Liquid phase assisted hot pressing of boron suboxide-materials

Boron suboxide materials with Co sintering additives

“…The starting B 6 O powder was prepared by the reaction of B with B 2 O 3 as described elsewhere [10,16,20]. The powder produced was jet milled up to a grain size of 2.5 mm and then attrition milled for 30 h with 2.5 mm steel balls at a speed of 200 rpm.…”

“…The resulting sintered materials had improved fracture toughness (3-5 MPa m 1/2 ) and only a slight reduction in Vickers microhardness (31 GPa under 500 g load) in comparison to pure B 6 O materials (34 GPa) [16][17][18]23,26]. The investigation of the microstructure reveals that the material was densified predominantly by liquid phase sintering.…”

Liquid phase assisted densification of superhard B6O materials

“…11 Recently we could show that B 6 O materials with the addition of Al 2 O 3 can be hot pressed at 1900 • C. The resulting materials have improved fracture toughness and only a slight reduction in hardness in comparison to pure B 6 O materials. [12][13][14] Microstructural analysis showed that aluminium borate is formed at the grain boundaries beside micropores. The investigation of the microstructure reveals that the material was densified, at least predominantly, by liquid phase sintering.…”

Synthesis of B₆O powder and spark plasma sintering of B₆O and B₆O–B₄C ceramics

“…In addition, as-received raw B 4 C powder always contains graphite and boron oxides. 38) Andrews et al's 30) thermodynamic calculations showed that, at low temperatures, carbon is in equilibrium with B 6 O and reacts with B 2 O 3 to form B 6 O:…”

“…Therefore, the reaction takes place only after the decomposition of B 2 O 3 . 30) In addition, the reaction between B 2 O 3 and B 4 C can occur:…”