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Physical and chemical properties and application fields of zirconium dioxide

wallpapers Tech 2020-07-14
Zirconium dioxide (chemical formula: ZrO2) is the primary oxide of zirconium. It is usually white, odourless and odourless crystals, and is difficult to dissolve in water, hydrochloric acid and dilute sulfuric acid. Usually contains a small amount of hafnium dioxide. The chemical properties are inactive, and it has the characteristics of high melting point, high resistivity, high refractive index and low coefficient of thermal expansion, making it an essential high-temperature resistant material, ceramic insulating material and ceramic sunscreen. It is also the primary raw material for artificial drilling. The bandgap is about 5-7eV.

Physical properties

Characters: White heavy amorphous powder. Odourless. Tasteless. Soluble in 2 parts sulfuric acid and 1 part In the mixed solution of water, it is slightly soluble in hydrochloric acid and nitric acid, slowly soluble in hydrofluoric acid, and almost insoluble in water. Irritating. The relative density is 5.85. Melting point 2680 ℃. The boiling point is 4300 ℃. Hardness is inferior to diamond.

Molecular structure: monoclinic system at low temperature, forming a tetragonal crystal form above 1100°C and a cubic crystal form above 1900°C.

Chemical properties

1. The zirconium dioxide obtained from burning zirconium dioxide hydrate or volatile oxyacid zirconium salt is a white powder, insoluble in water

2. The zirconium dioxide captured by light burning is relatively easy to be dissolved by inorganic acid. The zirconium dioxide captured by intense heat burning is only soluble in concentrated sulfuric acid and hydrofluoric acid, and the zirconium dioxide after melt recrystallization only reacts with hydrofluoric acid;

3. Zirconium dioxide is an amphoteric oxide, which can form zirconate by co-melting with alkali, but [2] but zirconate is readily hydrolyzed to ZrO2·xH2O and precipitated in water.

4. Zirconium dioxide reacts with carbon and chlorine at high temperature, or acts with carbon tetrachloride to produce zirconium tetrachloride and zirconium oxychloride, and hydrolyzes to obtain zirconium dioxide.

5. It interacts with carbon in the arc to form zirconium carbide.

6. ZrO2 in oblique zircon type is yellow or brown monochromatic slanted crystal. It is insoluble in water, hydrochloric acid and dilutes sulfuric acid, but soluble in hot concentrated hydrofluoric acid, nitric acid and sulfuric acid. Eutectic with alkali to produce zirconate. The chemical properties are very stable. Used for making high-grade ceramics, enamel and refractory materials. It can be prepared by co-melting zircon and soda ash, leaching sodium zirconium with water, reacting with hydrochloric acid to form zirconium oxychloride, and then calcining.

Application field

Raw materials for metal zirconium and its compounds

They are used for making metal zirconium and zirconium compounds, making refractory bricks and crucibles, high-frequency ceramics, abrasive materials, ceramic pigments and zirconate, etc. and mainly used for piezoelectric ceramic products, daily ceramics, refractory materials and precious metal smelting Zirconium brick, zirconium tube, the crucible, etc. It is also used to produce steel and non-ferrous metals, optical glass and zirconium dioxide fibre. It is also used for ceramic pigments, electrostatic paints and baking paints. Used in the epoxy resin can increase the corrosion of heat-resistant saltwater.

Refractories

Zirconia fibre is a polycrystalline refractory fibre material. Due to the high melting point, non-oxidation and other high-temperature characteristics of ZrO2 itself, ZrO2 thread has a higher service temperature than different refractory fibre varieties such as alumina fibre, mullite fibre, aluminium silicate fibre and so on. The zirconia fibre is used for a long time under an ultra-high temperature oxidizing atmosphere above 1500 ℃. The maximum operating temperature is up to 2200 ℃, and even to 2500 ℃, it can still maintain the complete fibre shape. The high-temperature chemical stability, corrosion resistance, oxidation resistance, thermal shock resistance, Non-volatile and non-polluting, it is the most advanced refractory fibre material in the world. The strength of ZrO2 to acid and alkali corrosion is much more muscular than that of SiO2 and Al2O3. Insoluble in water, soluble in sulfuric acid and hydrofluoric acid; slightly soluble in hydrochloric acid and nitric acid. Can be eutectic with alkali to generate zirconate.

Gas turbine

The application of plasma-sprayed zirconium dioxide thermal barrier coatings in aviation and industrial gas turbines has made significant progress. It has been used in the turbine part of gas turbines within specified limits. Because this coating can reduce the temperature of air-cooled high-temperature parts by 50~200 ℃, it can significantly improve the durability of high-temperature components, or allow the increase of gas temperature or reduce the amount of cooling gas required to maintain the temperature of high-temperature components. To improve the efficiency of the engine. 

Ceramic material

Because zirconia has a broad refractive index, high melting point, and strong corrosion-resistance, it is used as a raw material in the kiln industry. Piezoelectric ceramic products include filters, loudspeaker ultrasonic underwater sound detectors, etc. There are also daily-use ceramics (industrial ceramic glaze), zirconium bricks and zirconium tubes for precious smelting metals. Nano zirconia can also be used as a matrix material for polishing agents, abrasive particles, piezoelectric ceramics, precision ceramics, ceramic glazes and high-temperature pigments.

other

Also, zirconia can be used in the manufacture of incandescent gas lampshades, enamel, white glass, refractory crucibles, etc. X-ray photography. Abrasive materials. They are used together with yttrium to manufacture light source lamps in infrared spectrometers, thick film circuit capacitor materials, and piezoelectric crystal transducer formulations.

Preparation process

Stabilized zirconia for industrial refractories is mostly made by electrofusion. Stabilized zirconia can be prepared by adding carbon and stabilizer calcium oxide during the zircon fused process. At the same time, it is removing silicon, zirconia and calcium oxide act as a reliable solution, which is then crushed and sized. The stabilized and partially stabilized zirconia used in fine ceramics is generally made by the wet method. At present, the most mature and commonly used is the neutralization precipitation method, the preparation process is shown in the figure. Dissolve the purified zirconium oxychloride with pure water, filter to remove insoluble, adjust the zirconium concentration in the solution, and add the required amount of yttrium chloride solution (or other rare earth metal or alkaline earth metal chloride solution), then add ammonia Neutralize the precipitate. After washing the precipitate with hot water, it is then filtered, dried and calcined. The calcined product can be crushed to obtain ultrafine stable zirconia powder.

Partially stabilized zirconia is made by controlling the amount of stabilizer added so that it is not sufficient to achieve complete stability. Somewhat stabilized zirconia has high strength and thermal shock resistance and has a wide range of uses in structural ceramics.

Trunnano is one of the world's largest manufacturers of zirconium dioxide. There are various sizes of zirconium dioxide products. If necessary, please contact Dr Leo, email: brad@ihpa.net.

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Tag: Zirconium dioxide   Trunnano   ZrO2