Sol-Gel Powder Synthesis for Fabrication of Zircon-Based Ceramic Composites in a Two-Stage Microreactor

The sol-gel synthesis of zircon, zirconium oxide, and composite powder precursors based on them has been performed in two ways: reverse precipitation and the microreactor method in a two-stage apparatus with intensively swirled reagent flows. A comparison of the synthesis results at all stages is carried out—(1 ‒ x)(H₂SiO₃‒ZrO(OH)₂)‒xZrO(OH)₂ precursor powders, after calcination at 850°С, as well as after sintering powders in the temperature range of 1000‒1300°С. The thermal behavior of the initial nanosized compositions is studied using differential scanning calorimetry and thermogravimetry and dilatometry methods. The temperature coefficients of linear expansion of ceramic samples are estimated. Microhardness values for the (1 – x)ZrSiO₄–xZrO₂ ceramic composites are given with different backgrounds.