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How to control the hydrogen and nitrogen content of zinc alloy die castings

How to control the hydrogen and nitrogen content of zinc alloy die castings

In the production of high-end zinc alloy die castings, a certain percentage of product defects often occur, as well as unexpected product price increases. Therefore, it is ensured that the incidence of pores and shrinkage cavities is the lowest, and the defects are reduced as soon as possible and solved.

As long as the furnace is operated under normal parameters, it is easy to understand the relationship between the gas in the molten pool space, the molten liquid and its surrounding environment. Liquid metals are very active, forming compounds on their surfaces. The basic principle is that the equilibrium of the three is destroyed, and they are in a state of equilibrium with the surrounding liquid. The effect between the content and the surface of the melt. It is concluded that the formation of pores is closely related to liquid zinc and solidification.

When the content of hydrogen and nitrogen in liquid zinc is too high, pinholes will form in the zinc alloy die casting. The reason of pinholes precipitation in the solidified zinc alloy die casting is due to the decrease of gas solubility during solidification. The gas content in the molten liquid varies with the temperature of the molten liquid and the treatment method. This change is also reflected in the filling process of liquid zinc. The hydrogen and nitrogen generated by the reaction at the cavity interface are released from the molding materials and can also be melted into the liquid zinc, which is very interesting. From melting to pouring, and then to cavity filling. In each stage of the production chain, the change of equilibrium parameters reflects the change of gas content (including hydrogen and nitrogen).

The melting process does not appear to be caused by the chaos of extreme value and control of hydrogen. What is important is that the change of hydrogen and nitrogen is mainly the melting process. The influence of temperature and zinc tank is small. The contents of hydrogen and nitrogen are also affected by casting. Before the gas content in liquid zinc is poured into the mold, there is a difference between them, which affects the quality of the product.

The molten zinc in cupola contains more nitrogen and less hydrogen than that in induction furnace. The preheating of charge will be lower than that of induction furnace (hydrogen content), but their content is not always lower than that of cupola zinc water. Both hydrogen and nitrogen increase during mold filling, and hydrogen content increases more strongly.

The liquid zinc does not work until it enters the mold. The same work should also include the turbulence in the mold filling process, the formation and occurrence of gas in the solidification process, and part of the work should also be placed in various conditions to absorb gas in the mold. In order to obtain the information and structure of solidification process of cast zinc.


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