GB818312A - Improvements in or relating to metal coatings - Google Patents

Abstract

818,312. Powder metallurgy. UNITED KINGDOM ATOMIC ENERGY AUTHORITY, Feb. 24, 1958 [March 22, 1957]. No. 9570/57. Class 82(1) [Also in Groups XXII and XL(a)] Articles, particularly nuclear fuel elements of U, Th, or their oxides or carbides, are coated with metal, e.g. Be, by compacting the powdered metal around the article enclosing the whole in a die shaped to fit the assemblage and of material (e.g. mild steel) deformable at the forging temperature, and forging at a temperature below the melting point of the powdered metal and such that the latter is consolidated without liquefying (i.e. 1000‹- 1200‹C in the case of Be). The powdersurrounded article may be enclosed in a deformable sheath (4) prior to forging in the deformable die. In an example, Be powder is cold compacted to form linings 2, 5 on mild steel trays 1, 4 between which is enclosed a core 3 of sintered UO 2 . The trays are welded together at 6 and evacuated, placed in a close fitting mild steel die 7 which is covered by a mild steel die plate 8,-both dies being graphitized on their faces,-and the whole confined in a non-deformable sleeve 12 and between the platens 9, 10 of a hydraulic press. A pressure of about 2000 p.s.i. is applied by the press, the temperature of the assembly having first been raised to 1100‹C. Under these conditions the trays and dies are plastic. On cooling and removing the assembly, the sheath 4 of the latter is removed with nitric acid. In a variation of the above, the trays 1, 4 may be thicker (e.g. ¥ inch) and the dies 7, 8 be dispensed with.