International audienceLa méthode d’élaboration de poudre par flash combustion permet l’obtention ... more International audienceLa méthode d’élaboration de poudre par flash combustion permet l’obtention de poudres de taille nanométrique. Des quatre combustibles testés, ceux semblant mener le plus facilement à la formation de la phase recherchée (CaZrO3) sont la glycine et la ß-alanine. Ils conduisent à des poudres cristallisées après synthèse ainsi qu’à des éramiques relativement denses après frittage non optimisé
The purpose of this work is to decrease or eliminate porosities in electro-thermal explosion (ETE... more The purpose of this work is to decrease or eliminate porosities in electro-thermal explosion (ETE-VC) products with sintering additives. The Ti–C system has been synthesized for its advantages for refractory, abrasive and structural applications. We attempted to density TiC by using iron addition; this metal is introduced through a secondary reaction 3TiO3+Al. This mixture reacts exothermically ϪH298 = -1072.7 kJ and the heat is released according to by Fe addition 3TiO3+4Al+3C+xFe→3TiC+2Al2O3+xFe. .X-ray diffraction analysis indicated that intermetallic Fe3Al, TiC and Al2O3 are the main phases formed in the reinforced high-performance ceramic-matrix composites and the additions of Fe decreased the lattice parameter of TiC. Field emission scanning electron microscopy examinations showed that the addition of Fe decreased TiC particle size and changed their growth controlling mechanism. Also, Raman spectroscopy analysis showed that at higher Fe contents, oxygen dissolved in the TiC cr...
The present research is devoted to the optimization of the sintering schedule of Ba (Co0.7Zn0.3)1... more The present research is devoted to the optimization of the sintering schedule of Ba (Co0.7Zn0.3)1/3Nb2/3O3 (BCZN) dielectric ceramics for microwaves applications. A novel approach to the heat treatment of these ceramics based on the rapid-rate sintering (RRS) technique followed by a lower temperature annealing cycle has been developed. The relationships among the heat treatment process optimization, the structural, microstructural characteristics, and the microwave dielectric properties of the BCZN ceramics were investigated using X-ray diffraction, scanning electron microscopy, energy dispersion analysis, and vector network analysis. The RRS-technique shortens substantially the time required for the elaboration of these components in comparison with conventional sintering techniques and prevents simultaneously the formation of secondary phases as Ba5Nb4O15 and Ba8(Co, Zn) 1Nb6O24 on the surface of the ceramics. All of the sintered and annealed ceramics exhibit a high quality factor...
Matériaux pour l'électronique et dispositifs associés, 2015
Nombre de fonctions electroniques « passives » sont assurees par des composants realises par la t... more Nombre de fonctions electroniques « passives » sont assurees par des composants realises par la technologie ceramique : fonctions d’interconnexion, capacitives, resistives, inductives, de protection, capteurs (temperature, forces, deplacements, gaz…), etc. Les proprietes physiques des materiaux mis en œuvre, le plus souvent covalents, peuvent etre controlees par des substitutions dans la maille cristalline. La technologie ceramique permet egalement la realisation de microstructures inhomogenes et l’obtention de composants formes de plusieurs materiaux distincts tels les composants multicouches.
L'interet futur du marche des ceramiques pour resonateurs hyperfrequences porte sur de nouvea... more L'interet futur du marche des ceramiques pour resonateurs hyperfrequences porte sur de nouveaux materiaux de constante dielectrique e superieure a 50, caracterises par un bon facteur de qualite Q et un coefficient de stabilite en temperature τ f proche de 0 ppm/°C ou ajustable. Dans cette optique, nous nous sommes interesses aux proprietes dielectriques hyperfrequence de la phase perovskite metastable La 2/3 TiO 3 stabilisee par du nickel. Nous avons prepare des compositions (1-x)La 2/3 TiO 3 - xNiTiO 3 avec 0.01<x<0.15 par reaction en voie solide a partir des oxydes TiO 2 , La 2 O 3 , et NiO. Les temperatures de frittage, comprises entre 1320°C et 1380°C, ont ete determinees pour chaque composition par dilatometrie. La formation d'une phase isomorphe de La 2/3 TiO 3 a ete mise en evidence, en presence de phases secondaires, par diffraction des Rayons X et par observations microstructurales et analyses EDS realisees au microscope electronique a balayage. Les proprietes...
