Patent GB-1099957-A (GB)
Title: Composite carbide flame spray wire or powder
IPC: C04B35/56
Filed: 1965-05-26
Abstract: A flame spray wire or powder for depositing metallic carbide on a substrate comprises a metal carbide (or the metal, its oxide or hydride with sufficient elemental carbon to form the carbide), at least 5% by weight of the carbon, with respect to the carbon in the final carbide, being in free form.  Carbides of W, Ta, Zr, Ti, B, Nb, Hf, Mo, Si, V, Sc, Th, U, Cr and mixtures thereof such as solid solution carbide of Ta, Hf and Zr, are referred to.  The carbon may be present as carbon black, graphite, sugar, carbon or charcoal. If powder is employed, each grain is provided with the necessary carbon, e.g. by coating the grains with a carbon-containing lacquer to provide final grains of 15 to 160 microns size. If a wire is employed, it may be formed of a metal sheath containing therein a mixture of carbide or metal plus the requisite carbon and such tubes may be drawn or swaged to the desired diameter.  Alternatively, wires or rods may be formed from the powdered composite bonded with a plastics binder.  According to Examples (1) a solid solution carbide of composition 4 TaC. 1 (Zr and Hf) C, having a particle size between 10 and 60 microns was coated with a graphite-containing phenolic varnish in aromatic hydrocarbon solvent by mixing.  A coating 0.007" thick was formed on cold, rolled steel using a nitrogen-hydrogen plasma gas mixture and a current of 400 amps. at 72 volts.  (6) The powder of Example 1 was mixed with polythene and extruded into flame spray wires of 1/8 inch diameter.  (7) Tantalum was drawn as a hollow tube of 1/2 inch diameter and then packed with a mixture of tantalum and carbon powder, the amount of carbon being 8% by weight of all the metal present. The composite wire was swaged to 1/8 inch diameter and employed for flame spraying.ALSO:A flame spray wire or powder for depositing metallic carbide on a substrate comprises a metal carbide (or the metal, its oxide or hydride with sufficient elemental carbon to form the carbide), at least 5% by weight of the carbon, with respect to the carbon in the final carbide, being in free form. Carbides of W, Ta, Zr, Ti, B, Nb, Hf, Mo, Si, V, Sc, Th, U, Cr and mixtures thereof such as solid solution carbide of Ta, Hf and Zr. The carbon may be present as carbon black, graphite, sugar, carbon or charoal. If powder is employed, each grain is provided with the necessary carbon, e.g. by coating the grains with a carbon-containing lacquer to provide final grains of 15 to 160 microns size. If a wire is employed, it may be formed of a metal sheath containing therein a mixture of carbide or metal plus the requisite carbon and such tubes may be drawn or swaged to the desired diameter. Alternatively, wires or rods may be formed from the powdered composite bonded with a plastics binder.  According to examples: (1) a solid solution carbide of composition 4 TaC 1(Zr and Hf) C, having a particle size between 10 and 60 microns was coated with a graphite-containing phenolic varnish in aroatic hydrocarbon solvent by mixing.  A coating 0.007 inch thick was formed on cold, rolled steel using nitrogen hydrogen plasma gas mixture and a current of 400 amps. at 72 volts.  (6)The powder of Example 1 was mixed with plythene and extruded into flame spray wires of 1/8 th inch diameter.  (7)Tantalum was drawn as a hollow tube of 1/2 inch diameter and then packed with a mixture of tantalum and carbon powder, the amount of carbon being 8% by weight of all the metal present.  The composite wire was swaged to 1/8th inch diameter and employed for flame spraying.