Preparing method of large-size low-heat-conductivity-coefficient high-strength foam carbon

Abstract

The invention discloses a preparing method of large-size low-heat-conductivity-coefficient high-strength foam carbon. By adopting pitch with a high softening point as a raw material and adopting a spherical or one-dimensional structural material as a compound reinforcement, the foam carbon with a good integral structure and a uniform pore structure is prepared through a foaming process, wherein the diameter of the foam carbon is 200 mm, the height is 200 mm, the heat conductivity coefficient is 0.15 W / (m.k), the compression strength is higher than 30 MPa, the volume shrinkage rate at 1500 DEG C is lower than 3%, and the density is 0.3-0.8 g / cm<3>. The foam carbon is suitable to be used as a structural thermal insulation material, a heat preservation material and a wave absorption material, and can be widely used for the fields of spaceflight, aviation, navigation, energy-saving building, and the like.

Description

Technical field: [0001] The present invention relates to a large-size, low-thermal-conduction, high-strength foam carbon preparation technology, in particular to a carbon foam with a diameter of 200mm, a height of 200mm, a thermal conductivity lower than 0.15W / (m.k), a compressive strength higher than 30MPa, and a temperature of 1500°C. The volume shrinkage rate is less than 3%, and the density is 0.3-0.8g / cm 3 And the preparation method of foamed carbon with good overall structure and uniform pore structure. Background technique: [0002] As a honeycomb carbonaceous functional material, foam carbon not only has high strength, low thermal conductivity, low density, low thermal expansion coefficient, high temperature resistance, oxidation resistance, acid resistance, alkali resistance, low water absorption, no volatile substances, no Toxic gas, and has good formability and processability. Therefore, foam carbon can be widely used as thermal insulation materials for aerospac...

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Problems solved by technology

Among them, the main factors restricting the performance and structure control of low thermal conductivity foamed carbon are reflected in the following aspects: 1) Phenolic resin is a main raw material for preparing low thermal conductivity foamed carbon, but the foamed carbon made from this raw material is degassed under high pressure Or it is easy to break during high-temperature carbonization, which makes it difficult to control the overall structure of carbon foam, especially for the preparation of large-sized carbon foam; The compressive strength is increased to 25MPa, but the mesophase carbon microspheres are heat-treated by high-temperature graphitization, and more solid-liquid interfaces are easily produced during the composite process with the carbonaceous precursor, which leads to the impact strength and tensile strength of the foamed carbon. 3) Carbon fibers with one-dimensional structure, chopped carbon fibers, carbon nanofibers, and carbon nanotubes can improve the strength of carbon foam to a certain extent, but mainly increase the tensile strength. The contribution to compressive strength is not large, and its own thermal conductivity is high; 4) In the process of preparing large-scale carbon foam, the carbonaceous precursor or matrix carbon is greatly affected by heat transfer or thermal field, so the overall structure of carbon foam and The uniformity of the pore structure is difficult to control; 5) The volume shrinkage rate of foamed carbon at high temperature is also a key factor that needs to be investigated in the practical application of foamed carbon, but none of the current patents or literature deals with this issue

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