Gas permeable stopper rod

A refractory stopper rod for use in the continuous casting of molten metal comprising:

• a co-pressed body portion and an integral porous nose section of a carbon-bonded graphite refractory grain composition, said body having an elongated cylindrical shape and an axial bore formed therein with an opening at a first, upper end adapted to be attached to a pressurized source of inert gas, said bore terminating at a second, lower end adjacent to an inner surface of said porous nose section, the refractory grains of said body portion and integral nose section being bonded together along an interface region between said body and nose section by a carbon bond during firing, the nose section having an outer surface adapted to be in contact with said molten metal and having a controlled pore size defined by voids between adjacent grains whereby, in use, pressurized gas permeates the pores of said nose section and exits said pores to enter the molten metal as a fine dispersion of gas bubbles emitted from the exterior surface of said nose section and wherein said pore size is sufficiently small to prevent molten metal from permeating said nose section in the event of gas depressurization within said bore.

A refractory stopper rod for use in casting molten metal comprising:

• a co-pressed body portion and an integral porous nose section having an exterior surface adapted to be in contact with the molten metal and having a controlled pore size, said stopper rod having bore means adapted to introduce a pressurized gas to an interior surface of said nose section whereby, in use, the pressurized gas permeates said nose section and enters the molten metal as a fine dispersion of bubbles emitted from the exterior surface of said nose section, wherein the porous nose section has a controlled pore size defined by a mean pore diameter of about 10 microns which is sufficient to permit the pressurized gas to permeate therethrough while also preventing the molten metal to permeate in a reverse direction through said nose section in an event of gas depressurization.

A refractory stopper rod for use in casting molten metal comprising:

• a co-pressed body portion and an integral porous nose section having an exterior surface adapted to be in contact with the molten metal and having a controlled pore size in which the nose section has a mean pore size on the order of about forty (40) times greater than that of the body portion, said stopper rod having bore means adapted to introduce a pressurized gas to an interior surface of said nose section whereby, in use, the pressurized gas permeates said nose section and enters the molten metal as a fine dispersion of bubbles emitted from the exterior surface of said nose section.

A refractory stopper rod for use in the continuous casting of molten metal comprising:

• a co-pressed body portion and an integral porous nose section of a carbon-bonded graphite refractory grain composition, said body having an elongated cylindrical shape and an axial bore formed therein with an opening at a first, upper end adapted to be attached to a pressurized source of inert gas, said bore terminating at a second, lower end adjacent to an inner surface of said porous nose section, the nose section having an outer surface adapted to be in contact with said molten metal and having a controlled mean pore size of about 10 microns, whereby, in use, pressurized gas permeates said nose section and is injected into the molten metal as a fine dispersion of gas bubbles emitted from the exterior surface of said nose section and wherein said pore size is sufficiently small to prevent molten metal from permeating said nose section in the event of gas depressurization within said bore.

A refractory stopper rod for use in the continuous casting of molten metal comprising:

• A co-pressed body portion and an integral porous nose section of a carbon-bonded alumina graphite refractory material, said body having a mean pore size on the order of about 0.25 microns and an elongated cylindrical shape and an axial bore formed therein with an opening at a first, upper end adapted to be attached to a pressurized source of inert gas, said bore terminating at a second, lower end adjacent to an inner surface of said porous nose section, the nose section having an outer surface adapted to be in contact with said molten metal and having a controlled mean pore size of about 10 microns whereby, in use, pressurized gas permeates said nose section and is injected into the molten metal as a fine dispersion of gas bubbles emitted from the exterior surface of said nose section and wherein said pore size is sufficiently small to prevent molten metal from permeating said nose section in the event of gas depressurization within said bore.