Graphene Oxide Modified Carbon Carbide Ceramics Prepared By Heterogeneous Co-precipitation

Boron carbide?B₄C?ceramics is one of the hardest three kinds of materials,the other two kinds of diamond and cubic boron nitride.Mohs hardness of boron carbide is 9.3.Due to the low density,good strength,high temperature stability and chemical stability characteristics,boron carbide ceramics have a wide range of applications in the wear-resisting material and the field of light armor,especially.But the fracture toughness and flexural strength of boron carbide ceramics are low.This makes its service life be reduced and unable to extend its scope of application because of its brittleness.This topic focuses on fracture toughness and flexural strength of B₄C ceramics,carried out the study of the following several parts:?1?Modified Graphene oxide was prepared by Hummers method?Graphene oxide,GO?,through the water to get rid of the acid in graphite oxide,water pH neutral also helps to increase to oxidation in the process of graphite increases the electrostatic repulsion between layer and layer,are more likely to be stripped to GO.Then ultrasonic stripping process by graphite oxide can be completely transformed into the GO.?2?Using cetyl trimethyl Ammonium bromide?CTAB?are studied out phase coprecipitation reaction process,CTAB on the GO and B₄C work alone,and the effect of mixed together.The study found that CTAB can form stable aqueous solution under ultrasound,in CTAB solution GO powder can precipitate and GO aqueous solution can form a stable suspension,for B₄C powder,while CTAB addition amount for 1-1.6 wt%,can form stable fluid sediment.CTAB was determined by the double variable cross control experiment,the content of the interphase precipitation effect plays a main role,and by further experiments to determine the optimal dosage of CTAB was 1.2 wt%.?3?The discharge plasma sintering process,the preparation of rGO/B₄C composite ceramics,the study found that pressure and sintering temperature on density of rGO/B₄C composite ceramics have a significant impact.When sintering pressure reached more than 50 MPa,can form a dense rGO/B₄C composite ceramics.At the same time of rGO/B₄C content of rGO composite ceramic performance also has a great influence.When the content of rGO 2.0 vol%,at 1800°C/50 MPa under the condition of the preparation of rGO/B₄C bending strength and fracture toughness of the composite ceramics were as high as 476 MPa and 4.88 MPa·m^1/2,compared with the pure B₄C ceramics increased by 28%and 42%,respectively.Based on the above research results,determined to GO aqueous solution drops gradually to the B₄C/CTAB mixture,the formation of B₄C/GO even the phase-out of coprecipitation mixture.By freeze drying and heat treatment under argon gas protection,can get rGO/B₄C powder mix evenly.