The objective of this work is a dilatometric study of Al + 0.1% of multiwall carbon nanotubes nan... more The objective of this work is a dilatometric study of Al + 0.1% of multiwall carbon nanotubes nanocomposite material (NCM) in three directions: X-parallel to the rolling direction; Y-perpendicular to the rolling direction and (Z) perpendicular to the ribbon plane. NCM specimens were made in the form of a 0.1-mm-thick ribbon. The temperature range used for measurements was 20°C to 600°C. The obtained results show that presence of nanotubes affects the thermal expansion coefficient (TEC) measured in different directions. α x (T) and α y (T)-TEC plots as a function of temperature along X and Y directions, respectively-have substantially the same shape and overlap in the area of 400°C. The expansion along X-axis becomes greater than along Y-axis below this temperature value. It is clear that the coefficient α z (T) is lower than α x (T) and α y (T) over the entire temperature range. The expansion along Z-axis is smaller compared to that along X-and Y-axes. This behaviour suggests that there is a strong interatomic interaction along this direction (Z). α z (T) becomes monotonous and constant and is equal to 8 × 10 −6°C−1 at temperatures above 300°C. Such order of magnitude had not been obtained in earlier studies of aluminium alloys. The obtained TEC shows high anisotropy, which grows with the increase of temperature. The heat flow (differential scanning calorimetry, (DSC)) of Al + 0.1% carbon nanotubes (CNT) NCM is more intense compared to that of pure aluminium produced in similar conditions. The two representative curves have similar shape and are almost entirely overlapped. The thermogravimetry results confirm those of DSC. The Raman spectrum of this nanomaterial shows that intensity of G and D bonds is significantly increased compared to that of the pure material. The infrared diagram also confirms that in this case the mentioned bonds are more intensive NCM. The tensile strength measurements (σB) of the studied NCM also demonstrate that its value increases from 140 ± 10 MPa for Al without nanotubes to 200 ± 10 MPa for NCM.
The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a ... more The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA) at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a commensurate transformation of the material.
The numerous studies conducted on the structure of CaFeO 2.5 showed that the material undergoes a... more The numerous studies conducted on the structure of CaFeO 2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO 2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO 2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA) at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a commensurate transformation of the material.
This work presents the results of our research of the structure and practically important charact... more This work presents the results of our research of the structure and practically important characteristics of a nanocomposite material on the basis of nanoporous carbon and thermally exfoliated graphite. This work shows that the use of the abovementioned composition in electrodes for supercapacitors allows to attain the level of their specific electrical capacitance at (155...160) F/g.
The set of composite materials that consist of micro/nanocellulose and complex K 2 Eu(MoO 4)(PO 4... more The set of composite materials that consist of micro/nanocellulose and complex K 2 Eu(MoO 4)(PO 4) luminescent oxide particles was prepared. The composites were studied by means of scanning electron microscopy, XRD analysis, dilatometry, differential scanning calorimetry and thermogravimetric analysis, and dielectric and luminescence spectroscopy. Dependencies of density, crystallinity, relative extension, thermal extension coefficient, dielectric relaxation parameters, intensity and shape of photoluminescence bands on temperature, and content of oxide component were studied. The structure of the composite without oxide is formed by grains of nearly 5-50 μm in size (crystallinity is about~56%). Structure of the micro/nanocellulose samples which contain oxide particles is similar, but the cellulose grains are deformed by oxide particles. Dependencies of the abovementioned properties on temperature and oxide content were analyzed together with data on the size distribution of oxide particles for the samples for various oxide and molecules of water concentrations.
The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) ... more The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) on the thermomechanical and structural properties of high-density polyethylene. Several, complementary experimental techniques were used, namely, dilatometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and infrared (IR) spectroscopy. Dilatometry data showed that nanocomposites exhibit anisotropic behavior, and intensity of the anisotropy depends on the MWCNT concentration. The shapes of the dilatometric curves of the nanocomposites under study differ significantly for the radial and longitudinal directions of the samples. DSC results show that MWCNTs weekly influence calorimetry data, while Raman spectra show that the I D /I G ratio decreases when MWCNT concentration increases. The IR spectra demonstrate improvement of the crystallinity of the samples as the content in MWCNTs rises.
