Patent GB-976468-A (GB)
IPC: H05B3/14
Filed: 1960-10-24
Abstract: A dense oxidation proof heat-resistant body is formed by impregnating a preliminary porous body consisting of 30-90% by volume of SiC with 10-70% by volume of an alloy principally comprising molybdenum silicide.  The impregnating alloy may also contain 1-15% silicon alloys of members of the groups W, Cr, Ta, Nb, V, Hf, Zr or Ti together with up to 30% by weight of one or more of the elements Al, Be, Ca, Ce, Co, Cu, Mg, Fe, Mn, Ni, C and B.  Minor amounts of borides, aluminides, and titanides of certain highmelting metals may be included in the impregnating alloy.  The preliminary porous body is shaped from one or more of the following, hexagonal SiC, cubic SiC, graphite, amorphous carbon, and carbon containing carbonizable material, in the case of the three latter substances the SiC is formed in situ during the impregnation process. The final body may have an optional oxide component comprising up to 20% volume of mixed oxides selected from the elements Al, Be, Ce, Cr, Hf, Mg, Ti, Si, Zr, Th, Y and other rare earth metals.  In an example, the SiC body impregnated with the molybdenum silicide alloy is heated in air to form a film of SiO2 on the surface and so seal the pores.  Generally, the bodies are prepared by coating the porous SiC body with the required amount of alloy powder held in position by a paper binder and heating in a carbonizing atmosphere to effect infiltration of the alloy into the pore space, the residual porous cake loosely adhering to the surface after impregnation being subsequently removed. Examples are given of the preparation of hollow and solid electrical resistance heating elements.  Reference has been directed by the Comptroller to Specification 936,118.ALSO:A dense oxidation-proof heat-resistant body is formed by impregnating a preliminary porous body consisting of 30-90% by volume of SiC with 10-70% by volume of an alloy principally comprising molybdenum silicide.  The impregnating alloy may also contain 1-15% silicon alloys of members of the group W, Cr, Ta, Nb, V, Hf, Zr or Ti together with up to 30% by weight of one or more of the elements Al, Be, Ca, Ce, Co, Cu, Mg, Fe, Mn, Ni, C and B.  Minor amounts of borides, aluminides, and titanides of certain high melting metals may be included in the impregnating alloy. The preliminary porous body is shaped from one or more of the following, hexagonal SiC, cubic SiC, graphite, amorphous carbon, and carbon containing carbonizable material, in the case of the three latter substances the SiC is formed in situ during the impregnation process.  The final body may have an optional oxide component comprising up to 20% volume of mixed oxides selected from the elements Al, Be, Ce, Cr. Hf, Mg, Ti, Si, Zr, Th, Y and other rare earth metals.  In an example, the SiC body impregnated with the molybdenum silicide alloy is heated in air to form a film of SiO2 on the surface and so seal the pores.  Generally the bodies are prepared by coating the porous SiC body with the required amount of alloy powder held in position by a paper binder and heating in a carbonizing atmosphere to effect infiltration of the alloy into the pore space, the residual porous cake loosely adhering to the surface after impregnation being subsequently removed.  Examples are given of the preparation of hollow and solid electrical resistance heating elements.  Reference has been directed by the Comptroller to Specification 936,118.