Investigation Into SiB6 Effects On The Microstructre And Mechanical Properties Of B4C

Because of their excellent properties such as extremely high hardness, wear resistance, low specific weight, high cross section for neutron absorption and resistance to chemical attacks, boron carbide based ceramics have great potential for industrial applications such as armor sheets, rocket nozzles, cutting tools, high temperature resistant coating, neutron-absorbing materials, etc. In spite of its unique properties, boron carbide has some disadvantages like relatively low strength (200-400MPa), low sinterability and low fracture toughness which have restricted its applications. Due to the presence of strong covalent bond and low diffusion rate, densification of boron carbide above 80% of theoretical density is very difficult. To reduce these problems, a number of secondary phases were added to B4C as sintering aids. It this paper, the effect of SiB6 additive on the sintering behavior and mechanical properties of boron carbide was investigated. It was found that the addition of 0-10% of SiB6 to B4C led to a remarkable improvement in the sinterability and density of boron carbide. The maximum theoretical density of 98% was obtained by 5% SiB6 addition. The mechanical properties such as microhardness, bending strength and fracture toughness were also increased with SiB6 increasing up to 5%. As the amount of SiB6 was increased further, the mechanical properties were reduced.