Hard and tough boron suboxide based composites

Boron Suboxide (B6O) powder was synthesized at temperatures of about 1400 oC from the reaction of boron and boric acid powders. The synthesized B6O powders were hot pressed at 1900 oC and at pressures of 50 MPa. Additionally to pure B6O materials, composites with Aluminum were prepared. The microstructure and properties of the sintered compacts were investigated. The addition of Aluminum in the composites results in the formation of an additional Aluminum Borate phase. The composites showed a similar hardness (~30GPa) as the pure B6O samples but an increased fracture toughness (~3.5MPa.m1/2).