The method of production of electrofused zirconium corundum paving brick.

Zirconium fused corundum brick paved with industrial alumina powder and zircon sand is about 66% (including 66% zirconium oxide and silicon dioxide), such as in electric furnace high temperature melting, Canon after melting casting molding, casting temperature of 1780 ~ 1840 ℃), into a model of cooling and the formation of a close to white solid, the petrographic structure composed of zirconium corundum and inclined stone eutectoid and glass phase composition, tell from the reading is zirconium corundum phase and slanting stone eutectoid, between the crystallization of glass phase in them.

When casting process is completed, peripheral, was part of the link model in rapid condensation, but the products is still near the center of the liquid, with the extension of time, the products from outside to inside of solidification thickness increasing gradually, finally complete set. The process of thermal insulation annealing is the process of making products from liquid to solid and gradually eliminating stress. When the product is in a large amount of liquid in the cavity, it has a good auxiliary effect on the composition of the crystal, the shrinkage of the brick solution and the diffusion of the thermal stress. Thermal stress under the liquid is easy to spread, which can reduce products cracking phenomenon, therefore, to extend the time of liquid exist in the model to improve the products volume density, to improve the forming rate is very key factor.

The production methods of the improved zirconia corundum paving bricks are as follows:

1, the type of the group

As shown in figure 2, figure 3, the pattern of conjoined molding combination method, according to the size of the incubator portfolio model quantity, placed from the box together after combination, combination is combined closely with the molding surface and wide width, neat, according to the size of incubator, each fixed combination paving bricks number, according to the combination of the overall specifications set casting riser specifications placed on bricky system model, combined to keep after model, up and down around 200 mm filled the space that the thermal insulation material.

Improved pattern of this way has multiple advantages: first, brick and tile are closely linked, mutual heat transfer, has the best heat preservation effect, the model of a liquid will remain for a longer time, the thermal stress under liquid diffusion release smoothly, reduce products crack; Secondly, the liquid state can be extended to make the molten liquid in the casting mouth more convenient for the brick, so that the volume density is larger and the product quality is better. The third is to speed up the process of casting, assist to prolong the liquid state, and improve the production efficiency.

2. Casting and exhaust.

After completion of melting process in accordance with the prescribed procedures, a one-time heat preservation box for several piece of casting shop and brick, several times due to improved pouring gate, easier to casting, casting speed, casting speed in 25 to 28 kg/s. After casting for 3 min, the first exhaust was broken, and the steel bit was used to break the surface of the casting door, and the steel bit was inserted into one-half of the brick body. Each time interval 3 min, in order to increase the depth of insert brick, repeat three times to complete the exhaust process. The result is that the finished paving brick has no porosity and no porosity, which increases the volume density of the paving brick.

3. Insulation and delivery.

Before moving to the heat preservation area, the insulation layer should be covered not less than 200 mm thick at the top of the casting mouth, and the insulation effect of the casting port and the above position shall be better than that of the lower insulation material. After 8 days of insulation, the surface temperature of the paving brick is about 40.

Heat preservation method is a key step, due to the set of type way forms are connected, the heat transfer of each other can make brick insulation effect is very good, so special attention to the sprue and sprue over parts of the heat preservation effect, to make the sprue liquid within inches long enough, and then to achieve the feeding bricky system requirements. If the heat preservation effect is poor, the molten liquid in the casting mouth will solidify, and it can not give full complement to the molten liquid needed for the brick. In the production of the common paving brick, the brick area collapse, and the loose surface of the cast hole, which is the result of too thin insulation layer or poor insulation effect. From the Angle of comparison, the same holding time for 7 days, after improving the paving brick surface temperature is much higher than change the surface temperature of barnyard grass before paving brick, brick that is improved the time to prolong 1 day to reach the temperature required by the brick.