Fluidized bed reactor and method for forming a metal carbide coating on a substrate containing graphite or carbon
AssigneeAdvanced Ceramics Corporation
InventorJeffery W. Lennartz
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Abstract
A fluidized bed reactor arrangement and method for forming a metal carbide coating on a substrate containing graphite in which a bed of particles inclusive of the substrate is fluidized using a fluidizing gas containing a metal halide vapor formed by reacting a metal halide gas with a carbide forming metal selected from Group IVb through VIIb of the periodic table and maintaining the temperature of the fluidized bed above 1500.degree. C.
Claims5
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.degree. 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.fwdarw.2MC+X.sub.2,
- wherein M is selected as defined above and X is a halide gas for forming said metal carbide coating.
Dependencies are inferred from the claim text.