In this work, we studied a nanocomposite material made from fluoroplastic which contains 20 wt.% ... more In this work, we studied a nanocomposite material made from fluoroplastic which contains 20 wt.% multi-walled nanotubes. In order to complete the present work, we have used different thermodynamic and mechanical techniques. The introduction of nanotubes in the F4 polymer matrix has completely changed the tribological and thermodynamic properties of the studied nanocomposite material. The compression strength becomes 20% higher than that of the F4 polymer matrix. Meanwhile the wear resistance achieves an order of magnitude 100 times greaterthan that of F4. Moreover, a friction coefficient is about 25% to 30% lower than that of a similar material and especially that of F4 material. Differential scanning calorimetric study showed that the glassy phase transition appears at about 330°C, which confirms that the degradation of the studied nanocomposite occurs at relatively higher temperature. This result confirms the one concerning the change in tribological properties. Dilatometric study revealed that the thermal expansion coefficient has been increased. The observed relative elongation measurement change depends on the direction along which the measurement has been done and confirms, in turn, the anisotropic character of the studied material. These results suggest that the metallic materials could be replaced by nanocomposite compounds which present good physical properties.
L’objectif de cette note est l’etude de l’influence de l’epaisseur d’une tole, d’un alliage Al-M... more L’objectif de cette note est l’etude de l’influence de l’epaisseur d’une tole, d’un alliage Al-Mg-Si, sur le coefficient de dilatation thermique. Cette tole contient d’autres elements d’addition. Trois echantillons ont ete preleves orientes selon les directions parallele, perpendiculaire a la direction de laminage dans le plan de laminage et la troisieme est perpendiculaire au plan de laminage (direction Z ). Les resultats obtenus montrent que les comportements dilatometriques changent fortement avec l’epaisseur. Le coefficient de dilatation thermique suivant la direction Z de la tole d’epaisseur 1.35mm est tres faible devant ceux des deux toles d’epaisseur 1.15et 1mm.
L’objectif de cet article est l’etude de l’influence de l’epaisseur sur le coefficient de dilatat... more L’objectif de cet article est l’etude de l’influence de l’epaisseur sur le coefficient de dilatation thermique de la tole AlMgSi. Les resultats obtenus dependent fortement de l’epaisseur. Les courbes dilatometriques varient d’une direction a une autre. Il y a presence d’une anisotropie dont l’intensite depend de l’epaisseur et de la direction de mesure. L’echantillon preleve selon la direction Y et dont l’epaisseur est de 1.15mm presente une dilatation faible devant les autres. Ce comportement le rend interessant dans le domaine industriel.
L’objectif de ce travail est l’etude par la calorimetrie differentielle de quatre echantillons a ... more L’objectif de ce travail est l’etude par la calorimetrie differentielle de quatre echantillons a base de fluoroplastique contenant differentes concentrations en graphite thermiquement dilate (GTD) a diverses dispersions. Nous avons remarque que la vitesse de chauffage joue un role tres important. L’augmentation de la vitesse de chauffage, de 5 a 10 puis a 15°C/mn, modifie le comportement calorimetrique de notre nanocomposite quelque soit la concentration et/ou la dispersion. Toutes les courbes contiennent chacune une anomalie calorimetrique dont la forme et l’intensite dependent de la concentration et de la dispersion. La temperature d’apparition de cette anomalie calorimetrique change d’un echantillon a un autre. Nous avons montre que le nanomateriau contenant la plus petite concentration en GTD et possedant une dispersion elevee se degrade aux hautes temperatures lorsqu’il est chauffe avec la plus grande vitesse. Il est le plus resistant aux chocs thermiques. L’introduction du GTD...
Les éléments d'addition tels que : W, Mo, Mn …, jouent un rôle important dans la préoxydatio... more Les éléments d'addition tels que : W, Mo, Mn …, jouent un rôle important dans la préoxydation des alliages dentaires et par conséquent, sur la qualité de la liaison céramique /métal. Cette étude porte sur l'effet de l'addition de tungstène sur l'état microstructural des alliages Co-Cr, avant le processus de céramisation. Ces alliages ont été obtenus par solidification dirigée. Leur caractérisation, au moyen essentiellement la microscopie électronique à transmission (MET) et la diffraction des rayons X, montre que l'addition du tungstène jusqu'à 8 % en poids implique des transformations structurales, intimement liées au pourcentage de cet élément contenu dans l'alliage.
