Abstract: A method of making imprints on the walls of portions of a tube obtained by the continuous molding of a ceramics-based paste and the cutting up of the tube, wherein immediately after the tube portions have been molded and are still deformable, they are placed on means parallel with the axis of the tube portions for rotating them around their axes of revolution, means are applied to the rotary means for exerting a pressure on at least a portion of the tubes so that such portions are clamped between the rotary means and the pressure-exerting means, the pressure-exerting means or the rotary means are provided with at least one imprint-making tool, the or each tool having a main direction which does not coincide with the direction of the axes of revolution of the tube portions, and means are applied to create a second relative movement between the tube portion and the or each tool, so that there is substantially no sliding between the tube portion and the or each tool.

Abstract: The invention relates to a support for a ceramic porous barrier of the kind used for obtaining a concentration of uranium 235 in uranium hexafluoride by ultrafiltration. The support is formed by superposing a number of layers in the form of pastes, the particle size being homogeneous and constant in each layer and decreasing from the outer towards the inner layers. The pastes are prepared from powdered materials such as metals, oxides, silicates, borides, nitrides and halides to which mineral binders are added. The pastes are simultaneously extruded or co-extruded after which the resulting support is baked.