The features of zinc alloy
1: Zinc alloy, than the major.
2: Good casting performance, can die-cast complex, thin-walled precision parts, casting surface smooth.
3. Surface treatment: electroplating, spraying and painting.
4: No iron absorption, no corrosion, no mold sticking when melting and die-casting.
5: Good mechanical properties and wear resistance at room temperature.
6: Low melting point, melting at 385℃, easy die-casting molding.
Problems to be paid attention to during use:
1: Poor corrosion resistance
When the impurity elements of lead, cadmium and tin in the alloy exceed the standard, the aging of the castings will lead to deformation, such as bulk expansion, significant decline in mechanical properties, especially in plasticity, long time and even fracture.
The solubility of lead, tin, and cadmium in the zinc alloy is very small, so the concentration at the grain boundary becomes the cathode, and the aluminum-rich solid solution becomes the anode, facilitating the intercrystalline electrochemical corrosion in the presence of water vapor (electrolyte). Die casting is aged by intergranular corrosion.
2: Time effect
The structure of zinc-alloy is mainly composed of zinc-rich solid solution containing Al and Cu and zinc-rich Al solid solution containing Zn,their solubility decreases with the decrease of temperature.
However, due to the rapid solidification rate of die casting, the solubility of the solid solution is greatly saturated at room temperature.
After a certain period of time, the phenomenon of supersaturation will be gradually removed, resulting in a slight change in the shape and size of the casting.
3: Temperature effect
Zinc alloy die castings should not be used in high temperature and low temperature (below 0℃) working environment.
Zinc alloys have better mechanical properties at room temperature.
However, the tensile strength at high temperature and the impact performance at low temperature decrease significantly.