Magnesium titanate MgTiO3 is a well known compound for type I multilayer ceramic capacitors. Neve... more Magnesium titanate MgTiO3 is a well known compound for type I multilayer ceramic capacitors. Nevertheless the sintering temperature of the pure ilmenite MgTiO3 is around 1350°C. Such a high sintering temperature together with the high sensitivity of the dielectric material to reduction when heated in a low-oxygen containing atmosphere involve that MgTiO3-based MLCC include palladium-rich inner electrodes. The high level of variation of both the costs of Pd and Ag justifies researches leading to the use of cheaper metals such as silver or base metals such as nickel or copper. When using low-melting temperature metals (silver melts at 960°C and copper at 1085°C), the sintering temperature of the dielectric material has to be lowered. We report here on our investigations on the use of fluorine containing additives for the reducing of the sintering temperature of magnesium titanate, showing so the ability of this material to be sintered at temperatures much lower than 1000°C. Both diele...
Nanocomposites are wear resistant materials used in cutting tool applications. The materials are ... more Nanocomposites are wear resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo 2 C) 1-x (TiC) x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo 2 C-TiC was rapidly synthesised and simultaneously consolidated by Field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs as reinforcement of the CMNC's. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt.% SWCNTs from (Mo 2 C) 1-x (TiC) x , x= 0.2 which was sintered at 1700°C, 70 MPa for 10 min, M 0.8 T 0.2 / 1 Wt% SWCNTs exhibit a better density, highest hardness and a good ductility. Relative densification was achieved 99.5 % from the theoretical and a good mechanical properties like hardness and fracture toughness (K IC =5.6 Mpa m 1/2) are enhanced. The results were confirmed using Raman spectroscopy.
Nanocomposites are worn resistant materials used in cutting tool applications. The materials are ... more Nanocomposites are worn resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo2C)1-x–(TiC)x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo2C-TiC was rapidly synthesised and simultaneously consolidated by field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs was reinforcement of the NCMC’s. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and...
Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC... more Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC) ceramics matrix nanocomposites (CMNCs) tools were manufacturated by a field actived sparck plasma sintering processus (FASPS). The effects of cBN-TiC ratio, carbon nanotubes and optimisation of the sintering process on the microstructure, densification in addition mechanical and vibronic properties of NC-cBN-TiC nanocomposites were studied. The results showed that for the nanocomposite cBN-TiC vol. ratio of 8:2 with 0.1 wt% NC, it was found that microhardness incresses significantly with addition of carbon nanotubes exhibited the highest microhardness and fracture toughness. After sintering of the samples at 1800 °C, 10 mn, 75 MPa of cBN–TiC1-x, x=0.8 with and without addition of 0.1 wt% NC were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction. The samples exhibited a dense polycrystalline structure. From the resonant Raman scattering we can...
Biomedical Journal of Scientific & Technical Research, 2019
Nanocomposite Ti 50 wt% Nb with and without reinforcement of carbon nanotubes were successfully f... more Nanocomposite Ti 50 wt% Nb with and without reinforcement of carbon nanotubes were successfully fabricated by ball milling of Ti, Nb and SWCNTs nano powder mixture followed by field activated spark plasma sintering process (FASPS) for biomedical application, superconductivity and magnetism in the ITER Project. The use of brittle Ti powder, instead of ductile elemental powder, led to significant increment in the yield of mechanically alloyed powder. The powder consisted of homogeneously distributed nano-sized Ti/Nb particles together with micron-sized pure Nb particles. Sintering of the powders under low temperature and pressure conditions (1273 K, 1473 K and P=50 MPA) resulted in the fine-grained heterogeneous microstructure consisting of α and β phases. On the other hand, sintering at higher temperatures (1473 K) resulted in a relatively coarsegrained chemically homogeneous microstructure with almost complete phase. Coarse-grained homogeneous β TiNb alloy exhibited higher average hardness as compared to that of heterogeneous fine-grained microstructures. An attempt has been made to illustrate the correlation between the microstructural characteristics and mechanical properties of the sintered Ti50Nb compacts. To studies and to develop the influence of CNTs on the behavior of the nanocomposite TiNb/CNTs and the welding joint interface between TA6V and nanocomposite by Sparck plasma sintering. At last, the continuation of the work has been discussed and prepared, planning dynamic flexion tests to measure the TiNb, TiNb/CNTs, TiNb/CNTs,/TA6V fatigue limit and developing a computer processing chain in order to customize prostheses respecting patients' morphology. The fluid enhanced lubrification of the prosthesis articulation is currently also in preparation. the practice of joint replacement in both the knee and the hip to
International Journal of Applied Ceramic Technology, 2019
