystallization. This value indicates that the crystallization mechanism of Al–Si spinel phase proceeds by bulk nucleation of the phase formation with a constant number of nuclei and that the three-dimensional growth of crystals is controlled by diffusion.

Citation

Ameur Ouali , , (2017), The kinetics of spinel formation of Algerian halloysite by differential thermal analysis., Acta Physica Polonica A, Vol:131, Issue:131, pages:4, the Polish Academy of Sciences

In this work, mullite-zirconia composite were fabricated by reaction sintering of Algerian halloysite Al2Si2O5(OH)4, boehmite Al(OOH), and zirconia (ZrO2) powder using conventional heating. The appropriate amount of the three raw powders was ball milled for 5 h and sintered between 1250 and 1650 C for 2 h. A scanning electron microscope was used to characterize the microstructure of sintered samples. A dilatometer and X-ray diffractometer were used to analyze the formation and transformation of phases. It is found that for the addition of zirconia up to 20wt.% the zirconia phase retains its tetragonal structure. The formation of primary mullite in all samples was complete at 1220 C. The cristobalite started to form at 1350 C, and disappeared at 1500 C in the samples of mullite, and at 1450 C when ZrO2 was added. The zircon compound ZrSiO4 started to form at 1350 C and completely disappeared at 1550 C. The increase in ZrO2 ratio promoted the formation of grains with a spherical shape.

Citation

Ameur Ouali , , (2017), Preparation and Phase Transformation of Mullite-Zirconia from Boehmite and Algerian Halloysite, Acta Physica Polonica A, Vol:131, Issue:, pages:4, the Polish Academy of Sciences

The kinetics of spinel (Al–Si) crystallization from Algerian halloysite (DD1) was investigated using differential thermal analysis. Experiments were carried out on samples between room temperature and 1400 °C with constant heating rate from 2 to 20 °C min-1. The activation energies measured from isothermal and non-isothermal treatments were 1054.85 and 1140 kJ mol-1, respectively, for the spinel (Al–Si) formation. The Avrami constant n obtained by the Ligero method and the m parameter obtained by the Matusita method were about 2 for spinel crystallization. This value indicates that the crystallization mechanism of Al–Si spinel phase proceeds by bulk nucleation of the phase formation with a constant number of nuclei and that the three-dimensional growth of crystals is controlled by diffusion. DOI: 10.12693/APhysPolA.131.139 PACS/topics: 81.70.Pg, 81.20.Ev, 82.20.–w

Citation

MENAD Heraiz , Foudil SAHNOUNE , Ameur Ouali , A .Raghdi, , (2017), The Kinetics of Spinel Formation of Algerian Halloysite by Differential Thermal Analysis, ACTA PHYSICA POLONICA A, Vol:131, Issue:1, pages:139-142, POLISH ACAD SCIENCES INST PHYSICS

In this work, mullite-zirconia composite were fabricated by reaction sintering of Algerian halloysite Al2Si2O5(OH)4, boehmite Al(OOH), and zirconia (ZrO2) powder using conventional heating. The appropriate amount of the three raw powders was ball milled for 5 h and sintered between 1250 and 1650 °C for 2 h. A scanning electron microscope was used to characterize the microstructure of sintered samples. A dilatometer and X-ray diffractometer were used to analyze the formation and transformation of phases. It is found that for the addition of zirconia up to 20wt.% the zirconia phase retains its tetragonal structure. The formation of primary mullite in all samples was complete at 1220 °C. The cristobalite started to form at 1350 °C, and disappeared at 1500 °C in the samples of mullite, and at 1450 °C when ZrO2 was added. The zircon compound ZrSiO4 started to form at 1350 °C and completely disappeared at 1550 °C. The increase in ZrO2 ratio promoted the formation of grains with a spherical shape. DOI: 10.12693/APhysPolA.131.136 PACS/topics: 81.05.Mh, 68.37.hk, 07.85.Nc

Citation

MENAD Heraiz , Foudil SAHNOUNE , Ameur Ouali , Amina Raghdi, Djida Redaoui, , (2017), Preparation and Phase Transformation of Mullite-Zirconia from Boehmite and Algerian Halloysite, ACTA PHYSICA POLONICA A, Vol:131, Issue:1, pages:136-138, POLISH ACAD SCIENCES INST PHYSICS

