PURPOSE: To make a porous inorganic composite semipermeable membrane without cracks and stable at high temperatures by selecting a first oxide phase and a second oxide whose diffusion both to the surface of and to the grain boundaries in the first oxide phase is suppressed and has low solubility in the first oxide phase.
CONSTITUTION: A support and a separating layer which has pores with an average diameter less than 1 μm and which comprises at least two refractory metal oxides are prepared. The separating layer is composed of grains of a first oxide phase 1 (e.g. Al2O3) and grains of at least one type of a second oxide 2 (e.g. ZrO2). The 2nd oxide grain 2 is dispersed over and chemically bonded to the first oxide phase 1, so as to constitute at least a portion of the free surface of the 1st phase grains 1 and at least a portion of the grain boundaries between the 1st phase grains 1. By selection of the first oxide phase 1 and the second oxide 2, the diffusion of the second oxide is prevented on the surface of the first oxide phase 1 and the 1st phase grain boundaries and the second oxide has low solubility in the first oxide phase. The volume of the second oxide 2 is regulated in the range of 0.1% to 25% of the volume of the first oxide phase 1.
ROBERUTO IEE ERU UURUHORUN
IBUUSHIEN RIN
KURAASU KEIZERU
ANTONII IEE BURUUFURAAFU
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