This paper is focusing basically on the ceramic technology, of which several methods for the synt... more This paper is focusing basically on the ceramic technology, of which several methods for the synthesis of MgAl 2 O 4 have been investigated. The synthesis conditions regarding the powders cleanliness, microstructure and sintering parameters of MgAl 2 O 4 were studied. MgAl 2 O 4 powder was synthesized via conventional solid-state route using different milling process: vertical attrition milling, WAB as a high-energy horizontal attrition milling and Pulverisette as a planetary ball miller, and via solution combustion route using Urea, Glycine and a mixture of Urea/Glycine. Urea and Glycine was used as fuel. The white powders was obtained for all solid-state routes and for Urea-combustion technique. The black and gray powders were obtained in the case of combustion technique, respectively, by using a fuel of Glycine and Glycine/Urea mixture. The obtained powders and pellets were characterized by XRD, SEM, and Dilatometry. The results show that, among all the solid-state route processes, wet attrition milling gives the better and clean spinel phase. The WAB milling and Pulverisette miller introduce a contamination by some yttria-stabilized zirconia balls in the corresponding powder. Further, the flash combustion technique permit to have nanoparticles with a dense spinel phase of MgAl 2 O 4 and with lower sintering temperature in less time and with no calcination step.
Environmental Engineering and Management Journal, 2017
The main objective of this study was to investigate the potential utilization of polyethylene ter... more The main objective of this study was to investigate the potential utilization of polyethylene terephthalate PET waste in cementitious matrix, as substituent to cement, to develop lightweight construction materials and for preventing chemical attacks or repairing various reinforced concrete structures. Composites containing different amounts of PET particles, as partial replacement to cement by weight, were characterized by destructive and non-destructive testing. So, the thermal conductivity, ultrasonic pulse velocity (UPV) and sorptivity coefficients of composite made up of mixtures of PET polymer were measured; the adverse environmental conditions are simulated by using various acid solutions. The corrosion process was monitored by measuring the mass loss and compressive strength for different periods. The experimental investigation revealed that the addition of PET particles reduces the UPV; furthermore, thermal conductivity and sorptivity of the composites have been decreased. So, the decrease of the sorptivity-value is favorable to the durability of the specimen structures. On behalf of the resistance to aggressive environments, it was found that the course of action of acid attack is dependent on the type of acid and solubility of the calcium salt formed. The presence of PET was found to lower the detrimental effect of acids on composite. Scanning electron microscope (SEM), X-ray diffraction and FT-IR analyses were used to better understand the cement hydration products of the deteriorated mortars. In this way, the obtained PET-mortar composites would appear to be low-cost materials which would contribute to resolving some of the solid waste problems in addition to conserving energy.
Le materiau (zr,sn)tio 4 est utilise pour la realisation de resonateurs hyperfrequences. L'ob... more Le materiau (zr,sn)tio 4 est utilise pour la realisation de resonateurs hyperfrequences. L'obtention de facteurs de merite qf superieurs ou egaux a 50000 ghz pour des frequences de resonance inferieures a 5 ghz, ainsi que le broyage des matieres premieres, poudres d'oxydes tio 2, zro 2 sno 2, la 2o 3 et nio, par un procede d'attrition utilisant un broyeur industriel dyno-mill sont mal maitrises. L'etude menee focalise alors sur la connaissance de l'etat de dispersion des barbotines, l'optimisation du broyage et des facteurs de merite des resonateurs et la comprehension des relations entre microstructures et proprietes dielectriques. Enfin le marche evoluant vers des materiaux avec des constantes dielectriques plus grandes, une etude sur des compositions la 2 / 3tio 3 stabilise au nickel a ete menee. L'etat de dispersion des barbotines aqueuses de poudres d'oxydes, en fonction de la charge en solide et du ph, a ete caracterise par rheologie et mesure du potentiel zeta. Il en resulte que les barbotines de charge en solide de 50% en masse sont stables, defloculees pour des ph superieurs a 10,5. Dans ces conditions les barbotines presentent des valeurs de viscosite suffisamment faibles pour permettre le broyage par attrition avec le dyno-mill. L'influence des autres etapes technologiques, et notamment le frittage, sur les proprietes dielectriques a ete etudiee. Des recuits realises a 1250\\c apres frittage permettent d'ameliorer les facteurs de qualite des resonateurs d'environ 20%. Les observations microstructurales realisees par diffraction des rx, meb, eds et analyses d'images ont permis de montrer que les ceramiques sont polyphasees et que certaines phases diffusent vers la surface lors du recuit. Les resonateurs zst synthetises presentent alors de tres bonnes et reproductibles caracteristiques dielectriques : = 37,5,qf = 50000 ghz mesure a 4 ghz, f proche 0 ppm/\\c. Les resonateurs la 2 / 3tio 3 presentent des caracteristiques prometteuses avec = 69 et qf = 17000 ghz mesure a 3ghz.
