The Effect of Surface Oxides During Hot Pressing of TiB ₂

Abstract

Hot pressing of TiB 2 has been investigated with particular emphasis on the evolution of secondary phases originating from the initial surface oxide layer on the TiB 2 powders. Carbothermal reduction of the surface oxides during sintering was also investigated by adding carbon to the TiB 2 powder. TiO 1− x C x was shown to be the main secondary phase in hot‐pressed TiB 2 , and carbon was shown to strongly influence on sintering process and the amount, composition and distribution of the secondary phase TiO 1− x C x . The formation of TiO 1− x C x is discussed in relation to volatile boron oxide, which reacts with the graphite die to produce CO gas, which further may cause transport of carbon into TiB 2 during sintering before pore closure. Finally it was demonstrated that the density could be controlled by addition of carbon to the TiB 2 powder.