High-resistivity continuous silicon carbide fiber and preparation method thereof

The invention relates to a high-resistivity continuous silicon carbide fiber and a preparation method thereof. A polycarbosilane ceramic precursor with a high molecular weight, high activity and high ceramic yield is prepared by adopting a segmentation co-fracturing rearrangement method. Fragile ceramic fiber protofilament is prepared through the continuous flash desorption and the slow cooling single suction of molten polycarbosilane, and the continuous silicon carbide fiber with a small diameter, high resistivity and good flexibility and stitchability is directly prepared through cross-linking sizing by a low-oxygen-containing furnace and through self-feedback closed-loop reductive sintering. The prepared high-resistivity continuous silicon carbide fiber has a diameter of 6 microns to 14 microns, tensile strength of 1.8Gpa to 3.5Gpa and a modulus of 140Gpa to 320Gpa; the resistivity of a gradient coating on the surface of the fiber is not less than 1 multiplied by ten to the power of five; each performance