The effects of post-annealing on the crystal structure, microstructure, and microwave dielectric ... more The effects of post-annealing on the crystal structure, microstructure, and microwave dielectric properties for Ba(Co 0.7 Zn 0.3) 1/3 Nb 2/3 O 3 ceramics were investigated. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The microwave dielectric properties are measured at 6 GHz using a network analyzer. Ba 5 Nb 4 O 15 and/or Ba 8 (Co,Zn) 1 Nb 6 O 24 secondary phases were found on the surface according to sintering conditions due to volatilization of some Zn and Co elements. The experimental results show that the beneficial effect of the annealing steps to improved the microwave dielectric properties. Excellent microwave dielectric properties were achieved for the coarse-grained microstructures by a higher sintering temperature and with a shorter holding time followed by annealing steps at lower temperatures with a longer holding time. This improvement can be attributed to 1:2 cation ordering within the crystal, which is taking place during annealing process. The Ba(Co 0.7 Zn 0.3) 1/3 Nb 2/3 O 3 ceramic could be used successfully for realization of dielectric microwave resonators, since it has a high quality factor Q f value of 123,700 GHz, a high dielectric constant ε r value of 34.5 and a temperature coefficient of the resonant frequency τ f of 0 ppm/ ¥ C.
The polymer-mortar composites are often used as low-cost promising materials for preventing or re... more The polymer-mortar composites are often used as low-cost promising materials for preventing or repairing various reinforced concrete structures. The Thermal behavior of the building materials is relevant to any use of concrete or composite, especially in relation to structures where it is desirable to have low thermal conductivity, dimensional stability, high specific heat and little or no decrease of stiffness upon heating. Although much work has been done on the effect of admixture and the mechanical properties of concrete or composite, relatively little work has been done on the thermal conductivity. So, Thermal conductivity (), thermal resistance (R) and the surface coefficients of transmission (U) of polymer-mortar composites made up of mixtures of polyethylene terephthalate PET waste were measured. To determine the effect of the PET on the thermal conductivity of PET-mortar composites, PET was added as replacement for cement by decreasing the cement weights in the ratios of 2.5%, 5% and 7.5% by weight. The highest thermal conductivity of 1.45 W/mK was observed with the samples containing only plain cement. It decreased with the increase of PET as replacement for cement. The lowest value of thermal conductivity and the surface coefficient of transmission were obtained with the samples prepared with PET waste polymer at 7.5 % replacement of cement. The composites were also observed by DTA, MOP led to the positive identification of the products'. In this way, the results obtained highlight the beneficial effect of waste PET as thermal insulation in comparison with other insulation materials. In addition, the obtained PET-mortar composites would appear to be low-cost materials which would contribute to resolving some of the solid waste problems in addition to conserving energy.
Abstract: Ceramic porous MgTiO 3 materials have been prepared by classical solid-state route. The... more Abstract: Ceramic porous MgTiO 3 materials have been prepared by classical solid-state route. The sintering of ceramic samples with different LiF contents was studied using dilatometric, thermogravimetric, X-ray diffraction and microstructural analysis. The investigations results showed that the microstructure and porosity of samples were sensitive to LiF percents which generated a liquid phase eutectic (LiF-MgF 2 ), during the heating. Also, the Mg/Ti ratio took part in the structure formation of the ceramic. High grains size layers with cubic orientation were de tected at the surface of pellets sintered in air, at 900-1,000 °C, identified as Li 2 MgTiO 4 phase, regardless of LiF amount. At 1,100 °C, the Mg 2 TiO 4 compound, rich in Li, was found on the surface. The pores distribution in studied ceramics; depending on sintering temperature and LiF contents, has been obtained by Mercury porosimetry measurements. In these experimental conditions, dense ceramics could not be obtained, independently of the LiF amount.
