Method for the continuous production of carbides

Claim 1

The method of making silicon carbide-bearing material comprising the steps of: introducing into a heat resistant vessel a relatively coarse particulate carbon-bearing material; introducing a sufficient flow of non-reactive gas through a gas distribution member to bring the particulate carbon-bearing material into the state of fluidization; applying an electric potential between electrodes positioned to be in direct contact with the fluidized carbon-bearing material particles to cause electric current to flow through the bed material between the electrodes in direct contact with the fluidized bed and at a rate sufficient to heat the said fluidized bed to a temperature in excess of the temperature of decomposition of silicon carbide; introducing a finer particulate carbon-bearing material into the fluidized bed of coarser particulate carbon-bearing material; controlling the relative size difference of the coarser and finer particulate carbon-bearing material and the velocity of the fluidizing gas to cause the finer particulate carbon-bearing material to be maintained in a state of dense phase fluidization in a region above the fluidized bed of the coarser particulate carbon-bearing material; removing heat from the zone of the fluidized bed of the finer particulate carbon-bearing material sufficient to cause the temperature of the fluidized bed of the finer particulate carbon-bearing material to be lower than the temperature of the fluidized bed of the coarser particulate carbon-bearing material and below that of the decomposition temperature of silicon carbide, but above that temperature required to form silicon carbide by the reaction of vapor forms of silicon and solid carbon; introducing a silicon-bearing material into the fluidized bed of coarser particulate carbon-bearing material to cause silicon vapors to form and to pass upwardly through the lower temperature fluidized bed of finer particulate carbon-bearing material and to react with the finer carbon-bearing material to form a silicon carbide-bearing material from the fluidized bed furnace.

Claim 2

The method of making silicon carbide-bearing material comprising the steps of: introducing into a heat resistant vessel a relatively coarse particulate carbon-bearing material; introducing a sufficient flow of non-reactive gas through a gas distribution member to bring the particulate carbon-bearing material into the state of fluidization; applying an electric potential between electrodes positioned to be in direct contact with the fluidized carbon-bearing material particles to cause electric current to flow through the bed material between the electrodes in direct contact with the fluidized bed and at a rate sufficient to heat the said fluidized bed to a temperature in excess of the temperature of decomposition of silicon carbide; introducing a finer particulate carbon-bearing material into the fluidized bed of coarser particulate carbon-bearing material; controlling the relative size difference of the coarser and finer particulate carbon-bearing material and the velocity of the fluidizing gas to cause the finer particulate carbon-bearing material to be maintained in a state of dense phase fluidization in a region above the fluidized bed of the coarser particulate carbon-bearing material; removing heat from the zone of the fluidized bed of the finer particulate carbon-bearing material sufficient to cause the temperature of the fluidized bed of the finer particulate carbon-bearing material to be lower than the temperature of the fluidized bed of the coarser particulate carbon-bearing material and below that of the decomposition temperature of silicon carbide, but above that temperature required to form silicon carbide by the reaction of vapor forms of silicon and solid carbon; introducing a silicon-bearing material into the fluidized bed of coarser particulate carbon-bearing material to cause silicon vapors to form and to pass upwardly through the lower temperature fluidized bed of finer particulate carbon-bearing material and to react with the finer carbon-bearing material to form a silicon carbide-bearing material from the fluidized bed furnace.