The invention relates to a method and to a device for stabilizing precursor fibers for the production of carbon fibers. In the method, precursor fibers are first heated to a first temperature and held at the temperature for a predefined duration. Subsequently, the precursor fibers are heated to at least one second temperature, which is higher than the first temperature, and held at said temperature for a predefined duration. During each heating and between the heating steps, the precursor fibers are in a gas atmosphere having a negative pressure in the range between 12 mbar and 300 mbar and having an oxygen partial pressure of 2.5 to 63 mbar. The device has at least one evacuable, elongate vacuum chamber for feeding the precursor fibers through, at least two lock units and at least one heating unit. At least one lock unit is used for the sealed insertion of precursor fibers into the at least one vacuum chamber, while at least one other lock unit is used for the sealed removal of precursor fibers from the at least one vacuum chamber. The heating unit has at least two individually controllable heating elements, which are suitable for heating the at least one vacuum chamber to at least two different temperatures in heating zones which are adjacent in the longitudinal direction.

A method includes a freezing process in which a solution or gel containing cellulose nanofibers is frozen to obtain a frozen component, a drying process in which the frozen component is dried in a vacuum to obtain a dry component, and a carbonizing process in which the dry component is heated and carbonized in a non-combustible atmosphere, and in the carbonizing process, the dry component is heated together with a reducing catalyst and also a material that generates a reducing gas by thermal decomposition.

A method includes a freezing process in which a solution or gel containing cellulose nanofibers is frozen to obtain a frozen component, a drying process in which the frozen component is dried in a vacuum to obtain a dry component, and a carbonizing process in which the dry component is heated and carbonized in a non-combustible atmosphere, and in the carbonizing process, the dry component is heated together with a reducing catalyst and also a material that generates a reducing gas by thermal decomposition.

The invention relates to a method and to a device for stabilizing precursor fibers for the production of carbon fibers. In the method, precursor fibers are first heated to a first temperature and held at the temperature for a predefined duration. Subsequently, the precursor fibers are heated to at least one second temperature, which is higher than the first temperature, and held at said temperature for a predefined duration. During each heating and between the heating steps, the precursor fibers are in a gas atmosphere having a negative pressure in the range between 12 mbar and 300 mbar and having an oxygen partial pressure of 2.5 to 63 mbar. The device has at least one evacuable, elongate vacuum chamber for feeding the precursor fibers through, at least two lock units and at least one heating unit. At least one lock unit is used for the sealed insertion of precursor fibers into the at least one vacuum chamber, while at least one other lock unit is used for the sealed removal of precursor fibers from the at least one vacuum chamber. The heating unit has at least two individually controllable heating elements, which are suitable for heating the at least one vacuum chamber to at least two different temperatures in heating zones which are adjacent in the longitudinal direction.

An example oven for heating fibers includes a chamber having upper and lower portions and a supply structure between first and second ends of the chamber, wherein the supply structure is in communication with a first heating system and is configured to direct first heated gas from the first heating system into the upper portion of the chamber to heat fibers in the upper portion at a first temperature, and wherein the supply structure is in communication with a second heating system and is configured to direct second heated gas from the second heating system into the lower portion of the chamber to heat fibers in the lower portion at a second temperature different than the first temperature such that the upper and lower portions of the chamber maintain the different temperatures without a physical barrier between the upper and lower portion.

An example oven for heating fibers includes a chamber having upper and lower portions and a supply structure between first and second ends of the chamber, wherein the supply structure is in communication with a first heating system and is configured to direct first heated gas from the first heating system into the upper portion of the chamber to heat fibers in the upper portion at a first temperature, and wherein the supply structure is in communication with a second heating system and is configured to direct second heated gas from the second heating system into the lower portion of the chamber to heat fibers in the lower portion at a second temperature different than the first temperature such that the upper and lower portions of the chamber maintain the different temperatures without a physical barrier between the upper and lower portion.

One embodiment is directed to an oven for heating fibers. The oven comprises a plurality of walls forming a chamber and a supply structure disposed within the chamber between first and second ends of the chamber. The supply structure is in communication with a first heating system and is configured to direct heated gas from the first heating system into a first portion of the chamber. The supply structure is in communication with a second heating system and is configured to direct heated gas from the second heating system into a second portion of the chamber.