Вплив дифузії бору на утворення силіциду титану

Метод вторинно-іонної мас-спектрометрії (ВІМС) був використаний для дослідження дифузії бору в шарах силіциду титану за кількох умов відпалювання та температури. Експериментальні профілі були змодельовані за допомогою моделі, заснованої на відомих законах Фіка та ефекті, що супроводжує дифузію бору під час силіцидації, як сегрегація та кластеризація. Порівняння результатів моделювання з літературними даними в однакових умовах відпалювання вказують на хорошу відповідність із результатами інших авторів. Це пояснює, що дифузія бору в силіциді титану залежить від сегрегації, кластеризації та перевищує розчинність твердої речовини. Моделювання базується на чисельному методі кінцевих різниць.Secondary ion mass spectrometry (SIMS) has been used to investigate Boron diffusion in Titanium silicide layers for several annealing conditions of duration and temperature. Experimental profiles were simulated using a model based on the famous Fick’s laws and the effect accompanying boron diffusion during silicidation like segregation and clustering. The comparison between simulation results and those of the literature in the same annealing conditions shows a good agreement between our results and those of other works. This explains that boron diffusion in titanium silicide depends on segregation, clustering and the solid solubility exceeds. The simulation is based on the finite difference numerical method. High agreement between simulation and experiment is shown

Preparation and characterization of ZnO microfiltration membrane and its support using kaolin (DD3) and CaCO3

Abstract The objective of the present paper was to prepare a ceramic support with membrane. Tubular ceramic supports prepared from kaolin (DD3) and calcium carbonate with 6 and 10 mm inner and outer diameters, respectively, were extruded and sintered at 1200 °C. It has been found that sintered supports had interesting characteristics: average pore size of about 5µm, porosity of about 50%, and monomodal pore size distribution. This support was used to be substrate for a membrane layer of microfiltration. This membrane layer was elaborated from zinc oxide, using slip casting technique. The specimens were subsequently sintered at 1000 °C. The microstructure and porosity as well as the permeability have also been studied. It has been found that the average pore size was about 1.2µm, the layer thickness was ~33µm, and the water permeability measured was about 880 L.h-1.m-2.bar-1

Elaboration of porous gehlenite and anorthite based ceramics using low price raw materials

Abstract Porous ceramics of good quality cost a lot in the world market, which has limited their use in developing countries. This is why this work was mainly devoted to prepare low-cost and good quality ceramics, using kaolin (DD2 type) and calcite (CaCO3) available in abundance in Algeria. Based on previous results, 28 wt% CaCO3 ceramic was selected. The presence of CaCO3 favors to achieve porous samples characterized by a high percentage of porosity due to the CO2 release and CaO formation during its calcination at about 700 °C. The choice of these raw materials is based on their natural abundance (low price). It has been found that the samples had interesting characteristics: average pore size between 2.87 and 6.50 μm and porosity between 53 and 57%. It has also been found that the manufactured membrane supports are mainly constituted of gehlenite and anorthite phases. Moreover, the pore size distribution was mono-modal type. The surface and cross-section morphologies observed through a scanning electron microscope were also homogeneous and do not present any possible macro-defects (cracks, etc.)

Sintering of anorthite based ceramics prepared from kaolin DD2 and calcite

Abstract In this work, the preparation of anorthite based ceramics using a modified milling system and 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide extracted from CaCO3 is shown. The choice of these raw materials was dictated by their natural abundance. Previous studies have shown that a simple and vibratory multidirectional milling system using a bimodal distribution of highly resistant ceramics can be successfully used for obtaining fine powders. The prepared samples were sintered at different temperatures ranging between 800 and 1100 °C. It has been found that the relative density of samples sintered at 900 °C for 1 h with a heating rate of 5 °C/min was about 96% of the theoretical density of anorthite (2.75 g/cm3). Finally, the prepared samples were also characterized by scanning electron microscopy, X-ray diffraction and Raman spectroscopy

Mechanical properties of anorthite based ceramics prepared from kaolin DD2 and calcite

Abstract Good quality ceramics costs a lot that has limited their use in developing countries. This work was devoted to prepare low-cost and good quality anorthite based ceramics. The proposed composition was 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide (CaO). The choice of these raw materials was dictated by their natural abundance coupled with a modified milling system, as another interesting advantage. Previous studies have shown that a simple vibratory multidirectional milling system using bimodal distribution of highly resistant ceramic milling elements has been successfully applied for obtaining fine powders. The influence of the relatively lower sintering temperature, ranging from 800 to 1100 °C, on the porosity and the average pore size (APS) have been investigated. The APS and the porosity values of samples sintered at 950 °C were about 1 μm and 4%, respectively. The best Vickers microhardness and 3-point bending strength values for these sintered samples, using this proposed milling system, were 7.1 GPa and 203 MPa, respectively. Finally, the crystalline phase evolution during heat treatment was investigated by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques