Comparative Analysis of Anti-corrosion Surface Treatment of Aluminum Die Castings

Material

ZL102 (AlSi12, A04130, LM6)

Chemical composition

Silicon (Si): 10.0-13.0%; Aluminum (Al): balance; Iron (sand casting): 0.000~0.700%; Iron (metal casting): 0.000~1.000%; Copper (Cu): ≤0.30% ( Impurities); Manganese (Mn): ≤ 0.5% (Impurities); Magnesium (Mg): 0 ≤ 0.10% (Impurities); Zinc (Zn): ≤ 0.1% (Impurities); Titanium (Ti): ≤ 0.20% (Impurities) ). The total impurities are 2.0% for sand casting and 2.2% for metal casting.

Mechanical behavior

σb (MPa): ≥145, δ5 (%): ≥4, hardness HB: ≥50

Main characteristics of materials

1. It has good casting performance, low density and high corrosion resistance, and can withstand the corrosion effects of atmosphere, sea water, carbon dioxide, concentrated nitric acid, ammonia, sulfur and hydrogen peroxide; 2. As the wall thickness of the casting increases, the strength decreases to a low degree, it cannot be strengthened by heat treatment, the welding performance is good, the machinability and heat resistance are poor, and the finished product should be used under deterioration treatment.

Application areas

It is suitable for casting thin-walled parts with complex shapes, bearing low loads, and parts with high corrosion resistance and air tightness, and operating temperatures not exceeding 200°C, such as ship parts, instrument casings, machine covers, etc.

Salt spray test

The selected parts are the floor drain body made using the casting process. Air holes are easily produced during the casting process. This was successfully solved by adjusting the mold and presetting the exhaust pipeline. The floor drain cover is made using the die-casting process, and the upper surface is wire-drawn.

1. Surface anti-corrosion treatment: The ground floor body is treated with electrophoretic paint, and the control group is not subjected to surface treatment; the surface of the floor drain cover is chromium-plated and oxidized, and the control group is not subjected to surface treatment.

2. Salt spray anti-corrosion experiment

Equipment for salt spray testing: salt spray testing machine

The test is divided into four groups: electrophoretic paint experimental group, spot chromium plating experimental group, oxidation experimental group, and no treatment control group.

Salt spray test time: 48 hours.

Test comparison chart:

Experimental results: Electrophoretic paint has the best anti-corrosion effect, followed by chromium plating and oxidation. However, electrophoretic paint and chrome plating solutions may cause skin breakouts in some trachoma areas due to acid reflux.