Ordinary Pressure Sintering Method Prepare Tungsten Trioxide Ceramics

Tungsten trioxide (WO₃) is a kind of extremely important high-tech materials, it has great potential in many areas of chemical, energy, electric power etc.

The common sintering processes of ceramics include ordinary pressure sintering method, atmospheric pressure sintering method, reaction sintering method and hot press sintering method. Ordinary pressure sintering is sintered under the usual air atmosphere and atmospheric pressure, without special pressure requirements.

Weighing directly the tungsten trioxide powder, adding certain deionized water and cemented carbide ball to mesh screening in a plastic cylinder after wet drying, prepared nanoscale powder sample. Take a certain amount of tungsten trioxide powder that has been good milling, pressing the powder through powder pressing machine. Calculate the pressure and press the blank according to the size of the blank, control the pressure and the pressure protection time. Prolonging the pressure time is beneficial to reducing the stomatal rate. It is beneficial to the discharge of air and pressure in the blank to improve the density and density uniformity of the blank. The press blank is put into the furnace to be sintered in the furnace. The sintering temperature is positioned at about 1100-1200°C, and the temperature, heat preservation and cooling time are set.

At 500-600°C, there are certain tungsten trioxide micro expansion, at 700°C it began to shrink. When it shrink at 1100°C, the it basically stopped and the contraction is not obvious. Later it appears round angle at 1200°C, at 1240°C WO₃ began to melt. 1200°C is an ideal sintering ceramics temperature, the temperature is too high will occur over burning or melting.

It is unrealistic to simply prolong the sintering time to improve the properties of the material, and time is not the most important and key variable in the densification process.

Tungsten oxide is a brittle material, and high molding pressure can easily cause brittle fracture of tungsten oxide and affect its final properties. The molding pressure of repeated experiments is best at 4-5MPa.

Therefore, the preparation of WO₃ ceramics heating, cooling time of the parameter setting is 1200°C, holding an hour by ordinary pressure sintering method in 4-5MPa.

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