International audienceLa méthode d’élaboration de poudre par flash combustion permet l’obtention ... more International audienceLa méthode d’élaboration de poudre par flash combustion permet l’obtention de poudres de taille nanométrique. Des quatre combustibles testés, ceux semblant mener le plus facilement à la formation de la phase recherchée (CaZrO3) sont la glycine et la ß-alanine. Ils conduisent à des poudres cristallisées après synthèse ainsi qu’à des éramiques relativement denses après frittage non optimisé
The purpose of this work is to decrease or eliminate porosities in electro-thermal explosion (ETE... more The purpose of this work is to decrease or eliminate porosities in electro-thermal explosion (ETE-VC) products with sintering additives. The Ti–C system has been synthesized for its advantages for refractory, abrasive and structural applications. We attempted to density TiC by using iron addition; this metal is introduced through a secondary reaction 3TiO3+Al. This mixture reacts exothermically ϪH298 = -1072.7 kJ and the heat is released according to by Fe addition 3TiO3+4Al+3C+xFe→3TiC+2Al2O3+xFe. .X-ray diffraction analysis indicated that intermetallic Fe3Al, TiC and Al2O3 are the main phases formed in the reinforced high-performance ceramic-matrix composites and the additions of Fe decreased the lattice parameter of TiC. Field emission scanning electron microscopy examinations showed that the addition of Fe decreased TiC particle size and changed their growth controlling mechanism. Also, Raman spectroscopy analysis showed that at higher Fe contents, oxygen dissolved in the TiC cr...
The present research is devoted to the optimization of the sintering schedule of Ba (Co0.7Zn0.3)1... more The present research is devoted to the optimization of the sintering schedule of Ba (Co0.7Zn0.3)1/3Nb2/3O3 (BCZN) dielectric ceramics for microwaves applications. A novel approach to the heat treatment of these ceramics based on the rapid-rate sintering (RRS) technique followed by a lower temperature annealing cycle has been developed. The relationships among the heat treatment process optimization, the structural, microstructural characteristics, and the microwave dielectric properties of the BCZN ceramics were investigated using X-ray diffraction, scanning electron microscopy, energy dispersion analysis, and vector network analysis. The RRS-technique shortens substantially the time required for the elaboration of these components in comparison with conventional sintering techniques and prevents simultaneously the formation of secondary phases as Ba5Nb4O15 and Ba8(Co, Zn) 1Nb6O24 on the surface of the ceramics. All of the sintered and annealed ceramics exhibit a high quality factor...
Matériaux pour l'électronique et dispositifs associés, 2015
Nombre de fonctions electroniques « passives » sont assurees par des composants realises par la t... more Nombre de fonctions electroniques « passives » sont assurees par des composants realises par la technologie ceramique : fonctions d’interconnexion, capacitives, resistives, inductives, de protection, capteurs (temperature, forces, deplacements, gaz…), etc. Les proprietes physiques des materiaux mis en œuvre, le plus souvent covalents, peuvent etre controlees par des substitutions dans la maille cristalline. La technologie ceramique permet egalement la realisation de microstructures inhomogenes et l’obtention de composants formes de plusieurs materiaux distincts tels les composants multicouches.
L'interet futur du marche des ceramiques pour resonateurs hyperfrequences porte sur de nouvea... more L'interet futur du marche des ceramiques pour resonateurs hyperfrequences porte sur de nouveaux materiaux de constante dielectrique e superieure a 50, caracterises par un bon facteur de qualite Q et un coefficient de stabilite en temperature τ f proche de 0 ppm/°C ou ajustable. Dans cette optique, nous nous sommes interesses aux proprietes dielectriques hyperfrequence de la phase perovskite metastable La 2/3 TiO 3 stabilisee par du nickel. Nous avons prepare des compositions (1-x)La 2/3 TiO 3 - xNiTiO 3 avec 0.01<x<0.15 par reaction en voie solide a partir des oxydes TiO 2 , La 2 O 3 , et NiO. Les temperatures de frittage, comprises entre 1320°C et 1380°C, ont ete determinees pour chaque composition par dilatometrie. La formation d'une phase isomorphe de La 2/3 TiO 3 a ete mise en evidence, en presence de phases secondaires, par diffraction des Rayons X et par observations microstructurales et analyses EDS realisees au microscope electronique a balayage. Les proprietes...
