A silicon carbide fiber with radial gradient distribution of heterogeneous elements and its preparation method and equipment

Abstract

The invention discloses a silicon carbide fiber with radial gradient distribution of heterogeneous elements and its preparation method and equipment. The silicon carbide fiber contains two kinds of heterogeneous elements Be and B. Radial gradient graduation, the core layer of the silicon carbide fiber, the Be content ≥ B content; the middle layer of the silicon carbide fiber, the B content ≥ Be content; the surface layer of the silicon carbide fiber is BN, so The two heterogeneous elements, Be and B, are introduced during the non-melting treatment process, and the BN surface layer is formed in situ during the preparation process of the silicon carbide fiber. The SiC fiber obtained by the invention contains almost no oxygen, has a silicon-carbon composition close to the stoichiometric ratio of the theoretical value, and has excellent mechanical properties, high temperature resistance and oxidation resistance. In addition, it has an in-situ formed BN interface layer, which can be directly used in the preparation of composite materials.

Description

technical field [0001] The invention discloses a silicon carbide fiber with radial gradient distribution of heterogeneous elements, a preparation method and equipment thereof, and belongs to the field of continuous silicon carbide fiber preparation. Background technique [0002] Due to its unique characteristics of high strength and high modulus, high temperature resistance, oxidation resistance, corrosion resistance, radiation resistance, high hardness and low density, continuous fine SiC fiber is an ideal choice for composite fiber reinforcement under harsh working conditions. [0003] The thin-diameter continuous SiC fiber is prepared from a polymer precursor (usually polycarbosilane (PCS)) through high-temperature heat treatment processes such as melt spinning, non-melting treatment, cracking and ceramicization. Generally speaking, by controlling and adjusting the ratio of C and Si elements in the fiber to achieve an ideal situation of 1:1, the high temperature resistanc...

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Problems solved by technology

[0006] However, in the prior art, doping is basically single-heteroelement doping. Even if there are a few reports on double-heteroelement doping, there is no special design for the step-by-step in the fiber, which is insufficient. The performance of each element is utilized. In addition, the current preparation method is step-by-step for doping and interface layer. First, the precursor containing heterogeneous elements is synthesized, and after the finished silicon carbide fiber is made, then the silicon carbide fiber Depositing an interface layer on the surface, such a preparation process is not only complicated but also costly, which is not conducive to large-scale industrial production

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