▎ 摘　　要

NOVELTY - Preparing porous silicon nitride ceramic material involves: (S1) preparing graphene oxide aerogel from the graphene oxide dispersion liquid and an amino trimethylene phosphonic acid crosslinking agent by using aqueous ammonia as an alkali catalyst and adopting a hydrothermal method; (S2) firstly pouring a carboxymethyl cellulose solution into a graphene oxide aerogel block, then stirring, finally slowly evaporating a solvent to enable carboxymethyl cellulose to be precipitated on the surface of graphene oxide to obtain graphene oxide/carboxymethyl cellulose aerogel, then using a tert-butyl alcohol aqueous solution as a replacement solvent, removing tert-butyl alcohol by a carbon dioxide freeze-drying method to obtain graphene oxide/carboxymethyl cellulose aerogel, and crushing the aerogel to obtain aerogel powder. USE - Preparing porous silicon nitride ceramic material. ADVANTAGE - The pore-forming agent combination method is to add graphene oxide/carboxymethyl cellulose aerogel powder to the silicon nitride ceramic slurry, so that the silicon nitride ceramic material has pores and does not produce harmful gases, which solves the problem of existing porous materials. The problems of low porosity, uneven distribution of pores, environmental pollution and complex preparation process exist in the preparation of silicon nitride ceramic materials are solved. DETAILED DESCRIPTION - Preparing porous silicon nitride ceramic material involves: (S1) preparing graphene oxide aerogel from the graphene oxide dispersion liquid and an amino trimethylene phosphonic acid crosslinking agent by using aqueous ammonia as an alkali catalyst and adopting a hydrothermal method; (S2) firstly pouring a carboxymethyl cellulose solution into a graphene oxide aerogel block, then stirring, finally slowly evaporating a solvent to enable carboxymethyl cellulose to be precipitated on the surface of graphene oxide to obtain graphene oxide/carboxymethyl cellulose aerogel, then using a tert-butyl alcohol aqueous solution as a replacement solvent, removing tert-butyl alcohol by a carbon dioxide freeze-drying method to obtain graphene oxide/carboxymethyl cellulose aerogel, and crushing the aerogel to obtain aerogel powder; (S3) weighing silicon nitride powder, a sintering aid, aerogel powder, a glycerol defoamer and deionized water according to a certain proportion, uniformly stirring, and then putting the slurry into a sealed container to age the slurry for 12 hours to obtain porous silicon nitride ceramic slurry; (S4) drying the slurry until no deformation is generated, de-molding, removing the glue to obtain a blank body, heating at 10-20 ℃/minute during glue removal, gradually heating to 520-650 ℃ for 10-30 minutes, heating the blank body in a sintering furnace to remove aerogel components in a blank body, and leaving uniformly distributed pores; and (S5) completing sintering and high-temperature sintering under the nitrogen atmosphere by adopting step-type heating at a heating speed is 15-20 ℃/minute, where the calcining temperature is 1700-1800 ℃, and the heat preservation time is 2 hours.