There are many factors that affect the alkaline etching speed of aluminum profiles. In order to accelerate the alkaline etching speed of aluminum radiators, sodium nitrate or nitrite is usually added to the alkaline etching solution, followed by additives such as sodium gluconate. This can greatly improve the etching speed. In addition, the erosion rate is also closely related to the concentration and temperature factors of the tank liquid. Below, we will discuss these factors in detail.

Dissolving sodium hydroxide in water becomes an alkaline solution, which is usually used for the chemical cleaning tank solution of aluminum profiles, that is, an alkaline etching solution. The sodium hydroxide in the alkaline etching solution exists in the form of free ions. Experiments have shown that when the concentration of sodium hydroxide increases to 250g/L, the etching speed of aluminum profiles significantly increases, and as the concentration of sodium hydroxide in the tank solution increases, the etching speed becomes faster. In order to save costs, aluminum radiator manufacturers control the content of sodium hydroxide within the range of 50-100g/L. In order to find a balance between cost and speed, we can add gluconate to the tank solution by adding longevity additives, so that the content of free sodium hydroxide is within the range of 70g/L.

Place the aluminum profile in a sodium hydroxide alkaline solution, and the aluminum reacts with sodium hydroxide to form aluminum hydroxide. Due to the influence of the product, the corrosion rate of aluminum will decrease. Experiments have shown that when the amount of aluminum dissolved is 26g/L and the concentration of sodium hydroxide is 50g/L, the higher the temperature, the slower the corrosion rate of aluminum. From this, it can be seen that while the concentration of the bath solution remains constant, the higher the amount of aluminum dissolved, the slower the etching rate, i.e. the amount of aluminum dissolved is inversely proportional to the etching rate. To obtain the appropriate amount of aluminum dissolution through calculation, pay attention to observing the changes in the tank liquid, and control the amount of aluminum dissolution within the specified range according to the situation.

Through experiments on 6063 aluminum profiles, we have concluded that as the temperature of the bath increases, the alkaline etching rate of aluminum also rapidly increases. For every 10 ℃ increase in temperature, the rate of aluminum etching reaction doubles. Therefore, the higher the temperature, the faster the alkaline etching rate of aluminum profiles. In other words, the bath temperature is directly proportional to the etching rate. This is because the etching of aluminum profiles in alkaline etching solution is an exothermic reaction that can release 20kw/m ² The heat is too high, but if the temperature is too high, the evaporation of alkaline solution in the production process of aluminum radiators is faster, and high temperatures can easily cause discomfort to the human body. Therefore, it is usually necessary to install a cooling device with sufficient cooling capacity in the alkaline etching workshop to maintain the temperature of the tank liquid at 50-60 ℃ ² Within the scope, this device can also be used as a heating device in winter.

In the alkaline etching reaction, the longer the etching time of aluminum profiles, the greater the weight loss of aluminum dissolution due to the advantages of aluminum radiators. However, the etching time is not directly related to the etching speed. Shortening the etching time can reduce the weight loss of aluminum dissolution and reduce the consumption of alkaline etching agents, which is not proportional to the etching speed. If you want to obtain a smooth surface of aluminum profiles, you can only use mechanical brushing or sandblasting methods to process, or improve the quality of the mold and extrusion process to achieve a bright and flat effect.