Magnesium titanate MgTiO3 is a well known compound for type I multilayer ceramic capacitors. Neve... more Magnesium titanate MgTiO3 is a well known compound for type I multilayer ceramic capacitors. Nevertheless the sintering temperature of the pure ilmenite MgTiO3 is around 1350°C. Such a high sintering temperature together with the high sensitivity of the dielectric material to reduction when heated in a low-oxygen containing atmosphere involve that MgTiO3-based MLCC include palladium-rich inner electrodes. The high level of variation of both the costs of Pd and Ag justifies researches leading to the use of cheaper metals such as silver or base metals such as nickel or copper. When using low-melting temperature metals (silver melts at 960°C and copper at 1085°C), the sintering temperature of the dielectric material has to be lowered. We report here on our investigations on the use of fluorine containing additives for the reducing of the sintering temperature of magnesium titanate, showing so the ability of this material to be sintered at temperatures much lower than 1000°C. Both diele...
Nanocomposites are wear resistant materials used in cutting tool applications. The materials are ... more Nanocomposites are wear resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo 2 C) 1-x (TiC) x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo 2 C-TiC was rapidly synthesised and simultaneously consolidated by Field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs as reinforcement of the CMNC's. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt.% SWCNTs from (Mo 2 C) 1-x (TiC) x , x= 0.2 which was sintered at 1700°C, 70 MPa for 10 min, M 0.8 T 0.2 / 1 Wt% SWCNTs exhibit a better density, highest hardness and a good ductility. Relative densification was achieved 99.5 % from the theoretical and a good mechanical properties like hardness and fracture toughness (K IC =5.6 Mpa m 1/2) are enhanced. The results were confirmed using Raman spectroscopy.
Nanocomposites are worn resistant materials used in cutting tool applications. The materials are ... more Nanocomposites are worn resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo2C)1-x–(TiC)x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo2C-TiC was rapidly synthesised and simultaneously consolidated by field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs was reinforcement of the NCMC’s. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and...
Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC... more Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC) ceramics matrix nanocomposites (CMNCs) tools were manufacturated by a field actived sparck plasma sintering processus (FASPS). The effects of cBN-TiC ratio, carbon nanotubes and optimisation of the sintering process on the microstructure, densification in addition mechanical and vibronic properties of NC-cBN-TiC nanocomposites were studied. The results showed that for the nanocomposite cBN-TiC vol. ratio of 8:2 with 0.1 wt% NC, it was found that microhardness incresses significantly with addition of carbon nanotubes exhibited the highest microhardness and fracture toughness. After sintering of the samples at 1800 °C, 10 mn, 75 MPa of cBN–TiC1-x, x=0.8 with and without addition of 0.1 wt% NC were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction. The samples exhibited a dense polycrystalline structure. From the resonant Raman scattering we can...
Biomedical Journal of Scientific & Technical Research, 2019
Nanocomposite Ti 50 wt% Nb with and without reinforcement of carbon nanotubes were successfully f... more Nanocomposite Ti 50 wt% Nb with and without reinforcement of carbon nanotubes were successfully fabricated by ball milling of Ti, Nb and SWCNTs nano powder mixture followed by field activated spark plasma sintering process (FASPS) for biomedical application, superconductivity and magnetism in the ITER Project. The use of brittle Ti powder, instead of ductile elemental powder, led to significant increment in the yield of mechanically alloyed powder. The powder consisted of homogeneously distributed nano-sized Ti/Nb particles together with micron-sized pure Nb particles. Sintering of the powders under low temperature and pressure conditions (1273 K, 1473 K and P=50 MPA) resulted in the fine-grained heterogeneous microstructure consisting of α and β phases. On the other hand, sintering at higher temperatures (1473 K) resulted in a relatively coarsegrained chemically homogeneous microstructure with almost complete phase. Coarse-grained homogeneous β TiNb alloy exhibited higher average hardness as compared to that of heterogeneous fine-grained microstructures. An attempt has been made to illustrate the correlation between the microstructural characteristics and mechanical properties of the sintered Ti50Nb compacts. To studies and to develop the influence of CNTs on the behavior of the nanocomposite TiNb/CNTs and the welding joint interface between TA6V and nanocomposite by Sparck plasma sintering. At last, the continuation of the work has been discussed and prepared, planning dynamic flexion tests to measure the TiNb, TiNb/CNTs, TiNb/CNTs,/TA6V fatigue limit and developing a computer processing chain in order to customize prostheses respecting patients' morphology. The fluid enhanced lubrification of the prosthesis articulation is currently also in preparation. the practice of joint replacement in both the knee and the hip to
International Journal of Applied Ceramic Technology, 2019
