Spark plasma sintering of ZrB2 using Al3BC3 as an additive

Abstract

The low-temperature sintering of zirconium diboride (ZrB2) using aluminum borocarbide (Al3BC3) as an additive was studied. To improve the densification of ZrB2, the SPEX milling process, spark plasma sintering and Al3BC3 additive was used. Amorphous phases of the Al-O system were formed as secondary phases in the sintered specimen, and the amount of those phases increased markedly when the Al3BC3 content was more than 3 wt%. These amorphous phases enhanced the densification due to filling in the pores during sintering. Also the Al3BC3 additive could promote the densification of ZrB2 by removing oxide impurities such as ZrO2 and B2O3 through an aluminothermic reaction. The relative density, hardness and fracture toughness of sintered ZrB2 with 5 wt% Al3BC3 at 1700 degrees C under 60 MPa pressure were 99.9%, 20.04 GPa and 3.37 MPa.m(0.5), respectively.