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How to Maintain Alkali Etching Tank

Release time:

2022-06-24 15:27

1、Maintenance of ingredients

According to the production process of aluminum alloy anodic oxidation, after producing a certain amount of aluminum, the alkali etching bath solution should be analyzed. The aluminum ion of the alkaline etching solution is as high as 120~130g/L, and the NaOH is maintained between 40~60g/L. Due to the addition of additives composed of a variety of substances in the alkaline etching tank, the content of NaAlO2 in the solution reaches 350~400g/L, the alkaline etching solution is very strong, and the content of aluminum ions is very high, which all belong to the normal range. However, in the production process, we must detect the concentration of the components of the bath every day. Once it is not within the normal range, additives or sodium hydroxide should be added in time even if the production is normal. Otherwise, when Al(OH)3 crystal nuclei are formed, Al(OH)3 precipitation is easily generated, resulting in quality problems of the products and shortening the service life of the bath. When the aluminum ion in the bath exceeds 130g/L, only part of the bath can be discharged, a part of the water can be added, and the concentration can be adjusted to a suitable concentration with sodium hydroxide and additives.

Only by maintaining the concentration of the components of the bath solution within the normal range for a long time for production, can the life of the bath solution be maintained and high-quality aluminum products be produced.

2、Common problems and troubleshooting methods

over-corrosion fault

If the cause of the over-corrosion phenomenon is that the concentration of alkali is too large, it is necessary to dilute the bath solution: if the temperature is too high or the time is too long, it can be adjusted by cooling or shortening the operation time.

Too slow corrosion rate

This failure is just the opposite of the above-mentioned failure. The reasons are: the concentration of alkali is too dilute, the temperature is too low or the time is too short, so it can be solved by the opposite method to the above, that is, adding alkali, heating or prolonging the time.

After corrosion, the product has flow marks and reflective spots.

The reason for this phenomenon is that the bath liquid is contaminated by zinc impurities, which can be eliminated by replacing the bath liquid or adding zinc inhibition additives.

Precipitation occurs in the tank liquid and agglomeration occurs at the bottom of the tank.

This is because the concentration of aluminum ions is too high or the amount of additives is insufficient, the solution is to discharge a part of the bath liquid, add water and additives; If the concentration of aluminum ions is too high but because the amount of additives in the bath is insufficient, add additives.