This paper is focusing basically on the ceramic technology, of which several methods for the synt... more This paper is focusing basically on the ceramic technology, of which several methods for the synthesis of MgAl 2 O 4 have been investigated. The synthesis conditions regarding the powders cleanliness, microstructure and sintering parameters of MgAl 2 O 4 were studied. MgAl 2 O 4 powder was synthesized via conventional solid-state route using different milling process: vertical attrition milling, WAB as a high-energy horizontal attrition milling and Pulverisette as a planetary ball miller, and via solution combustion route using Urea, Glycine and a mixture of Urea/Glycine. Urea and Glycine was used as fuel. The white powders was obtained for all solid-state routes and for Urea-combustion technique. The black and gray powders were obtained in the case of combustion technique, respectively, by using a fuel of Glycine and Glycine/Urea mixture. The obtained powders and pellets were characterized by XRD, SEM, and Dilatometry. The results show that, among all the solid-state route processes, wet attrition milling gives the better and clean spinel phase. The WAB milling and Pulverisette miller introduce a contamination by some yttria-stabilized zirconia balls in the corresponding powder. Further, the flash combustion technique permit to have nanoparticles with a dense spinel phase of MgAl 2 O 4 and with lower sintering temperature in less time and with no calcination step.
Environmental Engineering and Management Journal, 2017
The main objective of this study was to investigate the potential utilization of polyethylene ter... more The main objective of this study was to investigate the potential utilization of polyethylene terephthalate PET waste in cementitious matrix, as substituent to cement, to develop lightweight construction materials and for preventing chemical attacks or repairing various reinforced concrete structures. Composites containing different amounts of PET particles, as partial replacement to cement by weight, were characterized by destructive and non-destructive testing. So, the thermal conductivity, ultrasonic pulse velocity (UPV) and sorptivity coefficients of composite made up of mixtures of PET polymer were measured; the adverse environmental conditions are simulated by using various acid solutions. The corrosion process was monitored by measuring the mass loss and compressive strength for different periods. The experimental investigation revealed that the addition of PET particles reduces the UPV; furthermore, thermal conductivity and sorptivity of the composites have been decreased. So, the decrease of the sorptivity-value is favorable to the durability of the specimen structures. On behalf of the resistance to aggressive environments, it was found that the course of action of acid attack is dependent on the type of acid and solubility of the calcium salt formed. The presence of PET was found to lower the detrimental effect of acids on composite. Scanning electron microscope (SEM), X-ray diffraction and FT-IR analyses were used to better understand the cement hydration products of the deteriorated mortars. In this way, the obtained PET-mortar composites would appear to be low-cost materials which would contribute to resolving some of the solid waste problems in addition to conserving energy.
Le materiau (zr,sn)tio 4 est utilise pour la realisation de resonateurs hyperfrequences. L'ob... more Le materiau (zr,sn)tio 4 est utilise pour la realisation de resonateurs hyperfrequences. L'obtention de facteurs de merite qf superieurs ou egaux a 50000 ghz pour des frequences de resonance inferieures a 5 ghz, ainsi que le broyage des matieres premieres, poudres d'oxydes tio 2, zro 2 sno 2, la 2o 3 et nio, par un procede d'attrition utilisant un broyeur industriel dyno-mill sont mal maitrises. L'etude menee focalise alors sur la connaissance de l'etat de dispersion des barbotines, l'optimisation du broyage et des facteurs de merite des resonateurs et la comprehension des relations entre microstructures et proprietes dielectriques. Enfin le marche evoluant vers des materiaux avec des constantes dielectriques plus grandes, une etude sur des compositions la 2 / 3tio 3 stabilise au nickel a ete menee. L'etat de dispersion des barbotines aqueuses de poudres d'oxydes, en fonction de la charge en solide et du ph, a ete caracterise par rheologie et mesure du potentiel zeta. Il en resulte que les barbotines de charge en solide de 50% en masse sont stables, defloculees pour des ph superieurs a 10,5. Dans ces conditions les barbotines presentent des valeurs de viscosite suffisamment faibles pour permettre le broyage par attrition avec le dyno-mill. L'influence des autres etapes technologiques, et notamment le frittage, sur les proprietes dielectriques a ete etudiee. Des recuits realises a 1250\\c apres frittage permettent d'ameliorer les facteurs de qualite des resonateurs d'environ 20%. Les observations microstructurales realisees par diffraction des rx, meb, eds et analyses d'images ont permis de montrer que les ceramiques sont polyphasees et que certaines phases diffusent vers la surface lors du recuit. Les resonateurs zst synthetises presentent alors de tres bonnes et reproductibles caracteristiques dielectriques : = 37,5,qf = 50000 ghz mesure a 4 ghz, f proche 0 ppm/\\c. Les resonateurs la 2 / 3tio 3 presentent des caracteristiques prometteuses avec = 69 et qf = 17000 ghz mesure a 3ghz.
