Fluidized bed reactor and method for forming a metal carbide coating on a substrate containing graphite or carbon

Claim 1

A method for forming a metal carbide coating on a carbon or graphite containing substrate in a fluidized bed furnace having a coating chamber in which the coating reaction occurs comprising the steps of: (a) feeding a fluidizing gas into said furnace to fluidize a bed of particles inclusive of said carbon or graphite containing substrate; (b) forming a metal halide vapor by reacting a halide gas with a carbide forming metal M selected from Group IVb through VIIb of the periodic table; (c) combining said metal halide vapor with said fluidizing gas; (d) maintaining said metal halide vapor in said chamber with said metal halide vapor at a partial pressure which is subatmospheric; and (e) maintaining the temperature of said fluidized bed at a temperature above 1500° C. and at the halide vapor partial pressure of step (d) so that said temperature and pressure cause said metal halide vapor to favor a chemical reaction with said carbon or graphite containing substrate in accordance with the following overall chemical equation: 2MX+2C→2MC+X.sub.2, wherein M is selected as defined above and X is a halide gas for forming said metal carbide coating.

Claim 2

A method for forming a metal carbide coating on a carbon or graphite containing substrate in a fluidized bed furnace having a coating chamber in which the coating reaction occurs comprising the steps of: (a) feeding a fluidizing gas into said furnace to fluidize a bed of particles inclusive of said carbon or graphite containing substrate; (b) forming a metal halide vapor by reacting a halide gas with a carbide forming metal M selected from Group IVb through VIIb of the periodic table; (c) combining said metal halide vapor with said fluidizing gas; (d) maintaining said metal halide vapor in said chamber with said metal halide vapor at a partial pressure which is subatmospheric; and (e) maintaining the temperature of said fluidized bed at a temperature above 1500° C. and at the halide vapor partial pressure of step (d) so that said temperature and pressure cause said metal halide vapor to favor a chemical reaction with said carbon or graphite containing substrate in accordance with the following overall chemical equation: 2MX+2C→2MC+X.sub.2, wherein M is selected as defined above and X is a halide gas for forming said metal carbide coating.