Method for preparing high-density fused quartz ceramic

Abstract

The invention provides a method for preparing a high-density fused quartz ceramic, belonging to the field of ceramic materials. The method comprises the following steps of: catalyzing ethyl orthosilicate to be hydrolyzed to generate silica solution by controlling a hydrolysis condition, coating homogeneous sol on the surface of ultrasonically-dispersed fused quartz powder, controlling a coating technology to obtain the well-coated fused quartz ceramic powder, filtering, drying, levigating, and calcining to obtain the coated powder for pressing and sintering. The dense fused quartz ceramic is prepared by a pressing and sintering technology, the sintering can be promoted due to the high activity of the silica solution in the process of sintering, and the density can be improved. The density of the prepared fused quartz ceramic is more than 98%, the room-temperature bending strength is more than 60MPa, and the phenomenon of devitrification can be avoided. The method provided by the invention is simple in technology and low in energy consumption, raw materials are easy to obtain and low in cost, and the method can be used for preparing the high-performance fused quartz ceramic.

Description

technical field [0001] The invention relates to the technical field of powder metallurgy and belongs to the category of ceramic materials. In particular, it provides a method of using homogeneous sol to modify the surface of powder, and then preparing high-density fused quartz ceramics through calcining, pressing and sintering processes. technical background [0002] Due to a series of excellent properties such as excellent thermal shock stability, low thermal conductivity and low thermal expansion coefficient, fused silica ceramics have been more and more widely used in metallurgy, glass, chemical industry, aerospace and other fields. At home and abroad, great efforts have been invested in the research of fused silica ceramics. [0003] Fused silica ceramics have a series of excellent properties such as good thermal stability, small thermal expansion coefficient, low dielectric constant, good acid and alkali corrosion resistance, good electrical insulation, and low cost. ...

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Problems solved by technology

[0006] Although quartz ceramics have the above-mentioned excellent characteristics, compared with other structural ceramics, their strength is significantly lower. This is mainly due to the lower temperature of cristobalite crystallization and crystallization of fused quartz, the main raw material for producing fused quartz ceramics. The firing temperature of fused silica ceramics is controlled below 1200°C, and this temperature is very unfavorable to the sintering of materials

In order to improve the low-temperature sintering performance of quartz ceramics and prepare dense fused silica ceramic materials, it is usually an effective method to add sintering aids. The study found that sintering aids (H 3 BO 3 、H 3 PO 4 、Si 3 N 4 , Y 2 o 3 ) can promote the sintering of fused silica ceramics within a certain range, but the addition of sintering aids also promotes the crystallization of fused silica, and with the increase of the content of sintering aids, the crystallization is more serious, and the thermal expansion coefficient of the addition is the same as Fused silica cannot be matched, which will lead to a decrease in the thermal stability of the material and damage during use

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