Improved method of treating cast copper

782,388. Coating with metals. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. April 27, 1956 [May 6, 1955], No. 13217/55. Class 82(2) [Also in Group XL(a)] The grain boundary regions of copper cast under vacuum are sealed by coating with a layer of copper-silver eutectic alloy and then heating in a reducing atmosphere to cause infiltration of the alloy into the boundary regions. Preferably the alloy is applied by spraying and the heating is in hydrogen to between 800 and 900‹C. The invention is described as applied to the hollow vacuum-cast copper anode 9 of an X-ray tube with refractory metal target 8a. After machining to size the outer surface of the anode is shot-blasted (the disc 8a being protected by e.g. neoprene), the anode boiled in water to loosen and remove grit and degreased with trichlorethylene. A layer of about 0.005 inch of copper-silver eutectic alloy is sprayed on (11) and the anode heated in hydrogen to between 800- 900‹C. where it is held for 1 minute. A layer of nickel (12) may have previously been electroplated on to the hollow portion of the copper anode and diffused in by heating.