Abstract: A system for gas separation has a mechanically stable metallic substrate layer having a pair of opposite faces and formed throughout with open pores. Respective functional layers laminated on each of the faces are composed of TiO2 or ZrO2. These functional layers are formed throughout with pores having an average pore diameter of less than 1 nm.

Abstract: The invention relates to a method for producing a device for gas separation, said device comprising a layer system wherein a functional layer consisting of TiO2 and/or ZrO2 having an average pore diameter of less than 1 nm is applied to at least one side of a carrier layer that is porous throughout. Said carrier layer is preferably between 100 ?m and 1 mm thick and comprises continuous pores with an average pore diameter in the ?m range. The functional layer which is applied directly or by means of at least one intermediate layer comprises continuous pores with an average pore diameter of less than 1 nm, especially less than 0.8 nm. The functional layer can advantageously be embodied as a graduated layer. The invention is especially characterised by the symmetrical structure of the device, in which functional layers are applied to both sides of the carrier layer, optionally by means of respectively at least one intermediate layer.

Abstract: The invention relates to a method for producing a tight crystalline mullite layer on a metallic and/or ceramic substrate by using the plasma spraying technique. To this end, a sol containing mullite precursors with a proportion of 2 to 25% by weight with regard to the oxides (3 Al2O3/2 SiO2) is used as a spraying additive. This method is carried out under atmospheric conditions, and the sol is injected with a focussed jet and with an overpressure of at least one I bar into the plasma flame. An additional compacting of the layer can be advantageously effected by repeatedly passing over the layer with the plasma flame. The method is particularly suited for applying a gas-tight crystalline mullite layer to a steel substrate.