The effects of post-annealing on the crystal structure, microstructure, and microwave dielectric ... more The effects of post-annealing on the crystal structure, microstructure, and microwave dielectric properties for Ba(Co 0.7 Zn 0.3) 1/3 Nb 2/3 O 3 ceramics were investigated. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The microwave dielectric properties are measured at 6 GHz using a network analyzer. Ba 5 Nb 4 O 15 and/or Ba 8 (Co,Zn) 1 Nb 6 O 24 secondary phases were found on the surface according to sintering conditions due to volatilization of some Zn and Co elements. The experimental results show that the beneficial effect of the annealing steps to improved the microwave dielectric properties. Excellent microwave dielectric properties were achieved for the coarse-grained microstructures by a higher sintering temperature and with a shorter holding time followed by annealing steps at lower temperatures with a longer holding time. This improvement can be attributed to 1:2 cation ordering within the crystal, which is taking place during annealing process. The Ba(Co 0.7 Zn 0.3) 1/3 Nb 2/3 O 3 ceramic could be used successfully for realization of dielectric microwave resonators, since it has a high quality factor Q f value of 123,700 GHz, a high dielectric constant ε r value of 34.5 and a temperature coefficient of the resonant frequency τ f of 0 ppm/ ¥ C.
The polymer-mortar composites are often used as low-cost promising materials for preventing or re... more The polymer-mortar composites are often used as low-cost promising materials for preventing or repairing various reinforced concrete structures. The Thermal behavior of the building materials is relevant to any use of concrete or composite, especially in relation to structures where it is desirable to have low thermal conductivity, dimensional stability, high specific heat and little or no decrease of stiffness upon heating. Although much work has been done on the effect of admixture and the mechanical properties of concrete or composite, relatively little work has been done on the thermal conductivity. So, Thermal conductivity (), thermal resistance (R) and the surface coefficients of transmission (U) of polymer-mortar composites made up of mixtures of polyethylene terephthalate PET waste were measured. To determine the effect of the PET on the thermal conductivity of PET-mortar composites, PET was added as replacement for cement by decreasing the cement weights in the ratios of 2.5%, 5% and 7.5% by weight. The highest thermal conductivity of 1.45 W/mK was observed with the samples containing only plain cement. It decreased with the increase of PET as replacement for cement. The lowest value of thermal conductivity and the surface coefficient of transmission were obtained with the samples prepared with PET waste polymer at 7.5 % replacement of cement. The composites were also observed by DTA, MOP led to the positive identification of the products'. In this way, the results obtained highlight the beneficial effect of waste PET as thermal insulation in comparison with other insulation materials. In addition, the obtained PET-mortar composites would appear to be low-cost materials which would contribute to resolving some of the solid waste problems in addition to conserving energy.
Abstract: Ceramic porous MgTiO 3 materials have been prepared by classical solid-state route. The... more Abstract: Ceramic porous MgTiO 3 materials have been prepared by classical solid-state route. The sintering of ceramic samples with different LiF contents was studied using dilatometric, thermogravimetric, X-ray diffraction and microstructural analysis. The investigations results showed that the microstructure and porosity of samples were sensitive to LiF percents which generated a liquid phase eutectic (LiF-MgF 2 ), during the heating. Also, the Mg/Ti ratio took part in the structure formation of the ceramic. High grains size layers with cubic orientation were de tected at the surface of pellets sintered in air, at 900-1,000 °C, identified as Li 2 MgTiO 4 phase, regardless of LiF amount. At 1,100 °C, the Mg 2 TiO 4 compound, rich in Li, was found on the surface. The pores distribution in studied ceramics; depending on sintering temperature and LiF contents, has been obtained by Mercury porosimetry measurements. In these experimental conditions, dense ceramics could not be obtained, independently of the LiF amount.
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