| 摘要 |
<p>The invention relates to porous membranes made of sintered silica or refractory metal oxides, e.g. alumina, titania, zirconia, tungsten oxide, etc., and to a process for their formation. The membranes are formed by dispersing a powder of the metal oxide or silica in an organic polymer. The relative amount of silica or metal oxide to polymer is such that, after the polymer has been carbonized in a subsequent step, there is a stoichiometrical excess of the oxide to carbon. The solution is then shaped to form a desired thin membrane, and the polymer is then carbonized by heating it in a non-oxidizing atmosphere. The resulting oxide/carbon product is heated to a temperature at which (a) the carbon reacts with the oxide to form a volatile sub-oxide and carbon monoxide and (b) the remaining (unreacted) oxide particles sinter together. The heating is carried out in a non-oxiding atmosphere containing either no nitrogen whatsoever, or an amount of nitrogen less than that which results in the formation of a non-porous product. The sintered membranes can be used, for example, as filters and catalyst supports and have good strength and controlled porosity.</p> |
