Structure and Properties of Porous Ti 3 AlC 2 -Doped Al 2 O 3 Composites Obtained by Slip Casting Method for Membrane Application.

In the present work, porous composites were fabricated from pure Al 2 O 3 and mixed Ti 3 AlC 2 /Al 2 O 3 powder by slip casting and sintering. The effect of sintering temperature and different composition ratio on microstructure, phase composition, porosity and gas permeation flux of the fabricated materials was investigated. The microstructure and phase composition of the samples were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The gas permeation experiments were performed using pure hydrogen at 0.1-0.9 MPa pressure. It is shown that a decrease in sintering temperature from 1500 to 1350 °C results in an increase in hydrogen permeation flux of the alumina from 5 to 25 mol/(m 2 × s), which is due to higher pore size and overall porosity of the samples. Sintering of Ti 3 AlC 2 /Al 2 O 3 powder mixtures leads to the formation of Al 2 O 3 , Al 2 TiO 5 and TiO 2 phases as a result of oxidation of the Ti 3 AlC 2 phase, resulting in an increased pore size in the composites compared with pure alumina. The open porosity of composites increases from 3.4 to 40% with an increasing Ti 3 AlC 2 /Al 2 O 3 ratio from 1/10 to 1/2, respectively. The composites with the highest porosity (40%) had a maximum permeation flux of 200 mol/(m 2 × s). The changes in the bending strength of the alumina and composite samples, depending on the microstructure and porosity, were also discussed. The investigated composites are considered promising materials for hydrogen separation membrane supports.