Method for recovering carbon fibers from waste carbon/carbon composite

Abstract

A method for recovering carbon fibers from a waste carbon / carbon composite comprises the following steps: (1) cutting resin-based carbon / carbon composite waste into blocks of 10 cm<3> plus / minus 3 cm<3>, and adding the blocks to a reaction kettle; (2) preparing medium-strong acid and alkali solutions with low boiling point, adding the solutions to the reaction kettle, performing microwave heatingto enable temperature in the kettle to be at 50-120 DEG C, and preserving heat for 1-15 min; (3) adding an alcohol organic solvent with concentration being 10%-50% of to the reaction kettle, and performing full stirring for uniformly mixing solid-liquid substances; (4) performing microwave heating to enable temperature of the kettle to reach 150-280 DEG C and a fluid in the kettle to be in a supercritical state, preserving heat for 1-15 min, and performing cooling; (5) extracting a solid material, washing the solid material to be neutral and drying the solid material at constant temperature toobtain recovered carbon fibers. The recovery method is low in time consumption and energy consumption, quality retention rate of the recovered carbon fibers is higher, cost of recovery of the carbonfibers from the carbon / carbon composite can be reduced remarkably, and efficient recovery and resourceful recycling of the carbon / carbon composite waste are realized.

Description

technical field [0001] The invention relates to a method for recycling carbon fibers in waste carbon-carbon composite materials, in particular to a microwave-assisted supercritical method for recycling carbon fibers in waste carbon-carbon composite materials. Background technique [0002] Carbon / carbon composite materials are considered to be the most promising due to their advantages of low density, high strength, high specific modulus, high thermal conductivity, low expansion coefficient, good friction performance, good thermal shock resistance and high dimensional stability. One of the promising high-temperature materials, it has been widely used in aerospace, automobile industry, military industry, medicine and other fields. However, after a certain number of years, the mechanical properties such as tensile and compressive properties can no longer meet the actual needs, and they cannot be used any longer, which leads to the generation of a large amount of waste carbon-ca...

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Problems solved by technology

[0003] At present, among carbon-carbon composite waste materials, carbon fiber recycling methods include mechanical physical methods, energy recovery methods, heat recovery methods, and chemical recovery methods. These methods all have problems such as low recovery efficiency, poor quality of recycled fibers, There are many problems such as serious surface area carbon, serious loss of mechanical properties, and large energy consumption.

[0004] Chinese invention patent CN103333360A discloses a method for efficiently recovering carbon fibers in carbon / carbon composite waste materials in the form of supercritical fluid, but the method has the following defects: the traditional electric heating mode is used to heat the high-temperature reactor to achieve At the supercritical point, it takes a long time to heat up, and the energy loss is large; the cycle time required for a single operation is long, the production efficiency is low, and the production cost is high

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