A kind of electromagnetic shielding composite material and preparation method thereof
A composite material and electromagnetic shielding technology, applied in chemical instruments and methods, other chemical processes, etc., can solve problems such as loss of magnetism, easy oxidation, and unfavorable electromagnetic shielding performance, and achieve good electromagnetic shielding performance and high temperature resistance.
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[0022] The preparation method includes: preparing a resin carbon interface layer on a prefabricated body SiC fiber reinforcement by impregnation pyrolysis; preparing Si- O-C matrix.
[0023] The impregnation pyrolysis method includes: using phenolic resin ethanol solution as a precursor, preparing a resin-carbon interface layer by impregnating pyrolysis, the concentration of phenolic resin is 10%-30% according to the mass fraction, the pyrolysis temperature is 800-1000°C, and the holding time is 2h;
[0024] Preparation of Si-O-C matrix by polymer vacuum impregnation pyrolysis method includes: using polysiloxane xylene solution as a precursor, the mass fraction of polysiloxane in xylene is 20% to 40%, and the pyrolysis temperature is 900 ~1300°C, holding time 2h, impregnation and pyrolysis cycles 12 times, the porosity of the prepared composite material is 18%-20%.
[0025] Preferably, the process parameters for the preparation of the resin-carbon interface layer are: the co...
Embodiment 1
[0029] The continuous SiC fiber is woven into a fiber preform, and the structure is as attached figure 1 As shown, the prefabricated body structure is a 2.5-dimensional structure with shallow intersecting bends, and the fiber volume fraction is 40%. The resin-carbon interface layer is prepared by dipping and pyrolyzing the phenolic resin ethanol solution as the precursor, and the concentration of the phenolic resin is 10% according to the mass fraction. , the pyrolysis temperature is 1000℃, and the holding time is 2h; the Si-O-C matrix is prepared by the polymer vacuum impregnation pyrolysis method, and the polysiloxane xylene solution is prepared as the precursor. The mass of polysiloxane in xylene The fraction is 30%, put the fiber prefabricated body into the suction filter bottle, vacuumize, open the valve, let the precursor solution flow into the bottle, turn off the vacuum bottle pump after 5 minutes, take out the prefabricated body, put it into the vacuum furnace to hea...
Embodiment 2
[0031] The difference between this example and Example 1 is that the concentration of the phenolic resin solution for preparing the resin carbon interface layer is 15%. Other processing parameters are identical with embodiment 1.
[0032] The composite material prepared in Example 2 was characterized, and the thickness of the resin-carbon interfacial layer was increased to an average of 0.6 μm. The electromagnetic shielding performance test results show that the total electromagnetic shielding effectiveness exceeds 20 dB, and compared with Example 1, the contribution of absorption to the electromagnetic shielding effectiveness is weakened. The shielding effectiveness of the composite material remains above 15dB after oxidation in air at 900°C for 4 hours.
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