Problems of graphite mould in nonferrous metal smelting

Graphite mold is mainly used for high temperature resistance. For example, the casting temperature of pure copper is about 1200℃, and the performance of graphite is still stable at this temperature, and the thermal barrier and cold shrinkage are very small, which can be ignored. On the other hand, it has good lubricity, and molten metal is not easy to stick to the mold during solidification. Although the thermal conductivity is poor, it is not necessarily a good thing to have a good cooling effect during casting, so this may become an advantage. Horizontal continuous casting generally adopts graphite mold, because gravity has great influence on solidification and poor lubricity, so it cannot be used for horizontal casting.

The main disadvantage is that it can only be used for 1 to 2 weeks, because molten metal will remain on the mold to some extent, which will affect crystallization and damage the surface quality of ingot. The removed graphite plates need to be repaired, and some high-quality ingots even use new plates in actual production, which is costly. Moreover, at present, high-quality graphite plates cannot be produced in China, and most manufacturers rely on imports, generally Japan and the United States, which are expensive.

At present, there is permanent mold casting in production, but in order to improve lubricity, lubricants such as carbon black and oil are generally added, which are generally only used for vertical semi-continuous casting.

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