technical process for alumina piezo ceramics

Views: 5 Author: Site Editor Publish Time: 2018-08-31 Origin: Site

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The preparation process of alumina piezo ceramics mainly includes three aspects: preparation of alumina powder, formation of alumina ceramics and preparation of sintered alumina ceramics. At present, the preparation process of the alumina powder includes following aspects:

(1) an hydrolysis method. The method is characterized under the action of a catalyst, aluminum and an organic alcohol are reacted to form an aluminum alcohol solution, which is hydrolyzed to form aluminum hydroxide, and the aluminum hydroxide is sintered at a high temperature to obtain a high purity alumina powder.

(2) Crystallization method including aluminum carbonate crystal crystallization method and aluminum sulfate according to crystallization method. Among them, the aluminum carbonate is calcined at a temperature of 1200°C to obtain a high purity alumina according to the crystallization method; the aluminum sulfate is thoroughly mixed with the aluminum sulfate according to the crystallization method. The aluminum piezoelectric material piezoceramic cylinder tubes crystal is prepared, and the crystallization process of the aluminum sulfate money is controlled to increase the purity of the aluminum sulfate. The crystals were thoroughly calcined in a muffle furnace at 1200°C. The method removes impurities such as silicon and iron from the sodium aluminate solution to obtain high-purity aluminum hydroxide, and obtains high-purity alumina by calcination or the like. The high purity sodium aluminate solution was subjected to deep desiliconization, and the optimum process parameters for the removal of silicon from the sodium aluminate solution were analyzed.

(3) Aluminum hydroxide sintering method. Industrial aluminum hydroxide containing Si, Fe impurities was placed at 500 °C for 1.5 h, and then acid-dissolved and washed with water to continue sintering to 900 °C to obtain high-purity ultrafine alumina which is having a purity of 99.95%.

(4) A gas phase synthesis method of A1C13. The method is to place A1C13 at 200 °C in the presence of a catalyst.

The forming process of Pzt material piezoceramic tube transducer mainly includes dry pressing, grouting, extrusion molding and casting molding. Among them, the casting method is relatively new compared with the thousand-layer piezo ceramic molding method, and is an important molding process for the thin-film ceramic material. A solvent, a dispersant, a binder, a plasticizer and the are added to the piezo ceramic powder to obtain a uniform dispersed slurry, and then a molding method of a piezo ceramic sheet having a requiring thickness is prepared on a casting machine. The casting process mainly includes aspects:

(1) a non-water-based tape casting process. The non-water-based casting method was used to prepare the piezoelectric ceramic sensor substrate. The influence of the non-water-based casting process parameters on the performance of the substrate was discussed. The optimum ratio of the non-water-based casting molding additive was analyzed. The sintering obtained an alumina piezo ceramic substrate which is having the piezo crystal grains, high density, and good dielectric properties.

(2) tape casting molding process. alumina piezo ceramic substrates with a smooth surface and a relative density of up to 99.5% was prepared by casting method. The effect of pH and dispersant on alumina slurry was studied. Plasticizer and bonding were studied. The effect of the amount is on the caster blank and its sintering properties.

Sintering enables the piezo ceramic sensor material to achieve the desiring microstructure and is an important process for imparting various properties of the material. The preparation process of the sintered alumina includes the hot press sintering, which applies a unidirectional axial force in the high temperature sintering environment to make the sintering body fully densified. The powder was subjected to hot press sintering at 1450°C to prepare a fine alumina piezo ceramic material which is having a grain size of 0.5 m and a flexural strength of 445-545 MPa. When Mg0 was added for further study, alumina piezo ceramics with a relative density of 99.3% and a flexural strength of 635 MPa were prepared under the same process conditions. The method is to apply isostatic pressing on the embryo body and sinter, so that the piezoelectric crystals sensor can be sintered at a lower temperature, so that the material which cannot be sintered at normal pressure may be sintered, and sintered into a uniform microstructure and good performance. ceramics. Microwave heating and sintering method utilizes the interaction between the medium and the microwave. In the process of the surface and interior of the piezo ceramic body is simultaneously heated and sintered. The key laboratory of materials department of Tsinghua University studied the microwave sintering technology of tough piezo ceramics, and obtained the relationship between microwave sintering curve and relative density. The mixed gas was subjected to microwave plasma sintering for 15 min to make relative density of the embryo body reach 99% of the theoretical density. The relative density of the piezo ceramics obtained by the conventional sintering method .the same process conditions can only reach 63% of the theoretical density, and the sample is subjected to microwave plasma sintering, and compared with the sample sintered by the conventional furnace.