Thermal reactions and sintering behavior of kaolin DD3 (Djebel Debbagh, Algeria) and CaO mixtures to obtain dense anorthite ceramics were investigated. Mixed powders were uniaxially pressed and fired between 850 and 1150 °C. Firing the pressed specimens yielded a dense anorthite ceramics. The sintered density increased with increase of CaO content and reached the maximum value of 2.57 g/cm3 for the composition containing 10 wt% CaO and fired at 1150 °C. Their coefficient of linear expansion of the sintered samples at 1100 °C decreases with the addition of CaO. X-ray diffraction experiments carried out on the samples containing varied amount of CaO and fired at the temperatures higher than 1000 °C for 2 h showed the presence of only anorthite phase. DOI: 10.12693/APhysPolA.131.159 PACS/topics: 81.05.Je, 81.05.Mh, 81.20.Ev, 81.70.Pg, 65.40.De, 65.60.+a

Citation

Ameur Ouali , Foudil SAHNOUNE , MENAD Heraiz , , (2017), Effect of CaO Addition on the Sintering Behaviour of Anorthite Formed from Kaolin and CaO, ACTA PHYSICA POLONICA A, Vol:131, Issue:1, pages:159-161, POLISH ACAD SCIENCES INST PHYSICS

The effect of additional Mg on the microstructure, mechanical properties, and transformation kinetics during aging in Al–3.3 wt.% Cu alloy was studied. The compositions and microstructure were examined by X-ray diffraction, Differential scanning calorimetry (DSC) and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results show that the Mg in the Al–Cu alloy mainly precipitated to the grain boundaries during the process of transformation and formed a ternary Al2CuMg metallic compound and the rate of discontinuous precipitation reaction decreases with increasing concentration of Mg. The activation energy of crystallization was evaluated by applying the Kissinger equation.

Citation

Ameur Ouali , Foudil SAHNOUNE , M. Fatmi, A. Djemli, T. Chihi, M.A. Ghebouli, , (2017), Effect of Mg contents on the mechanical proprieties and precipitation kinetics in Al–3.3 wt.% Cu alloy, Metallurgical and Materials Engineering, Vol:23, Issue:4, pages:335-345, Association of Metallurgical Engineers of Serbia AMES

In this paper, we investigate the effect of MgO additions on the formation and densification behaviour of the cordierite obtained from some mixtures of Algerian kaolin and magnesium hydroxide. The sintering properties of these compositions have been evaluated by X-ray diffraction and bulk density. XRD analysis revealed that themajor phase of the synthesized ceramics was cordierite along with a trace of spinel. Firing the pressed specimens at 1400°C for 1 hour yielded a dense cordierite ceramics with a relative density higher than 96%, a negligible open porosity and a lower linear thermal expansion coefficient of 2.73×10−6 K−1 between 200 and 800°C. Cordierite due to its very low coefficient of thermal expansion is considered as promising candidate for advanced applications.

Citation

Ameur Ouali , , (2016), Sinterability and Thermal Properties of Cordierite Ceramics Prepared from Algerian Kaolinite and Magnesium Hydroxide, Molecular Crystals and Liquid Crystals, Vol:628, Issue:628, pages:7, Taylor & Francis Group

The excellent electrical, thermal and mechanical properties, and good stability of mullite made it a candidate material to produce ceramics for advanced applications such as catalyst supports, filters, optical devices, heat exchangers and electronic packaging. In this work, monolithic mullite was synthesized from kaolinite and boehmite and the kinetics of its formation was investigated using dilamometry. The activation energies for the transformation of kaolinite to metakaolinite, transformation of metakaolinite to spinel, and transformation of the kaolinite-boehmite powder to mullite were evaluated through non-isothermal treatment following the Kissinger and Ozawa equations. The growth morphology parameters were evaluated for the transformation of metakaolinite to spinel, and for the transformation of the spinel to mullite.

