Technical solution for enhancing toughness and improving density of boron carbide ceramics
At present, the main method for enhancing the toughness of boron carbide ceramics is to optimize the material composition, such as by increasing fiber/whisker toughening and second phase particle toughening. Second phase particle toughening is achieved by adding metal phases, transition metal borides, graphene, nanoparticles, rare earth compounds, etc., and changing the internal crystal structure of ceramics, such as controlling the microstructure of ceramics, reducing the particle size of grains, increasing the density of ceramics, and forming a layered structure of ceramics.
The first solution is for technicians to toughen boron carbide ceramics by adding carbon fibers. The toughening effect is most significant when the volume of carbon fibers reaches 10%. The fracture toughness of CF/B4C composite material is increased by 12%, reaching 4.29 MPa · m1/2.
The second solution is to add silicon carbide whiskers to B4C Si composite ceramics, and it was found that the toughness of boron carbide ceramics was enhanced. The best effect was achieved when the addition amount was 10%, and the fracture toughness was increased by 35%, reaching 5.77 MPa · m1/2.
The third option is to use anhydrous ethanol reagent, and after deoxygenation treatment, the particle size of B4C ceramic crystals is reduced. After deoxygenation of 15wt% boron powder, the sample is hot pressed and sintered at 2100 ℃, and the fracture toughness of the obtained sample is increased by 13% compared to before deoxygenation, reaching 3.93MPa · m1/2.
The fourth option is to introduce Ti3SiC2 into B4C to make composite materials. As the content of Ti3SiC2 increases, the toughness of B4C also increases. When the content of i3SiC2 reaches 25-30%, the toughness of the composite material reaches 6.54 MPa · m1/2.
Through the above four methods, researchers and technicians have improved the toughness of boron carbide ceramics and prepared boron carbide ceramics with a product density of 2.52g/cm3 through pressureless sintering process.