[China Aluminum Industry Network] Anodic oxidation process conditions are closely related to the quality of the oxide film, because the process conditions are based on different process recipes, after a series of experiments, before the anodization, the specified process The conditions should all be known and should be done strictly in accordance with the process requirements. One of the more basic and sensitive factors is the control range of the solution temperature, voltage and current density, the anodizing time, the solution stirring method, the current density of the bath volume, the ratio of the bath volume to the anodized area, etc. . If there are deviations during the execution of these process conditions, the quality of the anodized film will be significantly affected. When the deviation is too large, the parts may be scrapped, resulting in economic losses. When the process conditions exceed the control range, the degree of influence on the quality of the anodized film, the different symptoms, and the corrective methods are discussed separately in the following questions. How to control the voltage when anodizing? The voltage adjustment depends on the temperature of the solution. When the solution temperature is lower, the upper limit voltage should be used. This is because the oxide film obtained when the solution temperature is low is dense and the resistance of the oxide film is large. To increase the oxide film, it is necessary to adopt a higher voltage, otherwise it is difficult to obtain normal oxidation. Film quality. When the temperature of the solution is high, the voltage is reduced. Otherwise, the resulting oxide film is loose and the film solution is too fast, making it difficult to obtain a desired thickness of the oxide film. For example, in a unit without a cooling device, the temperature of the solution in summer will be close to the limit temperature. If it is still necessary to continue working, the voltage may not exceed 12V. The temperature of the solution in winter is lower than the lower limit of the limit temperature, when the voltage rises to a high value, such as 18V. Anodizing is an exothermic reaction. When the workload is full, the temperature of the solution will gradually rise. Therefore, it must be tested at any time to provide the basis for adjusting the voltage. If the temperature continues to increase, it is difficult to ensure quality even if the voltage is below the specification. At this point, production should be stopped. Take appropriate measures to reduce the temperature, and then proceed with the process requirements. How to control the current density when anodizing? Under normal temperature conditions (about 20°C), in addition to the special process recipes, the current density of the anodized aluminum and its alloys is generally controlled between 1 and 1.5 A/dm2. Select according to the temperature of the solution, the concentration of the solution, the shape of the part, and other relevant process conditions. Under possible conditions, an appropriate increase in current density is favorable for accelerating the generation rate of the film, shortening the anodizing time, increasing the porosity of the film, and improving the coloring effect. However, when the current density continues to increase, the effect of Joule heating will increase during the anodization process, the thermal effect in the film pores will increase, and the local temperature rise will be significant. As a result, the dissolution rate of the oxide film will increase, and the deposition rate will decrease. The pieces will also cause uneven current distribution and affect the coloring effect. A loose oxide film that may be easily wiped off may also appear on the surface of the article, or the film may be brittle, cracked, or appear white marks. In severe cases, ablation products may also be caused. Choosing an appropriate current density can accelerate the growth rate of the film within a certain range, but when it exceeds a certain value, the film formation rate decreases. According to the above rules, in order to ensure product quality and increase production efficiency, the following methods can be taken. When the cooling conditions are good and the solution can meet the strong stirring, the upper limit of the current density can be used to improve the working efficiency. In the absence of cooling device and no strong stirring, although the temperature of the solution is moderate at the time, the current density must be properly controlled to prevent quality problems due to excessive heating during the anodizing process. In severe cases, it may also cause artifacts. Ablation. The more effective method at this time is to reduce the volume current density. The correct estimation of the surface area of ​​anodized parts is also an important condition for reasonable control of current density and should be considered. The surface of the anodized part in the deep part should be delivered with the same current density as other surfaces. The PHROXI Metal handle kitchen faucet have Stainless steel spring.For cleanup and prep, the Kitchen Faucet moves with you, thanks to its flexible coil feature and pull-down spray. Kitchen Faucet,Kitchen Taps,Kitchen Faucets,Kitchen Sink Faucets HESHAN CAIZUN SANITRAYWARE CO.,LTD , https://www.caizunbathroom.com
What is the relationship between oxide film quality and various processes?