Effect of activated carbon additive on microstructure and phase composition of reaction bonded boron carbide ceramic

 Boron carbide is highly regarded because of many properties such as high hardness, high Young’s modulus, low density and etc. however, application of B4C is rather limited due to difficulties in densification and low fracture toughness. In this research, uniaxial press at constant pressure of 140 MPa was applied to fabrication of boron carbide porous preforms. B4C powder with size of 43µm, activated carbon with the amount of 0,5,10 Wt.% and phenolic resin powder as a binder and Porosity-causing agent with the amount of 9 Wt.%, were used as raw materials. Infiltration operation with molten silicon had performed in vacuum furnace in temperature 1600 °C. β-SiC phase produced from silicon and carbon that caused the volume density and strength properties of specimens during infiltration process. Residual silicon was decreased from 35%.vol to 18 vol.% with increasing activated carbon contents, on the contrary, secondary silicon carbide had increasing continuously from 10%.vol to 2 vol.%. Decreasing in residual silicon and increasing in β-SiC phase determined by Image analysis software.