In order to speed up the alkali erosion of aluminum profiles, sodium nitrate or sodium nitrite can be added to the alkali etching solution based on sodium hydroxide, and then additives such as sodium glutamate.
Bath concentration
The sodium hydroxide is dissolved in water to become an alkaline solution, this solution is usually used for the chemical cleaning tank solution of aluminum profiles, that is, the alkali etching solution, the sodium hydroxide in the alkali etching solution is in the state of free ions, as the concentration of sodium hydroxide rises to 250g/L, the etching rate of industrial aluminum profiles also increases, it can be seen that the higher the concentration of sodium hydroxide in the bath, the faster the etching speed, but now many enterprises in order to save costs, the content of sodium hydroxide is controlled at 50-100g/ L. In order to control the content of sodium hydroxide, gluconate can be added to the bath solution by adding longevity additives, so that the content of free sodium hydroxide is within the range of 70g/L.
The amount of aluminium dissolved
Put the aluminum profile in the sodium hydroxide alkali solution, aluminum and sodium hydroxide chemical reaction to produce aluminum hydroxide, affected by the product, the corrosion rate of aluminum will be reduced, the experiment proves that when the amount of dissolved aluminum is 26g/L, the concentration of sodium hydroxide is 50g/L, the higher the temperature, the slower the corrosion rate of aluminum, it can be seen that the concentration of the tank remains unchanged, the higher the amount of dissolved aluminum, the slower the etching speed, that is, the amount of dissolved aluminum is inversely proportional to the etching rate. It is necessary to obtain the appropriate amount of dissolved aluminum by calculation, pay attention to the change of the bath liquid, and control the amount of dissolved aluminum within the specified range according to the situation.
Bath temperature
Through the test of 6063 aluminum profile, we conclude that with the increase of the temperature of the bath, the alkali corrosion rate of aluminum also rises rapidly, and the speed of aluminum erosion reaction will increase by 1 times for every 10 °C increase in temperature, so the higher the temperature, the faster the alkali erosion rate of the aluminum profile, that is to say, the temperature of the tank is proportional to the erosion rate. This is due to the fact that the etching of aluminum profiles in alkali etching solution is an exothermic reaction, which can release 20kw/m² of heat, and it is usually necessary to install a set of cooling devices with sufficient cooling capacity to keep the temperature of the bath liquid within the range of 50-60 °C², and this device can be used as a heating device in winter.
Erodation time
In the alkali etching reaction, the longer the etching time of the industrial aluminum profile, the greater the weight loss of aluminum dissolution, and the etching time is not directly related to the etching speed, shortening the etching time can only reduce the weight loss of aluminum dissolution, reduce the consumption of alkali etching agents, and the etching speed is not proportional, if you want to obtain a smooth aluminum profile surface, you can first take the method of mechanical brushing or sandblasting to process, or by improving the quality of the mold and the extrusion process quality to achieve the bright and smooth effect.
