Synthesis and characterization of ultrafine zircon powder

Abstract

The synthesis of ultrafine zircon (ZrSiO 4) powder with high purity was studied by using ZrOCl 2 solution and fumed SiO 2 as starting materials. The zircon precursor gels which were obtained by a wet chemical precipitation were seeded with zircon sand powder. The influences of processing, seed content and calcination temperature on the synthesis of zircon powder were investigated by XRD, TEM and IR spectroscopy etc. It was found that the washing of seeded gels by ethanol greatly benefited the formation of zircon at lower temperatures. Single-phase zircon powder can be obtained from the precursor gel seeded by 3 mol% zircon sand particles when calcined at 1400 °C for 2 h with primary particle size of 0.2–0.3 μm and impurities content of less than 0.2 wt%. The mechanism of zircon formation is heterogeneous nucleation due to the existence of zircon seeds. The relative density of hot-pressed sintered zircon at 1600 °C for 1h reaches 99.1% theoretical and its flexural strength and fracture toughness at room temperature are 320 ± 15 MPa and 3.0 ± 0.4 Mpa · m 1 2 , respectively.