Inorganic nonmetal composite wave-absorbing material containing graphene nano layer as well as preparation method and application thereof

[0030] Taking the composite material of 99% alumina powder and 1% graphene as an example, the expandable graphite was first placed in a thermal induction furnace, and the 2 Under the atmosphere, the temperature was raised to 1300° C. within 1 minute, and then cooled to room temperature. The obtained vermicular graphite was ground in a mortar and mixed with α-Al 2 o 3 Powder mixing, using silicon nitride balls and nylon ball milling tanks, and adding NMP as a grinding aid for wet grinding, 500 rpm planetary ball milling for 30 hours, then taking out the powder and drying it, and putting the powder into the graphite mill , using spark plasma sintering (spark plasma sintering, SPS) equipment for sintering.

[0031] The SPS process is carried out under vacuum conditions, with a sintering temperature of 1300 °C, a heating rate of 100 °C / min, and a holding time of 5 min; a two-step pressurization method is adopted, the pressure applied before sintering is 10 MPa, and the pressure ...

[0035] Graphite oxide is first prepared. In 0.15g of graphite, add 5g of potassium persulfate (K 2 S 2 o 8 ), 5g phosphorus pentoxide (P 2 o 5 ) and 30ml of concentrated sulfuric acid, stirred at 80°C for 4.5 hours, added excess deionized water, filtered through a filter membrane and washed with water until the pH value was neutral, and then dried at 60°C. Add 100ml concentrated sulfuric acid and 6g potassium permanganate (KMnO 4 ), the entire mixing process needs to be carried out in an ice bath. The mixture was then stirred at 35°C for 5 days. After that, 1 L of deionized water was added and stirred for 2 hours, and then 50 ml of 30% hydrogen peroxide aqueous solution was slowly added. Filter with a filter membrane and wash with 10% hydrochloric acid three times, and then wash with deionized water until the pH value is neutral. Finally, dialysis removes all impurity ions.

[0036] The prepared graphite oxide was directly added to the silica sol at a mass ratio of 5%...

[0038] With a composition of 95% silicon nitride (Si 3 N 4 ) and 5% graphene composite material as an example, first place the expanded graphite in a vacuumized sealed glass tube, heat it in a (60Hz microwave) microwave oven for 3 minutes, and then cool it down to room temperature. After the obtained vermicular graphite was ground in a mortar, it was mixed with Si 3 N 4 Powder mixing, using silicon nitride balls and nylon ball milling tanks, and adding NMP as a grinding aid for wet grinding, 500 rpm planetary ball milling for 30 hours, then taking out the powder and drying it, and putting the powder into the graphite mill , using hot isostatic pressing furnace equipment for sintering.

[0039] The hot isostatic pressing sintering process is carried out under vacuum conditions. The sintering temperature is 1400°C, the heating rate is 500°C / h, and the holding time is 1h; the pressure during the sintering process is 150MPa. The insertion loss value of the composite material p...