Problems needing attention in the use of zinc alloy diecasting
1., poor corrosion resistance. When the impurity elements lead, cadmium and tin in the alloy exceed the standard, the casting will be aged and deformed, which will lead to volume expansion, mechanical properties, especially plasticity, decrease significantly, and even rupture for a long time. Zinc alloy die casting]
The solubility of Pb, Sn and Cd in zinc alloy is very small, so they concentrate on the grain boundary and become cathode. The solid solution rich in Al becomes anode. In the presence of water vapor (electrolyte), intergranular electrochemical corrosion is promoted. Die castings are aged due to intergranular corrosion.
Comparison of various die casting zinc alloys
1. gas furnace production process
High purity zinc liquid is used as raw material for alloy production, and the phenomenon of increasing iron due to melting of mixer is avoided by gas furnace. In order to control the alloy ingots within the range of + 0.3Kg, graphite cone was used to control flow rate. The process is simple and the production cost is low. However, the defect of the gas furnace is low direct yield, and mechanical stirring makes the composition uniformity of the alloy liquid poor.
2. electric furnace production process
Zinc is melted and slag removed in a high-power power power frequency cored furnace, and then zinc liquid is discharged from the hole of the furnace, and then flowed into a coreless furnace to melt and form alloy liquid. The alloy liquid is poured out by a tilting device, flowed into a holding furnace through a chute, then scooped out by a mechanical spoon, and then injected into a zinc mold.
The biggest defect of zinc alloy die casting is that there is more slag in the process from coreless furnace to resistance furnace. Moreover, the creeping vibration of the straight ingot casting machine is unfavorable to the quality of the surface of the gold ingot. At the same time, the energy consumption is large.
