Tungsten Trioxide Ceramic Doping Object

Tungsten trioxide is a common metal ceramics, metal ceramics with low density, high hardness, wear resistance, thermal conductivity, both the advantages of ceramics and metals, metal ceramics both ductile metals, high heat resistance and good thermal conductivity stability, but also has ceramic high temperature, corrosion and wear-resistant features. Tungsten oxide ceramics not only has the general characteristics of the cermet also has a pressure-sensitive characteristics, the researchers in order to improve the pressure-sensitive properties of tungsten trioxide ceramic, generally choose the way doping suitable dopant added to the fine ceramic varistor characteristics The form has played a key role.

Varistor under normal circumstances would be to add a doping element to the following three main purpose:
(1) ceramic sintered tungsten trioxide poor performance, doped tungsten trioxide way alter the ceramic sintering process, to help sintering purpose without doping ceramics sintered tungsten trioxide can densification. For example, low melting point metal oxide in a liquid phase process capable of forming tungsten trioxide to tungsten in the ceramic sintered tungsten trioxide promote densification of the ceramic.

(2) The reason why the presence of tungsten oxide ceramic varistor characteristic, because the internal and external surfaces of the grains have different defects, such that different internal and external resistivity, indirect control defect types of elements, doping and other species by controlling the doping and distribution of defects on the pressure-sensitive properties of its essential.

(3) capable of controlling the situation doping element grain growth, adjust the size of the varistor voltage. Bi, Co, Sb and Pr and other transition metals are able to significantly improve the performance of the ceramic junction burn doping elements and the pressure-sensitive properties.
 
Doped Bi2O3 and Pr6O11 can effectively improve the sintering properties of tungsten trioxide but in order to achieve high density and pressure-sensitive properties of tungsten trioxide fine ceramics, on the basis of its needs, and look for suitable doping elements to improve trioxide Tungsten ceramic varistor properties.

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