Z direction continuous carbon fiber prefabricated body

Abstract

The invention relates to an improvement on Z direction continuous carbon fiber prefabrication, which is characterized in that: a planar laminated carbon fiber fabric is weftless carbon fiber cloth formed by arranging long fibers in an interlaminar crossing way. A Z direction structure is stable, and basically undamaged continuous carbon fibers are arranged in the three-dimensional direction of the prefabricated body, so that the isotropy of the prefabricated body is enhanced, and a three-dimensional structural framework is formed. A chopped fiber web in which fibers are randomly distributed is introduced between adjacent layers, and a plurality of holes are distributed randomly, so that the introduction and uniform distribution of matrix carbon are facilitated. Due to the adoption of the weftless fabric, the needle threading resistance is reduced, the Z direction continuous fiber interval can be enlarged, and the Z direction continuous fiber introducing efficiency is improved; and large K-beam carbon fibers can be adopted, so that the cost can be lowered by 40-60 percent. The prefabricated body provided by the invention can be taken as a structural material, a functional material and a structural-functional material.

Description

technical field [0001] The invention relates to a carbon fiber three-dimensional prefabricated body with continuous carbon fiber in the Z direction, in particular to the improvement of the interlayer fabric of the existing continuous carbon fiber prefabricated body. Background technique [0002] To prepare various high-performance C / C composite materials, it is necessary to prepare a three-dimensional carbon fiber prefabricated body. The three-dimensional carbon fiber prefabricated body (hereinafter referred to as the prefabricated body) means that the X, Y, and Z directions have expected structural strength. However, due to the poor cohesion of the carbon fiber surface due to the smooth surface, only X-direction and Y-direction carbon fibers or woven fabrics are used for lamination, and the interlayer connection strength is extremely low. Therefore, the prior art mostly uses acupuncture technology. Fiber reinforcement is introduced in the Z direction to obtain prefabricated...

AI Technical Summary

Problems solved by technology

However, due to the poor cohesion of the carbon fiber surface due to the smooth surface, only X-direction and Y-direction carbon fibers or woven fabrics are used for lamination, and the interlayer connection strength is extremely low. Therefore, the prior art mostly uses acupuncture technology. Introduce fiber reinforcement in the Z direction to obtain a prefabricated body with three-dimensional fiber connections, for example: U.S. Patent US5869411, Chinese Patents 96121709, 95191073, CN101575766, and the applicant’s previous patent application CN02138191.7, etc. all use acupuncture to form prefabricated bodies

The prefabricated body that uses acupuncture to introduce Z-direction fibers to obtain interlayer connection strength still has shortcomings: for example, introducing interlayer connection fibers in the Z direction by needle punching can certainly enhance the Z-direction structural strength of the preform, but objectively First, due to the limited ability of needle punching to pass through the thickness, the thickness of the Z-direction fiber connection between layers is also limited; secondly, the Z-direction connection fiber is a short fiber produced by needle punching, and the needle punching process makes the original X-direction and Y-direction The fibers are damaged in the Z direction, and the Z direction strength (interlayer tensile and shear resistance) is always not very high due to two reasons, and it is difficult to make a composite material with high Z direction strength and overall structural strength.

There are many warp and weft fiber interweaving points in the braided fabric, and in order to ensure the flatness of the woven fabric between layers, it is usually necessary to pre-tension, so that a moment is formed at the intersection point of warp and weft, and the distance between the moment points of the woven fabric and the fine K-bundle fiber is relatively short. Tension leads to high resistance and friction when puncturing in the Z direction. It is difficult to puncture large-thickness products (such as ≥300mm), and it is difficult to puncture. Increasing the puncturing force will easily cause uneven interlayer cloth, which will also affect the prefabricated body. Secondly, the introduction of continuous fiber thick steel needle will also damage the X and Y direction fibers, which will objectively reduce the performance of X and Y directions; moreover, the continuous fiber adopts a small spacing such as about 1.0-1.4 mm, Not only is it more difficult to manufacture, but it also causes greater damage to the plane X and Y fibers, and it is easier to cause wrinkles in the plane fabric, which affects the plane mechanical properties

In addition, small K bundles of carbon fibers not only have high cost, but also have many overlapping nodes in weaving, which may easily cause the deposition at the interface of fiber overlapping points, which may easily lead to uneven introduction of carbon into the subsequent matrix, and the overlapping of braided fibers is slightly arched, and the interweaving point Fiber bending also results in reduced planar performance

All of these will reduce the mechanical properties of the prefabricated body, or limit the improvement of its performance

If the carbon fiber fabric is stacked layer by layer on the prefabricated steel needle plate arranged in the Z direction, although the above-mentioned big problem of passing resistance can be overcome, not only the production efficiency is obviously greatly reduced, the actual industrialization is not easy to accept, and other problems have not yet been overcome.

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