Y2O3·ZrO2 (YSZ) Powder Preparation Method

Y2O3·ZrO2 (YSZ) powder Preparation Method is a high melting point metal oxide with very stable chemical properties and features such as wear resistance, high-temperature resistance, and corrosion resistance. Zirconia can be widely used as a new structural and functional ceramic material in many fields due to its excellent mechanical properties such as good thermal shock resistance, high refractive index,x, and good thermal stability.

All ceramic materials have a fatal flaw, which is insufficient toughness. Stabilizers or other methods are needed to improve their toughness. Adding stabilizers to form stabilized zirconia is one of the most commonly used methods. Among the stabilizers, Y2O3·ZrO2 (YSZ) powder has the best stabilizing effect and is also the most commonly used.

What are the preparation methods of Y2O3·ZrO2 (YSZ) powder?

Coprecipitation

The method of adding a precipitant to a solution containing multiple cations and precipitating all ions at the same time is called coprecipitation. Generally, alkaline substances such as ammonia water, caustic soda, (NH4)2CO3, or urea are added to a mixed aqueous solution of soluble zirconium salt and yttrium salt to generate hydroxide precipitates of zirconium and yttrium. The precipitate is then washed, dried, heat treated, and crushed to obtain ultrafine powder. This method is not only simple in process, has low requirements on equipment, low cost, and good repeatability, but it also can produce oxide powders of various crystal forms, with a minimum particle size of up to tens of nanometers, good chemical uniformity, easy sintering, and high purity, which is suitable for both laboratory scale and industrial scale production.

Sol-Gel method

The basic principle is as follows: use precursors such as alkoxy metals or metal salts and co-solvents of organic polymers to hydrolyze and condense the precursors in the co-solvent containing the polymer, control reasonable conditions so that the polymer does not phase separate during gel formation and drying, and nanoparticles can be obtained.

Coprecipitation-gel method

This method uses zirconium oxychloride and yttrium chloride as raw materials, adds organic dispersants and inorganic dispersants to the solution, adds ammonia water dropwise under heating conditions to form a coprecipitate, and then undergoes gelation. This method mainly uses cheap raw materials for precipitation.

Alcohol-water solution method

This method is a relatively new method for preparing nano ZrO2 powder. Its basic principle is that when the ZrOCl2 alcohol-water solution is heated, the dielectric constant of the solution decreases rapidly, resulting in a decrease in the solvation ability of the solution and the solubility of the solvent, and the solution reaches an oversaturated state and produces precipitation.

Hydrothermal method

It is a chemical reaction under certain hydrothermal conditions in an autoclave to achieve atomic and molecular level particle construction and crystal growth. There are many ways to prepare ZrO2 powder under hydrothermal conditions, mainly: hydrothermal precipitation, hydrothermal crystallization, hydrothermal oxidation, hydrothermal synthesis, hydrothermal decomposition, hydrothermal anodic oxidation, hydrothermal dehydration, etc. Among them, hydrothermal precipitation is the most commonly used method.

The biggest advantage of the hydrothermal method is that it can directly obtain crystalline oxides from a water medium at about 200°C, avoiding the high-temperature calcination process and effectively preventing powder agglomeration.

Microemulsion method

Recently, the microemulsion method has attracted wide attention because it not only has a simple experimental device, easy operation, and good dispersion performance, but also the microemulsion structure fundamentally limits the particle growth, can artificially control the size of the synthesized particles, and has a narrow particle size distribution. The obtained particles are spherical and have unparalleled advantages over other chemical methods in the preparation of ultrafine particles, especially nano-scale particles. It is an ideal reaction medium for the preparation of ultrafine particles, but the production process is complicated and the cost is high.

Self-propagating method

The self-propagating method is also a relatively new method, which uses the self-heating and self-conduction effect of the high chemical reaction heat between reactants to synthesize materials. Its main feature is that the reaction only needs local ignition to trigger the combustion wave and make it propagate in the raw materials to realize the systematic synthesis process. This method has a short reaction time, low pollution can prepare small-sized grains, and the raw materials are cheap. The molar ratio is easy to control during the preparation process, but the particles obtained by this method are unevenly distributed and agglomerated.