New Uniformly Porous CaZrO3/MgO Composites with Three-Dimensional Network Structure from Natural Dolomite

Porous CaZrO₃/MgO composites with a uniform three-dimensional (3-D) network structure have been successfully synthesized using reactive sintering of highly pure mixtures of natural dolomite (CaMg(CO₃)₂) and synthesized zirconia powders with LiF additive. Equimolar dolomite and zirconia powders doped with 0.5 wt% LiF were cold isostatically pressed at 200 MPa and sintered at 1100–1400°C for 2 h in air. Through the liquid formation via LiF doping, strong necks were formed between constituent particles before completion of the pyrolysis of dolomite, resulting in the formation of a 3-D network structure. During and after the formation of the network structure, CO₂ was given off to form a homogeneous open-pore structure. The pore-size distribution was very narrow (with pore size ～ 1 μm), and the porosity was controllable (e.g., ～30%–50%) by changing the sintering temperature. The porous composites can be applied as filter materials with good structural stability at high temperatures.