Abstract: A process for the preparation of a carbon yarn product includes the steps of pyrolizing raw carbonaceous yarn comprising a plurality of carbon fibers, at a temperature above about 650° F.; flexing the pyrolized yarn to substantially break fiber-to-fiber bonding between the fibers; and, exposing the yarn to a temperature sufficient to carbonize the pre-carbonized yarn to a final and higher carbon assay. A flexible yarn element (10) includes a plurality of carbon filaments (11) wherein each filament (11) is in contact with at least one other filament 11. A sizing material at least partially coats the plurality of filaments (11), wherein the sizing material of each filament (11) is substantially separated from the sizing material of the at least one other filament (11) in contact therewith.

Abstract: In a process for continuously pulling a web of tows of carbonizable material under tension through an oxidizing oven, the web is introduced into the oxidizing oven by initially feeding a leader in the form of a web of heat-resistant cloth through the oven and then heating the oven if the oven is not already hot. The trailing edge of the leader which remains outside of the oven is then spliced to the leading edge of the web of carbonizable tows, and the leader is used to pull the web of carbonizable tows into and through the hot oven. Use of the heat-resistant leader greatly minimizes wastage within the web of carbonizable tows. Splicing of the trailing edge of the lead to the leading edge of the web of carbonizable tows is accomplished by taping, stitching and folding the two edges to form loops therein into which elongated rods are inserted. The two edges are then secured within a splice bar, the opposite halves of which define slots for receiving the two edges and the included rods.

Abstract: In a method of producing purified carbonized material from polyacrylonitrile precursor material, the precursor material is initially oxidized and partially carbonized prior to purification treatment to remove alkali and alkaline earth metal impurities. Following purification, the material is substantially completely carbonized. Purification is accomplished by weaving oxidized and partially carbonized tows of the polyacrylonitrile precursor material into a fabric and thereafter contacting the fabric with an aqueous acid solution at an elevated temperature followed by rinsing with a solvent which is substantially free of alkali and alkaline earth metal ions and which is at an elevated temperature. Purification of the tows after partial carbonization thereof limits the amount of tow weight loss and shrinkage occurring after the fabric is formed.

Abstract: In a process for continuously pulling a web of tows of carbonizable material under tension through an oxidizing oven, the web is introduced into the oxidizing oven by initially feeding a leader in the form of a web of heat-resistant cloth through the oven and then heating the oven if the oven is not already hot. The trailing edge of the leader which remains outside of the oven is then spliced to the leading edge of the web of carbonizable tows, and the leader is used to pull the web of carbonizable tows into and through the hot oven. Use of the heat-resistant leader greatly minimizes wastage within the web of carbonizable tows. Splicing of the trailing edge of the lead to the leading edge of the web of carbonizable tows is accomplished by taping, stitching and folding the two edges to form loops therein into which elongated rods are inserted. The two edges are then secured within a splice bar, the opposite halves of which define slots for receiving the two edges and the included rods.

Abstract: Fibrous PAN material in raw or oxidized form is purified of alkali metals, particularly sodium, and alkaline earth metals by treating with an aqueous acid solution such as hydrochloric acid having a concentration of at least 0.5% by weight and preferably at least 3% and a temperature greater than 100.degree. F. and preferably at least 125.degree. F. but not greater than the temperature at which the aqueous acid solution boils, for 5-120 minutes and preferably at least about 15 minutes. An ion exchange occurs between the acid and the PAN material, and alkali and alkaline earth metal salts are formed. The PAN material is then rinsed in solvent such as deionized water which is substantially free of metallic ions at a temperature which is preferably at least about 150.degree. F.

Abstract: In a method of making carbon or graphite yarn, a bundle of single ply precursor yarns is knit into an elongated fabric to facilitate subsequent processing of the yarns. The elongated fabric is pretreated to facilitate carbonization thereof such as by being advanced in the direction of elongation thereof through a cleaning process. Thereafter the yarns remain in the form of the fabric to facilitate processing thereof through at least a carbonization step. The carbonization step may be accomplished by winding the elongated fabric onto skeins to a desired extent and then severing the fabric, following which the skeins are disposed in a carbonizing oven to at least partially carbonize the yarns. Thereafter, the fabric length on each skein may be deknitted, and the resulting bundle of single ply yarns is twisted to form a multi-ply yarn which is then fired to substantially raise the percentage of carbon in the yarns and then graphitized.