The objective of this work is a dilatometric study of Al + 0.1% of multiwall carbon nanotubes nan... more The objective of this work is a dilatometric study of Al + 0.1% of multiwall carbon nanotubes nanocomposite material (NCM) in three directions: X-parallel to the rolling direction; Y-perpendicular to the rolling direction and (Z) perpendicular to the ribbon plane. NCM specimens were made in the form of a 0.1-mm-thick ribbon. The temperature range used for measurements was 20°C to 600°C. The obtained results show that presence of nanotubes affects the thermal expansion coefficient (TEC) measured in different directions. α x (T) and α y (T)-TEC plots as a function of temperature along X and Y directions, respectively-have substantially the same shape and overlap in the area of 400°C. The expansion along X-axis becomes greater than along Y-axis below this temperature value. It is clear that the coefficient α z (T) is lower than α x (T) and α y (T) over the entire temperature range. The expansion along Z-axis is smaller compared to that along X-and Y-axes. This behaviour suggests that there is a strong interatomic interaction along this direction (Z). α z (T) becomes monotonous and constant and is equal to 8 × 10 −6°C−1 at temperatures above 300°C. Such order of magnitude had not been obtained in earlier studies of aluminium alloys. The obtained TEC shows high anisotropy, which grows with the increase of temperature. The heat flow (differential scanning calorimetry, (DSC)) of Al + 0.1% carbon nanotubes (CNT) NCM is more intense compared to that of pure aluminium produced in similar conditions. The two representative curves have similar shape and are almost entirely overlapped. The thermogravimetry results confirm those of DSC. The Raman spectrum of this nanomaterial shows that intensity of G and D bonds is significantly increased compared to that of the pure material. The infrared diagram also confirms that in this case the mentioned bonds are more intensive NCM. The tensile strength measurements (σB) of the studied NCM also demonstrate that its value increases from 140 ± 10 MPa for Al without nanotubes to 200 ± 10 MPa for NCM.
The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a ... more The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA) at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a commensurate transformation of the material.
The numerous studies conducted on the structure of CaFeO 2.5 showed that the material undergoes a... more The numerous studies conducted on the structure of CaFeO 2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO 2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO 2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA) at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a commensurate transformation of the material.
This work presents the results of our research of the structure and practically important charact... more This work presents the results of our research of the structure and practically important characteristics of a nanocomposite material on the basis of nanoporous carbon and thermally exfoliated graphite. This work shows that the use of the abovementioned composition in electrodes for supercapacitors allows to attain the level of their specific electrical capacitance at (155...160) F/g.
The set of composite materials that consist of micro/nanocellulose and complex K 2 Eu(MoO 4)(PO 4... more The set of composite materials that consist of micro/nanocellulose and complex K 2 Eu(MoO 4)(PO 4) luminescent oxide particles was prepared. The composites were studied by means of scanning electron microscopy, XRD analysis, dilatometry, differential scanning calorimetry and thermogravimetric analysis, and dielectric and luminescence spectroscopy. Dependencies of density, crystallinity, relative extension, thermal extension coefficient, dielectric relaxation parameters, intensity and shape of photoluminescence bands on temperature, and content of oxide component were studied. The structure of the composite without oxide is formed by grains of nearly 5-50 μm in size (crystallinity is about~56%). Structure of the micro/nanocellulose samples which contain oxide particles is similar, but the cellulose grains are deformed by oxide particles. Dependencies of the abovementioned properties on temperature and oxide content were analyzed together with data on the size distribution of oxide particles for the samples for various oxide and molecules of water concentrations.
The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) ... more The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) on the thermomechanical and structural properties of high-density polyethylene. Several, complementary experimental techniques were used, namely, dilatometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and infrared (IR) spectroscopy. Dilatometry data showed that nanocomposites exhibit anisotropic behavior, and intensity of the anisotropy depends on the MWCNT concentration. The shapes of the dilatometric curves of the nanocomposites under study differ significantly for the radial and longitudinal directions of the samples. DSC results show that MWCNTs weekly influence calorimetry data, while Raman spectra show that the I D /I G ratio decreases when MWCNT concentration increases. The IR spectra demonstrate improvement of the crystallinity of the samples as the content in MWCNTs rises.
