GB1163808A - Manufacture of Sintered Metal Articles - Google Patents

Abstract

1,163,808. Moulding metal powder compacts. HENRY WIGGIN & CO. Ltd. 29 Aug., 1968 [7 Sept., 1967], No. 41007/67. Heading B5A. [Also in Division C7] In the moulding by isostatic compression of a metal powder article which is cored with a powder of different composition, a close-fitting polyethylene bag 4 is suspended within a mild steel container 1, a copper-nickel tube 7 which is spaced by fins 8 is then lowered into the bag 4 on to a bottom layer of nickel powder, and raised therefrom as iron powder 11 is deposited therewithin and nickel powder 6 therearound; the level of the latter being maintained higher than that of the former, providing a top covering layer over the core when tube 7 is withdrawn. The container 1 is vibrated during the filling. The bottom and upper covering layers may be omitted. The bag 4 is closed and transferred within the container 1, which is provided with holes 2 in the base thereof, to a pressure vessel where a compact is formed at 30,000 p.s.i. The bag 4 may remain or be removed prior to sintering by heating to 1100‹ C. at a rate of temperature increase less than 100‹ C. per hour between 400‹ and 900‹ C., and less than 150‹ C. per hour thereafter. The sintered compact is machined and extruded or, alternatively, may be hotrolled and drawn in stages, with intermediate annealing, to 5 mm. nickel coated wire. Tubular compacts may be made by employing a solid removable core within the tube 7 when this is also provided with internal core engaging fins. A plurality of concentric filling tubes 7 may be employed with powders of different compositions fed to the spaces therebetween. The bag 4 and tube 7 may be cylindrical, square or rectangular.