Citation

Ameur Ouali , , (2016), Kinetics of mullite formation from kaolinite and Boehmite, Molecular Crystals and Liquid Crystals, Vol:628, Issue:1, pages:10, Taylor & Francis Group

The excellent electrical, thermal and mechanical properties, and good stability of mullitemade it a candidate material to produce ceramics for advanced applications such as catalyst supports, filters, optical devices, heat exchangers and electronic packaging. In thiswork, monolithic mullite was synthesized from kaolinite and boehmite and the kinetics of its formation was investigated using dilamometry. The activation energies for the transformation of kaolinite to metakaolinite, transformation of metakaolinite to spinel, and transformation of the kaolinite-boehmite powder to mullite were evaluated through non-isothermal treatment following the Kissinger and Ozawa equations. The growth morphology parameters were evaluated for the transformation of metakaolinite to spinel, and for the transformation of the spinel to mullite.

Citation

MENAD Heraiz , Foudil SAHNOUNE , Ameur Ouali , M. Hrairi,, N. Saheb, , (2016), Kinetics of mullite formation from kaolinite and Boehmite, Molecular Crystals and Liquid Crystals, Vol:628, Issue:1, pages:55-64, TAYLOR & FRANCIS LTD

In this paper, we investigate the effect of MgO additions on the formation and densification behaviour of the cordierite obtained from some mixtures of Algerian kaolin and magnesium hydroxide. The sintering properties of these compositions have been evaluated by X-ray diffraction and bulk density. XRD analysis revealed that themajor phase of the synthesized ceramics was cordierite along with a trace of spinel. Firing the pressed specimens at 1400°C for 1 hour yielded a dense cordierite ceramics with a relative density higher than 96%, a negligible open porosity and a lower linear thermal expansion coefficient of 2.73×10−6 K−1 between 200 and 800°C. Cordierite due to its very low coefficient of thermal expansion is considered as promising candidate for advanced applications.

Citation

Ameur Ouali , Foudil SAHNOUNE , MENAD Heraiz , Belhouchet, , (2016), Sinterability and Thermal Properties of Cordierite Ceramics Prepared from Algerian Kaolinite and Magnesium Hydroxide, Molecular Crystals and Liquid Crystals, Vol:628, Issue:1, pages:65-71, TAYLOR & FRANCIS LTD

The influence of MgO addition on the structure and properties of mullite prepared through reaction sintering of Algerian kaolin and Al2O3 was investigated. The raw powders were wet ball milled, dried and cold compacted using a uniaxial press. The green compacts were sintered 8 hours at 1600 and 1650°C. The microstructure of samples was characterized using a scanning electron microscope. Mechanical and thermal properties were characterized using Vicker’s hardness tester, a universal testing machine and a dilatometer. It was found that the increase of MgO content from 0 to 3 wt-% increased the hardness of samples sintered 8 hours at 1600°C from 1039 to 1316.57 HV. Also, the increase of MgO content in samples sintered 8 hours at 1600 and 1650°C increased the compressive strength up to a maximum then decreased it. For a sintering temperature of 1600°C, the increase of MgO content up to 2 wt-% increased the flexural strength, but a further increase of MgO to 3 wt-% decreased it again, while for a sintering temperature of 1650°C, the increase of MgO content from 0 to 3 wt-% increased the flexural strength from 103.45 to 472.25 MPa. Amongst MgO containing samples, the increase of MgO content increased the coefficient of thermal expansion; however, it remained lower than the coefficient of thermal expansion of the sample without MgO addition.

Citation

Ameur Ouali , , (2013), 5. Effect of MgO addition on the mechanical and thermal properties of mullite synthesized through reaction sintering of Al2O3 and Algerian kaolin, American Journal of Modern Physics, Vol:2, Issue:5, pages:6, Sciences Publishing Group

We present a review on superconducting composite materials. The large variety of presented couples, from metal/HTS to polymer/HST and oxide/HTS, shows the great possibilities offered by these kinds of composites.This review is focused on “oxide/oxide” superconducting composites to illustrate the potentialities of this new variety of materials. From our own results, Bi2Sr3CaO7/Bi-2212 (or BiPb-2223) is a promising couple of oxides, which presents interesting features in view of applications for bolometers and magnetisation processes.

