Method for producing non-core beta silicon carbide fibers

A method for producing non-core beta silicon carbide fibers, comprising step of:

• determining an initial fiber formation temperature and a drop temperature for each batch of polycarbosilane in advance, and then multifilament polymeric fiber is spun by extruding a polycarbosilane melt, for which polycarbosilane is loaded to an extruder at room temperature, heated to an optimal spinning temperature selected in the range from a temperature higher than the initial fiber formation temperature and lower than the drop temperature, for producing polycarbosilane melt, the polycarbosilane melt is forced through a spinneret at a pressure from 1.5 to 4.0 MPa for forming the polymeric fibers that are stepwise cooled in an inert atmosphere to room temperature, followed by curing, the polymeric fibers are received by a fiber winding device having a winding rate greater that a polymeric fiber feed rate, thus forming spun polymeric fibers,
• carrying out thermooxidative cross-linking, for which the formed spun polymeric fibers, that are wound on graphite bobbins are cured in an oxidation furnace at a temperature in a range from 175 to 250 degrees C. at a heating rate of 3-10 degrees C./h until the spun polymeric fiber weight is increased by 6-15%, thus producing cured polymeric fiber;
• carbonizing the produced cured polymeric fiber is with a conversion into ceramic phase, for which the cured polymeric fiber is treated in a furnace in an inert atmosphere or in vacuum with stepwise heating to 1100-1300 degrees C. at a heating rate 2.5-5 degrees C./min, and, the cured polymeric fiber is held at temperatures of 400, 700 and 1250 degrees C. for 30 minutes each, and then the furnace is cooled;
• and
• finishing the produced non-core beta silicon carbide fiber using a finish.