Pressureless reactive sintering of ZrB2 ceramic

Pressureless reactive sintering was investigated to fabricate ZrB2 from a mixture of elemental Zr and B powders. Both hand mixing and high-energy milling were used to blend the powders. The sintering experiments were carried out at 1800, 2000 and 2200 °C. The samples made from the high-energy milled powders had relative densities varying between 66 and 79%, while the relative densities of the hand mixed powders varied between 58 and 70%. The average grain size of the sintered ceramic was independent of the mixing procedure and increased with the sintering temperature (from 8.5 to 23.5 μm for the hand mixed samples and from 4.6 to 34.9 μm for the milled samples).