Brief introduction of die – cast zinc alloys and test methods

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Introduction to the

Die – cast zinc alloy An alloy consisting of zinc as the base and other elements. Commonly added alloying elements are aluminum, copper, magnesium, cadmium, lead, titanium, etc. Zinc alloy has low melting point, good fluidity, easy fusion welding, brazing and plastic processing, corrosion resistance in the atmosphere, and easy recovery and remelting of disabled materials; However, the creep strength is low and the size change is easy to occur due to natural aging. Prepared by melting, die casting or pressure processing. According to the manufacturing process, it can be divided into cast zinc alloy and deformed zinc alloy.

In order to improve economic benefits and seek long-term sustainable development of enterprises, most of the wet zinc smelting plants which mainly produce electrolytic zinc ingot are willing to list the deep processing products of zinc as their product development objects, and most of them are the production of die-casting zinc alloy. Die-casting zinc alloy is Zn-Al-Cu-Mg quaternary alloy.

Due to its low melting point, long mold life, high dimensional accuracy, excellent mechanical properties and easy electroplating, it is widely used as die-casting parts and complex shape castings, and is welcomed by users. At present, the dosage of die-casting zinc alloy in the Pearl River Delta area of our country reaches 200,000 ~ 300,000 t/a, mainly used in the production of toys and auto parts, etc. With the rapid development of automobile, motorcycle industry and construction, household appliances and other industries, the demand of die-casting zinc alloy will grow rapidly.

At present, most of our die-casting zinc alloy is concentrated in the production of metal processing plants and township enterprises, and the scale of the manufacturers is different and scattered. Therefore, it is also an effective supplement to the market to provide die-casting zinc alloy products for zinc smelting enterprises. In 1996, a 10,000-ton hydrometallurgical zinc smelting enterprise took ZZnAlD41 alloy as an example to develop die-casting zinc alloy and achieved success. At the same time, the alloy production capacity of 2500t/a was formed. The experiment explored a new process of low-temperature direct smelting of alloy, and the effect was good

Test method for

1.Test materials and equipment

Pure metal Zn 99.99 %, Al 99.85 %, Cu99.90 % and Mg 99.80% were used as raw materials, dried charcoal was used as covering agent, and industrial ammonium chloride was used as refining agent. Muffle furnace and graphite clay crucible were used to melt alloy and cast ingot. The industrial test was carried out in 750kg power frequency coreless induction furnace.

2 .Test technology

There are two kinds of die-casting zinc alloy melting processes: one is the one-step smelting process of melting copper first and adding aluminum, zinc and magnesium; The other is a two-step smelting process for pre-melting Al-Cu intermediate alloy and remelting zinc alloy. The former is rarely used in production because it must be operated at a high temperature of more than 1000℃. Although the latter is widely used, it still has the disadvantages of high temperature operation and complicated process.

For this reason, a new process of direct melting at low temperature of the alloy was put forward, that is, the required amount of copper was first added to the zinc melt, and then the amount of aluminum and magnesium and the remaining zinc were added successively. This method can overcome the shortcomings of the old technology, and the quality of the alloy ingot obtained by the test is completely qualified