▎ 摘　　要

NOVELTY - Preparing graphene oxide coated silicon nitride composite powder comprises: (i) adding silicon nitride powder into hydrogen peroxide, dispersing to obtain surface oxidized silicon nitride powder; and (ii) ultrasonically dispersing oxidized silicon nitride powder in hydroalcoholic mixed solution, adding coupling agent into hydrolysis solution, adjusting pH to 8-10, stirring to obtain coupling agent surface modified silicon nitride suspension, then adjusting the pH to 3-5, mixing the suspension with aqueous dispersion of graphene oxide, stirring by ultrasonic agitation, separating and drying. USE - The graphene oxide coated silicon nitride composite powder is useful for toughening and strengthening ceramic materials (claimed). ADVANTAGE - The graphene oxide coated silicon nitride composite powder improves the mechanical property of the ceramic material. DETAILED DESCRIPTION - Preparing graphene oxide coated silicon nitride composite powder comprises: (i) adding silicon nitride powder into hydrogen peroxide, dispersing at 60-100 degrees C under magnetic stirring condition to obtain surface oxidized silicon nitride powder; and (ii) ultrasonically dispersing surface oxidized silicon nitride powder in hydroalcoholic mixed solution, then adding 2.5-10% coupling agent into hydrolysis solution, continuously and ultrasonically mixing at 60-90 degrees C, adjusting its pH to 8-10, stirring under magnetic condition for 2-4 hours to obtain coupling agent surface modified silicon nitride suspension, then adjusting the pH of silicon nitride suspension to 3-5, mixing the suspension with aqueous dispersion of graphene oxide with a pH of 8-10, stirring the mixture by ultrasonic agitation until the coated particles are all precipitated, separating and drying.