1. Zirconia Oxide Pyrolysis Method: Zircon and caustic soda are melted at 650℃. The melt is leached with hot water, and silicon separates from sodium zirconate in the form of sodium silicate. Treatment with sulfuric acid yields a zirconium sulfate solution. After further impurity removal, ammonia is added to precipitate zirconium hydroxide. Hydrochloric acid is added to dissolve the zirconium hydroxide, yielding zirconium oxychloride. This solution is then evaporated, concentrated, cooled, crystallized, pulverized, and calcined to obtain the finished zirconium dioxide. Alternatively, easily purified zirconium compounds can be thermally or oxidatively decomposed to prepare high-purity zirconium oxide.
2. Colloidal Method: Silica sol is added to a zirconium oxide solution to form a colloidal solution. This solution is then formed by blowing and drawing, dried, and sintered into fibers.
3. Extrusion Method: Zirconia sol or zirconium oxide particles and a thickener are mixed to form a blank. The blank is extruded from a die using hydraulic pressure or a screw extruder to form fine filaments, which are then sintered and solidified to form fibers. Fibers produced by this method are relatively coarse and have lower strength.
4. Impregnation Method: Viscose fibers or the entire fabric are first immersed in a zirconium hydroxide solution for an extended period, causing the viscose fibers to swell. Then, through pyrolysis and calcination, zirconium oxide fibers with a certain tensile strength are obtained.
5. Hydrolysis Method: High-purity ultrafine zirconium dioxide is prepared by hydrolyzing zirconium oxychloride. A 0.2–0.3 mol/L high-purity zirconium oxychloride solution is added to deionized water for hydrolysis. The zirconium oxychloride solution is boiled for an extended period, allowing the hydrogen chloride generated during hydrolysis to continuously evaporate and be removed. The hydrolysis reaction is carried out at boiling for more than 50 hours. After filtration, the product is washed with deionized water, dried, calcined, and pulverized to obtain the final product.
6. High-Temperature Hydrolysis Method: A 1 mol/L high-purity zirconium oxychloride solution is sprayed into a decomposition furnace at 1000 °C. The tiny zirconium oxychloride droplets first undergo water evaporation, then hydrolyze to form zirconium dioxide. The decomposed zirconium dioxide is collected by a cyclone separator, then acid-washed, washed with water, and dried to obtain the final product.
7. Sol-gel method: Alcohol and water are added to zirconium alcohol [ZrO(C3H7)4], followed by a catalyst. After thorough mixing, decomposition begins. The mixture is allowed to gel and form a viscous liquid. A suitable viscosity is selected, and the mixture is dried and then heated to 500-1000 °C for high-temperature fibrosis and calcination to obtain the product.
8. Alkyl salt hydrolysis method: High-purity ultrafine zirconium dioxide is prepared using zirconium tetrachloride, ammonia, and propanol as raw materials. In the presence of benzene solvent, high-purity zirconium tetrachloride, propanol, and ammonia are reacted at 5 °C to obtain zirconium alkoxide. Ammonium chloride is removed by filtration, followed by hydrolysis precipitation, filtration, drying at at least 100 °C, calcination, and pulverization to obtain the product. The hydrolysis conditions directly affect the particle size, shape, and aggregation of the product. This method can produce ZrO2 with uniform particle size and shape and a single structural phase.
9. Zirconium oxychloride (ZrCl2O·8H2O) is recrystallized with hydrochloric acid or methanol and calcined at high temperature to obtain the finished product.
10. Zirconium tetraalkoxy is purified by distillation, and its vapor decomposes at 350-500 °C to obtain the final product.
11. Zirconium tetrachloride is purified by distillation, and its vapor reacts with excess oxygen at 1200 °C to obtain zirconium dioxide.
