Effect of Aluminum Ion Concentration on Polishing Quality in Acidic Electrochemical Polishing Solution
[China Aluminum Network] In the electrochemical polishing solution, the control of aluminum ion concentration is an important aspect of polishing quality, because the concentration of aluminum ions and the viscosity of the polishing liquid are a constant value relationship. Before the aluminum ions in the solution have accumulated, the viscosity of the solution is low, which is unfavorable to the quality of the polishing. This is mainly reflected in the fact that some parts of the surface of the article have a grinding point and the brightness of the surface of the workpiece is also poor. In order to overcome this drawback, a suitable amount of old solution (the excess of aluminum in the old solution) can be added to the newly prepared polishing solution to compensate for the above-mentioned phenomenon that the viscosity is too low.
With the continuous electrochemical polishing, the concentration of aluminum ions in the solution will continuously increase, and the viscosity will increase accordingly. At this time, the current density should be increased accordingly, and the solution needs to be strengthened to stir. Only in this way can the quality requirements of high light brightness be met.
When electrochemical polishing is performed in a high-viscosity solution, since the current to be delivered is relatively high, a large amount of gas will be generated on the outer surface of the part, and it is difficult to escape under the cover of the mucous membrane, so that spot corrosion will also occur. .
To solve this problem, a temporary measure is to increase the temperature of the solution. A small amount of water may also be added to reduce the viscosity. However, increasing the temperature of the solution makes it inconvenient to operate. Adding water will reduce the acidity and make it difficult to obtain the desired brightness.
In order to maintain the stability of the solution, it is necessary to control the viscosity of the bath solution within a stable value, so that the concentration of aluminum ions is maintained at about 30g/L. When this value is exceeded, part of the solution should be promptly updated.