Improvements relating to powder metallurgical processes

Abstract

Abstract 611,466. Making turbine blades; powder metallurgy. GENERAL ELECTRIC CO., Ltd., and JENKINS, I. May 1, 1946, No. 13159. [Classes 83 (ii) and 83 (iv)] In a method of forming ducts, holes or voids in a body of sintered metal powder, particularly cooling ducts of very fine bore in gas-turbine blades, suitably shaped formers at least partly metallic, are introduced into the powder before the final sintering process, the formers being composed of, or convertible into a material fusible at a temperature lower than the final sintering temperature. In particular applications, pure tin wires of 0.015 in. diameter and 4 in. long were pressed in molybdenum in a mould 4 in. by # in. under 35 tons per sq. in. pressure to produce a bar approximately <SP>5</SP>/ 16 in. thick, the bar then being heated in a hydrogen atmosphere to above the fusing point of the tin. Cadmium wires of a similar size were pressed into a compacted bar of an alloy of mainly chromium and cobalt, the compact being held at the temperature of the boiling point of cadmium for some hours in a hydrogen atmosphere before the final sintering process. The choice of former material is governed by the conditions of heat treatment and composition of the main body, cadmium being stated to be suitable when heat treatment takes place in an oxidising atmosphere. The former may be of complicated shape and either solid or hollow. In addition to tin and cadmium, zinc or indium may be used for the former. In the manufacture of ducted gas-turbine blades in accordance with the invention, a number of wires of, for example, cadmium would be disposed in the powder body running longitudinally along the blade. Specifications 452,503, [Group II], and 573,740 are referred to.

Inventors

No inventors recorded.

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