To quicken the speed of aluminum alkaline etching, can in the sodium hydroxide as the base of the alkaline etching solution with sodium nitrate and sodium nitrite, plus grapes additive such as sodium method, in addition to tank liquid concentration, temperature, the etching time of factors will affect the rate of industrial aluminum alkaline etching, and how to control these factors.
Bath concentration
Will become alkaline sodium hydroxide dissolved in water solution, such solution is commonly used in aluminium profile using chemical cleaning tank solution, which is alkaline etching solution, alkaline etching solution of sodium hydroxide is ion state of existence, as the concentration of sodium hydroxide to rise to 250 g/L, speed also increases as the erosion of industrial aluminum profiles, thus it can be seen, The higher the concentration of sodium hydroxide in the tank, the faster the corrosion rate, but now many enterprises in order to save costs, the content of sodium hydroxide is controlled within the range of 50-100g/L. In order to control the content of sodium hydroxide, gluconate can be added to the tank by adding longevity additives, so that the content of free sodium hydroxide is within the range of 70g/L.
Amount of soluble
The aluminum in the sodium hydroxide alkaline solution reacts with sodium hydroxide to generate aluminum hydroxide, aluminum is influenced by products, aluminum etching rate decreases, the experiments show that when the amount of dissolved aluminum of 26 g/L, the concentration of sodium hydroxide to 50 g/L, the higher the temperature, the slow erosion of aluminum, thus, bath concentration under the condition of unchanged, the higher the amount of dissolved aluminum, The slower the rate of etching, that is, the amount of dissolved aluminum is inversely proportional to the rate of etching. To obtain the appropriate amount of dissolved aluminum through calculation, pay attention to the change of the tank, according to the situation will be controlled within the specified range of dissolved aluminum.
Bath temperature
Through the test of 6063 aluminum profile, we draw the conclusion that with the rise of the temperature of the tank, the alkali corrosion rate of aluminum also rises rapidly. Every 10℃ increase in temperature, the speed of aluminum corrosion reaction will be increased by 1 times, so the higher the temperature, the faster the alkali corrosion rate of aluminum profile, that is to say, the temperature of the tank is proportional to the corrosion rate. This is because the corrosion of aluminum in alkali etching solution is an exothermic reaction, can release 20kw/m² heat, usually need to install a cooling device with sufficient cooling capacity, so that the temperature of the tank is kept within the range of 50-60℃², this device can be used as a heating device in winter.
Etching time
In the alkali erosion reaction, the longer the erosion of industrial aluminum profile, aluminum dissolved the greater weight loss, and the etching time and etching speed and there is no direct relationship, shorten the etching time can only reduce the weight of the aluminum dissolved loss, reduce the reagent consumption, alkaline etching and etching speed out of proportion, if you want to get the smooth surface of the aluminium profile, It can be processed by mechanical brushing or sandblasting, or by improving the quality of the mold and extrusion process to achieve the effect of brightness and flatness.