Citation

Ameur Ouali , , (2000), 4. High-Tc super conductor oxide/oxide composite materials: a review and some results in the system "Bi-based HTS cuprates/ insulating oxides, Journal of Optoelectronics and Advanced Materials, Vol:2, Issue:5, pages:8, INOE Publishing House

Preparation of Bi-2223/Bi-2310 and Bi-2212/BiFeO3 composites has been performed so as to obtain some active composites where the superconductive properties of Bi-2223 or Bi-2212 can be modified using a property of the insulating phase. In both cases superconductive percolation was obtained, but only in the case of a Bi-2223 (or Bi-2212)/Bi-2310 composite was no (or very weak) chemical reaction observed during sintering. Since the superconductive percolation threshold was obtained in this case for a concentration of Bi-2223 or Bi-2212 lower than 20%, a special composite model had to be considered. The Bi-2212/BiFeO3 system is very interesting due to the ferroic properties of BiFeO3. Superconductive percolation was achieved with this mixture too, but with more difficulties because of a chemical reaction occurring between the two compounds during sintering. A study of the properties of these composites has been performed and will be briefly described in what follows. The good quality of the Bi-2223(or Bi-2212)/Bi-2310 composite enables us to expect some future applications.

Citation

Ameur Ouali , , (2000), 3. Superconductive percolation in Bi-based superconductor/Bi-based insulator composites: case of Bi-2223/Bi-2310 and Bi-2212/BiFeO3, Superconductor Science and Technology, Vol:13, Issue:8, pages:7, IOP Science

Complexes of the M(en)3Ag2(CN)4 (M = Ni, Zn, Cd) and M(en)2Ag2(CN)4 (M = Ni, Cu, Zn, Cd) type were prepared and identified by elemental analysis, infrared spectroscopy, measurement of magnetic susceptibility, and X-ray powder diffractometry. The crystal structures of Ni(en)3Ag2(CN)4 (I) and Zn(en)2Ag2(CN)4 (II) were determined by the method of monocrystal structure analysis. Complex I crystallizes in the space group C2/c, a = 1.2639(5), b = 1.3739(4), c = 1.2494(4) nm, β = 113.25(4)°, Dm = 1.86(1), Dc = 1.86 gcm−3 Z = 4, R = 0.0429. The crystal structure of I consists of complex cations [Ni(en)3]2+ and complex anions [Ag(CN)2]−. Complex II crystallizes in the space group I2/m, a = 0.9150(3), b = 1.3308(4), c = 0.6442(2) nm, β = 95.80(3)°, Dm = 2.14(1), Dc = 2.15 gcm−3, Z = 2, R = 0.0334. Its crystal structure consists of infinite, positively charged chains of the [-NCAgCNZn- (en)2]nn+ type and isolated [Ag(CN)2]− anions. The atoms of Ag are positioned parallely to the z axis and the AgAg distance is equal to 0.3221(2) nm.

Citation

Ameur Ouali , , (1988), 2. Preparation, structure and properties of dicyano silver complex of the M(en)3Ag2(CN)4 and M(en)2Ag2(CN)4 type, Inorganica Chimica Acta, Vol:147, Issue:2, pages:9, science direct

ABSTRACT Using DTA/TG thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), crystallization kinetics of -cordierite ceramic from MgO–Al2O3–SiO2– TiO2 glasses obtained through melt cooling are presented. Under 40 cm3/min argon gas flow, DTA experiments were carried out on samples ranging from room temperature to 1400 °C. This study utilized heating rates of 10, 20, 30, 40, and 50 °C/min. The sintered powders' phase transformations were characterized by XRD. Using DTA results, the activation energy values for cordierite formation were measured under both non-isothermal (Kissinger, Boswell, and Ozawa methods) and non-isothermal (Johnson–Mehl–Avrami (JMA) theory) treatments of 845 and 720 kJ mol-1, respectively. When non-isothermal treatments were used, the growth morphology parameters n (the Avrami parameter) were found to be close to 1.5, when isothermal treatments were used (the Ligero method), and Matusita et al. found that m (the numerical factor) was 1.5. The fact that the growth morphology parameters n and m are approximately 1.5 indicates a diffusion-controlled polyhedron-like three-dimensional growth from a constant number of nuclei. Keywords: Cordierite, Differential thermal analysis, Avrami parameter, Activation energy

Citation

Foudil SAHNOUNE , Ameur Ouali , smail LAMARA , ,(0023-10-30), Crystallization Kinetics Study of α-Cordierite from MgO– Al2O3–SiO2–TiO2,10th INTERNATIONAL CONFERENCE ON COMPUTATIONAL AND EXPERIMENTAL SCIENCE AND ENGINEERING (ICCESEN-2023) 27-30 October 2023, ANTALYA-TURKEY,ANTALYA-TURKEY