In this work, we studied a nanocomposite material made from fluoroplastic which contains 20 wt.% ... more In this work, we studied a nanocomposite material made from fluoroplastic which contains 20 wt.% multi-walled nanotubes. In order to complete the present work, we have used different thermodynamic and mechanical techniques. The introduction of nanotubes in the F4 polymer matrix has completely changed the tribological and thermodynamic properties of the studied nanocomposite material. The compression strength becomes 20% higher than that of the F4 polymer matrix. Meanwhile the wear resistance achieves an order of magnitude 100 times greaterthan that of F4. Moreover, a friction coefficient is about 25% to 30% lower than that of a similar material and especially that of F4 material. Differential scanning calorimetric study showed that the glassy phase transition appears at about 330°C, which confirms that the degradation of the studied nanocomposite occurs at relatively higher temperature. This result confirms the one concerning the change in tribological properties. Dilatometric study revealed that the thermal expansion coefficient has been increased. The observed relative elongation measurement change depends on the direction along which the measurement has been done and confirms, in turn, the anisotropic character of the studied material. These results suggest that the metallic materials could be replaced by nanocomposite compounds which present good physical properties.
L’objectif de cette note est l’etude de l’influence de l’epaisseur d’une tole, d’un alliage Al-M... more L’objectif de cette note est l’etude de l’influence de l’epaisseur d’une tole, d’un alliage Al-Mg-Si, sur le coefficient de dilatation thermique. Cette tole contient d’autres elements d’addition. Trois echantillons ont ete preleves orientes selon les directions parallele, perpendiculaire a la direction de laminage dans le plan de laminage et la troisieme est perpendiculaire au plan de laminage (direction Z ). Les resultats obtenus montrent que les comportements dilatometriques changent fortement avec l’epaisseur. Le coefficient de dilatation thermique suivant la direction Z de la tole d’epaisseur 1.35mm est tres faible devant ceux des deux toles d’epaisseur 1.15et 1mm.
L’objectif de cet article est l’etude de l’influence de l’epaisseur sur le coefficient de dilatat... more L’objectif de cet article est l’etude de l’influence de l’epaisseur sur le coefficient de dilatation thermique de la tole AlMgSi. Les resultats obtenus dependent fortement de l’epaisseur. Les courbes dilatometriques varient d’une direction a une autre. Il y a presence d’une anisotropie dont l’intensite depend de l’epaisseur et de la direction de mesure. L’echantillon preleve selon la direction Y et dont l’epaisseur est de 1.15mm presente une dilatation faible devant les autres. Ce comportement le rend interessant dans le domaine industriel.
L’objectif de ce travail est l’etude par la calorimetrie differentielle de quatre echantillons a ... more L’objectif de ce travail est l’etude par la calorimetrie differentielle de quatre echantillons a base de fluoroplastique contenant differentes concentrations en graphite thermiquement dilate (GTD) a diverses dispersions. Nous avons remarque que la vitesse de chauffage joue un role tres important. L’augmentation de la vitesse de chauffage, de 5 a 10 puis a 15°C/mn, modifie le comportement calorimetrique de notre nanocomposite quelque soit la concentration et/ou la dispersion. Toutes les courbes contiennent chacune une anomalie calorimetrique dont la forme et l’intensite dependent de la concentration et de la dispersion. La temperature d’apparition de cette anomalie calorimetrique change d’un echantillon a un autre. Nous avons montre que le nanomateriau contenant la plus petite concentration en GTD et possedant une dispersion elevee se degrade aux hautes temperatures lorsqu’il est chauffe avec la plus grande vitesse. Il est le plus resistant aux chocs thermiques. L’introduction du GTD...
Les éléments d'addition tels que : W, Mo, Mn …, jouent un rôle important dans la préoxydatio... more Les éléments d'addition tels que : W, Mo, Mn …, jouent un rôle important dans la préoxydation des alliages dentaires et par conséquent, sur la qualité de la liaison céramique /métal. Cette étude porte sur l'effet de l'addition de tungstène sur l'état microstructural des alliages Co-Cr, avant le processus de céramisation. Ces alliages ont été obtenus par solidification dirigée. Leur caractérisation, au moyen essentiellement la microscopie électronique à transmission (MET) et la diffraction des rayons X, montre que l'addition du tungstène jusqu'à 8 % en poids implique des transformations structurales, intimement liées au pourcentage de cet élément contenu dans l'alliage.
Uploads
Papers by S. Hamamda