Preparation Of Ceramic Membranes Research Articles

CVD of solid oxides in porous media for ceramic membrane preparation or modification. Explicit solutions for deposition characteristics

A theoretical analysis of modified chemical vapor deposition (MCVD) of solid oxides in porous media for ceramic membrane preparation and/or modification is presented in this paper. Semi-analytical solutions have been obtained to describe the evolution of solid deposit profiles inside porous substrates, using a phenomenological model that takes into account intrapore precursor diffusion, chemical reaction and pore geometry change. Explicit equations have been derived which correlate the three main deposition characteristics, deposit location, deposit zone thickness and pore closure time to the CVD experimental parameters and substrate pore structure. Such explicit equations provide better insight into this unique CVD process for advanced materials synthesis and are very useful in practical applications. A comparison of the semi-analytical solutions with a numerical solution based on the finite element method is also presented. The semi-analytical solutions are in good agreement with the numerical solutions, especially under the conditions used for ceramic membrane preparation and/or modification.

Modelling and analysis of CVD processes for ceramic membrane preparation

A mathematical model is presented that describes the modified chemical vapour deposition (CVD) process (which takes place in advance of the electrochemical vapour deposition (EVD) process) to deposit ZrO 2 inside porous media for the preparation and modification of ceramic membranes. The isobaric model takes into account intrapore Knudsen diffusion of ZrCl 4 and H 2O, which enter the membrane from opposite sides, and Langmuir-Hinshelwood reaction of the solid product ZrO 2 on the internal pore wall. The processes occurring in one single pore are investigated, and the change in pore geometry during deposition is taken into account. Based upon this model, the deposition profile is studied. The model fits reasonably well with experimental results.

Preparation of Heat Resistant Microporous Ceramic Membranes for Selective Gas Permeation

Microporous membranes of hexaaluminates (Ba- and La-Al 2 O 3 ) showed heat resistance much higher than that of the conventional Al 2 O 3 membrane. Although the Al 2 O 3 membrane cracked by the heat treatment above 1000 o C due to γ-α transformation. Ba- and La-Al 2 O 3 membranes retained crack-free microstructure and exhibited excellent selective gas permeation after calcination up to 1000 o C

A program for calculating the observables for single-particle-inclusive production reactions

In this study, a phase-inversion casting method with the self-designed forming mold and preparation route was proposed for preparation of tubular ceramic membranes. Thermal and sintering behaviors of as-prepared green tubular membranes were investigated. The results show that the significant weight loss occurs between 400 and 600 °C and three shrinkage stages appear in sintering process. Pore size distribution, image analysis, porosity, mechanical strength and gas flux were also studied to characterize the fabricated ceramic membranes. SEM images illustrate that the tubular membrane has a nearly homogeneous microstructure with good pore interconnect and uniform pore dispersion. With increasing of sintering temperature from 1500 to 1600 °C, the porosity decreases from 51.2 to 45.1% and the average pore size from 0.79 to 0.71 μm, while the flexural strength increases from 22.2 to 41.5 MPa. All these properties clearly suggest the practicability of the phase-inversion casting process to prepare tubular ceramic membranes.

Review on Development of Ceramic Membrane From Sol-Gel Route: Parameters Affecting Characteristics of the Membrane

The importance of laboratory scale ceramic membrane preparation using sol-gel technique with pore sizes in the range of 1-10nm is reviewed. Parameters affecting the characteristics of membrane during membrane development are highlighted and discussed in detail. Experimental results from literatures have shown that the correct amount of acid, water, PVA, appropriate membrane thickness, proper control of drying rate, and appropriate temperature profile selection during sintering process are necessary in order to acquire sufficient strength and reduce the formation of crack in the membrane. The different temperature setting during sintering process also influences the size of pore formed.Key Words: Sol-Gel, Inorganic Membrane, Ceramic Membrane, Gas Permeation, Sintering, Sol Properties, Membrane Morphologies, Pore Size Distribution.