| 摘要 |
908,480. Anodized tubular bodies. COMMISSARIAT A L'ENERGIE ATOMIQUE. March 27, 1961 [March 30, 1960], No. 11139/61. Addition to 856,230. Class 41. [Also in Group XXII] In a method of producing a thin porous element with stiffening ribs on one face, comprising mechanically working a thin metal sheet to form ribs on one face, subjecting the other face to an oxidizing treatment to transform into oxide the whole thickness of the metal in the regions between the ribs, but leaving the ribs unoxidized, the element is given a tubular shape before the oxidizing treatment. The resulting porous tubular element is intended more particularly for the separation of isotopes by gaseous diffusion and may be made of a sheet from 60 to 300 microns thick of a metal or alloy which forms a strongly adhering oxide layer such as aluminium, magnesium, chromium, nickel, tantalum, titanium, vanadium, zirconium, hafnium and alloys thereof. The sheet is formed into a tube 1 of circular or polygonal crosssection placed over a mandrel 5 while the ribs 3 are formed as by rolls 6 with teeth 4, Fig. 3, or by dies 7, Fig. 5. If the resulting ribbed element is of polygonal section, it is made round by applying an internal fluid pressure of 2 or 3 kgs. per sq. cm. The oxidizing of the tube is preferably carried out by anodic treatment, the ends of the tube 1 being connected to a tank and electrolyte 11 circulated through it while an electric current is passed between the tube and a central rod 10. In an example, the tube is of an alloy of aluminium and magnesium containing 3% magnesium, is 15 mm. internal diameter and has a wall thickness of 0.04 mm. between the ribs which project 0.11 mm. The electrolyte is a 7% aqueous solution of oxalic acid at 30‹ C., the rod 10 is of molybdenum and the current density 1.2 amps. per sq. decimetre of tube surface. 2.9 ampere hours was required to oxidize the required thickness of 0.04 mm. |
