COMPOSITE MATERIAL, VARIANTS AND METHOD FOR PRODUCING THE SAME

摘要

The present invention pertains to the production of heat-resistant composite materials that can be used in engine units with important strains, in an oxidising environment and at temperatures exceeding 1100 DEG C. This material is composed of a microscopic three-dimensional network (random cells) made of tungsten and/or molybdenum, wherein said network is filled with nickel monoaluminide or with alloys thereof. The amount of aluminium in this composition ranges from 35 to 48 atomic %, while the thickness of the cell walls in the network ranges from 1 to 5 mu m. This composite material, which includes a refractory metal and nickel monoaluminide, is characterised in that the nickel may be replaced with niobium and/or titanium in a quantity of up to 12 atomic %. The Al2O3 oxide film formed during the open-air heating process is continuous and closes the openings at the surface of the metal network. The film also protects the composition against oxidation and is capable of self-regeneration in case of damage. The nickel monoaluminide is obtained by pulverising an alloy and by sifting the product in order to obtain the target fraction. Before the compacting process, the refractory metal (tungsten and/or molybdenum) is applied on the surface of the granules by thermally decomposing the vapours of the corresponding carbonyl in a spouted bed. After the compacting process, the tungsten forms a continuous network having its cells filled with nickel monoaluminide. The fluidity boundary of the composition upon compression is of 110 Mpa at 1200 DEG C. No oxidation has been detected in the composition nor in the pure compact nickel monoaluminide during the continuous open-air heating process, and the oxidation detected from the gain only started at a temperature exceeding 1250 DEG C.