GB723842A - Process for the manufacture of composite metal-ceramic material - Google Patents

Abstract

<PICT:0723842/III/1> <PICT:0723842/III/2> A process for manufacturing refractory and mechanically strong composite material of the type having metallic and ceramic constituents other than siliceous substances in close adhesive relationship for gas turbine blades or other heat engine elements comprises heating separately said constituents to a temperature at which they are in a softened condition and simultaneously and separately spraying said constituents on to a support whereby said metallic and ceramic constituents closely mix on the surface of said support. Apparatus for carrying out the invention comprises an oxyacetylene blow pipe 1 into which metal is fed in the form of a filament 4 so that the jet issuing from the nozzle 5 of the gun carries grains of molten metal which are projected on to a support 6 heated by a furnace 11. Another similar gun 7 is fed with a powdered ceramic constituent from a hopper 9 and this also is projected on to the support 6. On cooling, the composite material is separated from the support. The guns may be operated simultaneously to deposit a mixture of metal and ceramic grains on the support or they may be operated alternately to form fused laminated layers of metal and ceramic on the support. The metal projected from the gun 1 may be steel or an alloy containing nickel, chromium, cobalt. The ceramic constituent is a mixture containing a high proportion of refractory grains, e.g. an oxide, a carbide, a boride, a nitride or a mixture of these substances and a binder which may comprise vitrifying agents e.g. agents having a base of borax or of lithium oxide. In a modification a number of fixed guns are used to deposit metal and ceramic constituents alternately on a travelling or reciprocating support resting on rollers 12. The support may be a mould of metal or refractory material from which the composite material is withdrawn. In a further modification of the invention in order to increase the porosity of the material, one of the constituents is partially replaced by a third constituent which may be an organic or organo-metallic material or a mineral salt which is volatile or soluble or decomposable by heat, e.g. plastic materials.