Extraction method of zirconia ceramic raw material---spray pyrolysis method

The spray pyrolysis method is the last method of refining zirconia ceramic raw material powder introduced by Kezhong Ceramics Factory. Its advantages and disadvantages are particularly significant. Let's take a look at it together.

The basic principle of the spray pyrolysis method is: spray the mixed salt solution of salt and stabilizer into the high-temperature atmosphere, disperse into countless small droplets, the liquid phase evaporates, and the droplets become smaller, and then the solid phase is precipitated due to supersaturation, and then heated. Decomposition directly generates the required ZrO2 powder. In the process of spray pyrolysis, the atomized small droplets break the powder due to the internal stress generated by the high temperature gradient, so that the prepared powder is loose and has a large specific surface area, but it is difficult to control.

In the pulverization process, in order to obtain nano-powder with fine size, the initial droplet size should be reduced, the surface tension of oil should be reduced, and the droplet density should be limited. Zirconia ceramics generally adopt two manufacturing processes. The first manufacturing process is to stabilize and sinter at the same time. The process is simple and the production cost is low. The disadvantage is that the green body shrinks greatly, and the linear shrinkage can reach 25% to 30%, so the dimensional accuracy of ceramic parts is difficult to guarantee.

The second manufacturing process can ensure the stable quality of the product, and the precise size is small. The disadvantage is that the process is more complicated and the cost is higher. The molding of ZrO2 ceramics is no different from other ceramics. It can be grouted, pressed, extruded and hot-pressed. The grouting-molded Zr(O)2 ceramics is its special feature. When using stable ZrO2 as raw material, the raw material needs to be finely ground to less than 5pm, and the acidic mud with pH=1.3~1.8 is used for grouting.

When monoclinic ZrO2 and stabilizer are used as raw materials, since the mud contains monoclinic ZrO2 and stabilizers (CaO, MgOY2O2), most of the stabilizers are soluble in acid, so only alkaline mud (pH=8~9) can be used. The products formed by alkaline mud grouting are relatively loose. This is because a layer of solvent compound shell is formed on the surface of ZrO2 particles, which causes large shrinkage of the product (up to about 30%) and low body strength.

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