Preparation And Performance Of Graphene/Metal Oxide Composite Ceramics

In this paper graphene as strenghen phase,the graphene/Al₂O₃ composite ceramics was fabricated by vacuum hot-pressing sintering,planetary ball mlling as mixing in the process.The influence of the sintering conditons,as temperatuer and pressure,on the microstructure,hard,fracture toughness and electrical conductivity was studied in this article.The main research content is as follows.Several methods preparation of graphene were studied,hummers method is the best technology.Compare with staudenmaier and brodie methods,hummers method preparation of graphene shows a better dispersity.Results of the microstructure show that grain size and density of graphene/Al₂O₃ composite ceramics are increased with the increase of the sintering temperature.Changing hot-press pressure have certain influence on grain size and density of graphene/Al₂O₃ composite ceramics,but less obvious.Grain size and density of composite ceramics are decrease with the increase of graphene.When content of graphene was more than 4wt%,aggregation of graphene was happened,and the more content of graphene the more aggregation were happened.The results of mechanical property show 91.9% increase in fracture toughness for the Al₂O₃ ceramic composites have been acheived by adding 1wt% graphene and sintering temperature was considered as 1400?.Toughening mechanism was researched.Experimental results show the crack deflection,crack bridging and the pullout of graphene are the toughening mechanisms for higher fracture toughness of the graphene/Al₂O₃ composite ceramics.Analyze of the electrical conductivity show:Although increase of sintering temperature an pressure was favorable to the electrical conductivity,but the content of graphene is the greatest influence in electrical conductivity.When other factors are fixed,with the content of graphene from 0 to 10wt%,electrical conductivity improved significantly.The electrical conductivity is 1031.8S/m for 10wt% graphene and just10-13S/m for pure Al₂O₃ ceramic,when sintering temperature is 1300?.