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What are the characteristics of zinc aluminum alloy die castings?
- 2020-02-21-

Zinc alloy is an alloy composed of zinc added with other elements. Commonly added alloy elements are aluminum, copper, magnesium, cadmium, lead, titanium and other low-temperature zinc alloys. The zinc alloy has a low melting point, good fluidity, easy fusion welding, brazing and plastic processing, corrosion resistance in the atmosphere, and residual waste materials are easy to recover and remelt; but the creep strength is low and it is easy to cause dimensional changes caused by natural aging. Prepared by melting method, die-casting or pressure processing into materials.

According to the manufacturing process, it can be divided into cast zinc alloy and deformed zinc alloy. The main added elements of zinc alloy are aluminum, copper and magnesium. According to the processing technology, zinc alloys can be divided into two types: deformation and casting zinc alloys. Cast zinc alloy has good fluidity and corrosion resistance, and is suitable for die-casting instruments and automobile parts shells.

Features

1. Relatively large.

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2. The casting performance is good. It can die-cast precision parts with complex shapes and thin walls.

3. Surface treatment is possible: electroplating, spraying, painting, polishing, grinding, etc.

4. It does not absorb iron during melting and die casting, does not corrode the mold, and does not stick to the mold.

5. Has good mechanical properties and wear resistance at room temperature.

6. It has a low melting point and melts at 385 ° C, making it easy to die cast.

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kind

The traditional die-cast zinc alloys are 2, 3, 4, {{3}}, and 7 alloys, which are widely used {{1} } Zinc alloy. In the 1970s, high-aluminum zinc-based alloys ZA-8, ZA-1 2, ZA-2 7 were developed.

Zamak 3: Good fluidity and mechanical properties.

Used in castings that do not require high mechanical strength, such as toys, lamps, decorations, and some electrical devices.

Zamak 5: Good fluidity and good mechanical properties.

Used in castings that have certain requirements on mechanical strength, such as auto parts, electromechanical parts, mechanical parts, electrical components.

Zamak 2: It is used for mechanical parts with special requirements on mechanical properties, high hardness, good wear resistance and general dimensional accuracy.

ZA 8: Has good impact strength and dimensional stability, but poor fluidity.

Low temperature zinc alloy

It is used for workpieces with small size, high precision and mechanical strength, such as electrical devices.

Superloy: Strong fluidity, applied to die-casting thin-walled, large-sized, high-precision, complex-shaped workpieces, such as electrical components and their boxes.

Different zinc alloys have different physical and mechanical properties, which provides a choice for die casting design.

According to the manufacturing process, zinc alloys can be divided into cast zinc alloys and deformed zinc alloys. The output of cast alloy is much larger than that of deformed alloy. The following table lists the composition, properties and uses of several important zinc alloys.

According to different casting methods, casting zinc alloys are divided into pressure casting zinc alloys (solidified under the action of applied pressure) and gravity casting zinc alloys (solidified only under the action of gravity).

The pressure casting zinc alloy, which has been used in the automotive industry since 1940 years, has seen a sharp increase in production. About 25% of the total zinc consumption is used to produce this alloy. Advanced and applicable technologies are constantly being adopted and developed rapidly. The commonly used alloy system is Zn-Al-Cu-Mg system. Certain impurities significantly affect the performance of die-cast zinc alloys. Therefore, the content of impurities such as iron, lead, cadmium and tin is extremely restricted, and the upper limits are 0. 005%, 0. 004%, 0. 003%, 0. 02%, so high purity zinc with a purity greater than 99. 99% should be used as the raw material for die-casting zinc alloys.

Gravity casting zinc alloy can be cast in sand mold, gypsum mold or hard mold. This zinc alloy not only has the characteristics of general die-casting zinc alloy, but also has high strength, good casting performance, cooling speed has no obvious effect on mechanical properties, residual and scrap can be recycled, the gate is simple, insensitive to overheating and remelting, shrinkage The rate is small, the pores are few, can be electroplated, and can be finished by conventional methods.

In addition to the traditional varieties of deformed zinc alloys used in the deformed zinc alloy industry, Zn-Cu-0. 1 Ti and Zn-22Al alloys have appeared. After the former alloy is rolled, TiZn 1 5 intermetallic compound dispersed particles are arranged in a row along the rolling direction, which can hinder the movement of grain boundaries.