In the casting process, refractories are often used in ladle, and silica powder, clay and coke powder are usually used in die casting. Silica powder and boric acid are commonly used in steel casting.
Whether in die casting production, or in steel casting production, the use of time is shorter, more frequent knotting and lining, the labor environment is very poor. If it is continuous start-up production, whether pouring ladle or transition ladle, almost every day knot, not more than two days at most, this not only wastes a lot of refractories, but also causes the knotting ladle operators to repeat the same work every day, waste of human and material resources.
Some of these disappeared refractories become slag floating on the surface of the molten metal, and some even become part of the molten metal as the refractory goes into the liquid, because the refractory degree is not enough. With the molten metal pouring into the cavity, the casting slag hole defects are formed.
In order to improve the refractory's refractory, prolong its service life, improve the purity of liquid metal, and ensure the material quality of castings, our company has gradually changed from the original silica-based refractory to the long-term refractory based on alumina, greatly improving the refractory's refractory and prolonging the service life of refractories.
In die casting, the content of alumina in refractories is 45%-90%, and the rest is silicon dioxide. Because there are many kinds of die casting materials, the refractory temperature varies greatly. Therefore, the refractory temperature varies from 1605-1870 C. Different refractories are selected for different die casting materials, and the service life of refractories is also improved from the original daily maintenance. Up to 30 days or more.
This long-acting refractory has been widely used in die casting and steel casting. The content of alumina in the refractory can reach 70%-95%, the content of silicon dioxide can be reduced to less than 15%, and the rest is magnesium oxide. The refractory temperature can reach 1650-1760 C, and the service life of the refractory can be increased correspondingly. More than 5 times.
With the continuous development of refractories, the application of long-lasting refractories has attracted more and more attention in the industry. Standardizing the use of ladle has become a key research object, such as prolonging the lining life, improving the quality of castings, reducing labor intensity, improving comprehensive benefits, and improving the environment.
At present, Dongguan Zinc-Aluminum Alloy Die Casting Plant has basically adopted the above method, that is, Dongguan Zinc Alloy Die Casting can obtain uniform and fine microstructure, the principle is because it makes full use of the role of rapid heating and cyclic treatment, rapid heating, a large number of austenite nuclei, and the emergence of fine grains; The faster the process proceeds, the greater the temperature difference, the better the refinement effect it will get.
Increasing the number of this process, will also get good results, repeated heating and cooling, on the one hand, can promote nucleation, on the other hand, to further refine the nucleated crystal. Every time, the austenite grain is refined once, so that the nucleation rate of the next austenitizing increases.
The hardness and impact value of the sample will increase before cycling in Dongguan Zinc Alloy Die Casting Plant. The results of each cycling treatment are different in Dongguan Zinc Aluminum Alloy Die Casting Plant. The hardness value and impact value will be significantly improved after 3-5 cycles of heat treatment. After Dongguan Zinc-Aluminum Alloy Die Casting Plant, the hardness and impact value of the sample will not change obviously. About 6 times will be close to the detailed boundaries. If Dongguan Zinc Alloy Die Castings are recycled at this time, it is not very helpful to improve the heat treatment efficiency. Therefore, Dongguan Zinc Alloy Die Castings adopt 4-5 cycles as the best.