Mineralogical and physicochemical investigation of Mg-smectite from Jbel Ghassoul, Marroco

International audience'Ghassoul' clay is a Mg-rich clay from Morocco which is of great industrial use and interest, but its characterization is still incomplete. The purpose of this study was to provide further details regarding the structure and characteristics of this important commercial clay mineral. Mineralogical and physicochemical characterizations of the raw form of 'Ghassoul' clay from Jbel Ghassoul in Morocco, and of its 800°C and that quartz was transformed to cristobalite when the temperature exceeded 1100°C. These transformations were irreversible. The specific surface area and cation exchange capacity (CEC) of the 'Ghassoul' clay are 133 m2/g and 75 meq/100 g, respectively. The main exchangeable cation is Mg2+ (53 meq/100 g

Calcium aluminate cement tapes - Part II: Physical properties

International audienceTape casting is a process often used for the preparation of microelectronics substrates. The present work is a continuation of the first part where we have discussed the structural and microstructural characteristics of calcium aluminate cement tape. Indeed, in this second part, we focus on the physical properties of these tapes such as electrical, thermal, mechanical characterizations and surface roughness. We studied in particular how these physical properties vary according to the setting environment (water, air at 50% relative humidity or air saturated in humidity), setting time (1 day, 4 days or 1 month) and setting temperature (20 °C or 70 °C in the case of water setting environment). A Heat treatment on the consolidated tape was made essentially to decrease the dielectric constant. Following our results and comparing the physical properties with those of substrates commonly used in microelectronics, in particular alumina substrates, our films can be potentially used as microelectronics substrate

Role of dispersant and humidity on the setting of millimetric films of aluminous cement prepared by tape casting

An aluminous cement (Secar 71 from Lafarge) has been used for preparing millimetre thick films by tape casting. Slurry preparation is described. The effect of several dispersants has been studied. The optimum dispersion, associated with the minimum viscosity, is obtained with minimal amounts of dispersant in the case of acetic and propionic acids. Indeed, the corresponding quantities of dispersant are less than 0.5% by weight relative to cement. In addition to its dispersive role, acetic acid plays a role in the setting. It has a retarding effect below 1% by weight relative to the mass of cement and from this amount, it plays an accelerating role on setting. Tapes prepared with cement, water, acetic acid, PEG 300 have been left to set in different environments at 20 ◦C (50% or 95% relative humidity, water). The formation of aluminous calcium hydrates is most important when setting is done in water. Lastly, the advantage of setting in water is also discussed with respect to the elimination of the different organic products that have been used for tape casting

Calcium aluminate cement tapes - Part I: Structural and microstructural characterizations

International audienceThis present paper concerns the structural and microstructural characterization of 1 mm thick calcium aluminate cement tapes prepared by tape casting. A study of the effect of environment, time and the consolidation temperature on the structural properties and microstructure has been undertaken. Consolidation environments studied are air, water and an environment saturated in humidity for storage durations of 1, 4 or 30 days at a temperature of 20 or 70 °C. The structural characterization was carried out using XRD. The microstructural characterization was carried out through the distribution of pore volume by mercury porosimetry measurements and SEM micrographs. The effects of the various consolidation parameters were compared and discussed. The tape consolidated for 30 days in water at 70 °C has the most advanced hydration with the formation of stable hydrates. This is evidenced by the reduction of the inter-granular pore size and the microstructure densification

Effect of temperature and clay addition on the thermal behavior of phosphate sludge

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Porous ceramic from Moroccan natural phosphate and raw clay for microfiltration applications

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Antimicrobial ceramic foam composite air filter prepared from Moroccan red clay, phosphate sludge waste and biopolymer

The COVID-19 pandemic has highlighted the importance of air sterilization and disinfection. Besides the regular cleaning and disinfection of surfaces it is at least as important to reduce the number of airborne microorganisms as they are known to play an important role in the spreading of different infections. Herein, we report a facile preparation of a porous air filter ceramic composite material, suitable for the effectively eliminating airborne microorganisms. The antimicrobial activity of the ceramic foam could be attributed to a thin chitosan biopolymer layer immobilized on the ceramic surface. Furthermore, as the ceramic foam was prepared on phosphate sludge waste and Moroccan red clay basis, this research opens new routes towards the valorization of solid industrial or mining wastes or other yet unused abundant materials, as well