Effect of additives introduced by ball milling on sintering behavior and mechanical properties of hot-pressed B4C ceramics

The ball-milling process is a usual route employed to break up agglomerates in the powder or mix the powder with additives when preparing ceramics. Although it is well known that a powder can be “contaminated” by the wear particles from the milling balls, the study dealing with how the preparation and properties of a hard material would be affected by additives just introduced by scrape of milling balls has been scarce. In the present work, sintering behavior and mechanical properties of hot-pressed B4C with additives derived from milling balls were investigated. Polyoxymethylene, ZrO2, Al2O3 and Si3N4 were selected as different ball materials. The results show that the sinterability of B4C could be significantly enhanced because of the incorporation of one of these additives, i.e. ZrO2, Al2O3 and Si3N4 (approximately 3–6 vol%). As a result of improvement in density, excellent mechanical properties of B4C ceramics were obtained. Among them a flexural strength of B4C added by ZrO2 reached 630 MPa.