Rare earth is an extremely important strategic resource and plays an irreplaceable role in industrial production. Automobile glass, nuclear magnetic resonance, optical fiber, liquid crystal display, etc. cannot do without the addition of rare earth.Among them, yttrium (Y) is one of the rare earth metal elements and is a gray metal.However, due to its large content in the earth's crust, its price is relatively cheap and it is widely used. It is mainly used in the state of yttrium alloy and yttrium oxide in current social production.Among metal yttrium, yttrium oxide (Y2O3) is the most important yttrium compound. It is insoluble in water and alkali, but soluble in acid. The appearance is white crystalline powder (the crystal structure belongs to the cubic system), and it has very good chemical stability and Low volatility in vacuum, high heat resistance, corrosion resistance, high dielectric, transparency (infrared) and other advantages, so it has been applied in many fields, what are the specific ones?Let's take a look below.

01 Synthesis of yttrium stabilized zirconia powder The following phase transition will occur during the cooling of pure ZrO2 from high temperature to room temperature: cubic phase (c) → tetragonal phase (t) → monoclinic phase (m), in which t will occur at 1150 ° C → m phase transition, accompanied by about 5% volume expansion.However, if the t→m phase transition point of ZrO2 is stabilized to room temperature, so that the t→m phase transition is induced by stress during loading, and a large amount of fracture energy is absorbed due to the volume effect generated by the phase transition, so that the material exhibits abnormal High fracture energy, so that the material exhibits abnormally high fracture toughness, produces phase transformation toughening, and obtains high toughness and high wear resistance.In order to achieve phase change toughening of zirconia, a certain stabilizer must be added and under certain firing conditions, the high-temperature stable phase-tetragonal metastabilizes to room temperature to obtain a tetragonal phase that can change phase at room temperature. This is the stabilizer. Stabilizing effect on zirconia.Y2O3 is the most researched zirconia stabilizer so far. The sintered Y-TZP material has excellent mechanical properties at room temperature, high strength, and good fracture toughness, and the grain size of the material in the collective is small and uniform. So get more attention.02 Sintering aids The sintering of many special ceramics requires the participation of sintering aids. The functions of sintering aids can generally be divided into the following parts: forming a solid solution with the sintered material; preventing crystal transformation; inhibiting grain growth; producing liquid Mutually.For example, in the sintering of alumina, magnesium oxide MgO is often added as a microstructure stabilizer in the sintering process, which can refine the grains, greatly reduce the difference in grain boundary energy, weaken the anisotropy of grain growth, and inhibit Discontinuous grain growth.Because MgO is highly volatile at high temperature, in order to achieve good results, yttrium oxide is often mixed with MgO, and Y2O3 can refine grains and promote sintering densification.03YAG powder synthetic yttrium aluminum garnet (Y3Al5O12) is a man-made compound, no natural minerals, colorless, Mohs hardness can reach 8.5, melting point is 1950 ℃, insoluble in sulfuric acid, hydrochloric acid, nitric acid hydrofluoric acid, etc.The high-temperature solid-phase method is a traditional method for preparing YAG powder. According to the ratio obtained in the binary phase diagram of yttrium oxide and alumina, the two powders are mixed and roasted at high temperature, and the YAG powder is formed through the solid-state reaction between the oxides. body.Under high temperature conditions, in the reaction of alumina and yttrium oxide, the mesophase YAM and YAP will be formed first, and finally YAG will be formed.