What are the characteristics and types of zinc alloys?

characteristic
1. Relatively high specific gravity.
2. Good casting performance, capable of die-casting complex and thin-walled precision parts, with a smooth casting surface.
3. Surface treatment can be carried out: electroplating, spraying, painting, polishing, grinding, etc.
4. During melting and die casting, it does not absorb iron, does not corrode the mold, and does not stick to the mold.
5. It has excellent mechanical properties and wear resistance at room temperature.
6. Low melting point, melts at 385 ℃, easy to die cast.
type
Traditional die-casting zinc alloys include alloys 2, 3, 4, 5, and 7, with the most widely used being alloy 3. In the 1970s, high aluminum zinc based alloys ZA-8, ZA-12, and ZA-27 were developed.
Zamak 3: Good fluidity and mechanical properties.
Applied to castings with low mechanical strength requirements, such as toys, lamps, decorations, and some electrical components.
Zamak 5: Good fluidity and excellent mechanical properties.
Applied to castings with certain requirements for mechanical strength, such as automotive parts, electromechanical parts, mechanical components, and electrical components.
Zamak 2: Used for mechanical parts with special requirements for mechanical properties, high hardness, good wear resistance, and general dimensional accuracy.
ZA8: Has good impact strength and dimensional stability, but poor fluidity.
Applied to workpieces with small die-casting dimensions, high precision and mechanical strength requirements, such as electrical components.
Superloy: With optimal fluidity, it is suitable for die-casting thin-walled, large-sized, high-precision, and complex shaped workpieces, such as electrical components and their boxes.
Different zinc alloys have different physical and mechanical properties, providing a space for selection in die-casting design.
Zinc alloys can be divided into two categories based on manufacturing processes: cast zinc alloys and deformed zinc alloys. The production of cast alloys is much higher than that of deformed alloys.
Casting zinc alloys can be divided into pressure casting zinc alloys (solidified under external pressure) and gravity casting zinc alloys (solidified only under gravity) depending on the casting method.
Pressure cast zinc alloy: Since its application in the automotive industry in 1940, the production of this alloy has increased dramatically, and about 25% of the total zinc consumption is used to produce this alloy. Advanced and applicable technologies are constantly being adopted and developing rapidly. The most commonly used alloy system is Zn Al Cu Mg system. Some impurities significantly affect the performance of die cast zinc alloys. Therefore, the content limits for impurities such as iron, lead, cadmium, and tin are extremely strict, with upper limits of 0.005%, 0.004%, 0.003%, and 0.02%, respectively. Therefore, high-purity zinc with a purity greater than 99.99% should be selected as the raw material for die-casting zinc alloys.
Gravity casting zinc alloy: can be cast in sand molds, gypsum molds, or hard molds. This zinc alloy not only has the characteristics of general die cast zinc alloys, but also has high strength, good casting performance, and cooling speed has no significant effect on mechanical properties. Residual and waste materials can be recycled, the sprue is simple, insensitive to overheating and remelting, small shrinkage rate, few pores, can be electroplated, and can be refined by conventional methods.
In addition to traditional varieties, Zn-Cu-0.1Ti and Zn-22Al alloys have been developed for the industrial application of deformed zinc alloys. After rolling, the former alloy has TiZn15 intermetallic compound dispersed particles arranged in rows along the rolling direction, which can hinder the movement of grain boundaries.