Acid pickling solution for die-casting aluminum alloy passivation technology

Abstract

The invention belongs to the technical field of metal surface treatment and relates to an acid pickling solution for the die-casting aluminum alloy passivation technology. The formula of the acid pickling solution comprises, by weight, 10-40% of fluorinated compounds, 0.5-5% of corrosion inhibitor, 1-5% of wetting agent, 10-20% of oxidizing agent, 0.2-2% of accelerator, and the balance deionized water. Through the acid pickling solution, yellow smoke can be prevented, the temperature cannot rise continuously in the reaction process, there is no need to add a cooling system, and the acid pickling solution is more suitable for continuous processing of an assembly line. A die-casting aluminum alloy product subjected to acid pickling can endure long-time exposure to the air without the surfaceblackening problem, and the overall effect of the passivated die-casting aluminum alloy product is improved.

Description

technical field [0001] The invention relates to the technical field of metal surface treatment, in particular to a pickling solution used in the passivation process of die-casting aluminum alloys. Background technique [0002] Aluminum is a low-density, versatile metal that oxidizes easily, so it needs a series of surface treatments before it can be used. [0003] Chinese invention application CN108728854A discloses a cleaning process for aluminum profiles. The steps include soaking, brushing, degreasing, water washing, pickling, surface conditioning, phosphating, passivation and water washing again. Among them, pickling uses a pickling solution of hydrofluoric acid + nitric acid. This kind of pickling solution has a short service life due to the active nitric acid component, and it will release a lot of heat during pickling, forming yellow smoke that seriously affects the environment. The quality is unstable and has great limitations in industrial production. Moreover, d...

AI Technical Summary

Problems solved by technology

This kind of pickling solution has a short service life due to the active nitric acid component, and it will release a lot of heat during pickling, forming yellow smoke that seriously affects the environment. The quality is unstable and has great limitations in industrial production

Moreover, die-casting aluminum is more active than profile aluminum, and is prone to blackening

[0004] There is also a pickling solution using ammonium bifluoride-hydrogen peroxide system on the market. Although it can avoid the problem of yellow smoke, it will continue to heat up during the continuous production process. Cooling equipment must be added to maintain the temperature, and it needs to quickly enter the washing process and enter the secondary process quickly. Washing with water, otherwise die-casting aluminum products are very easy to turn black in the air and in the process of washing with water, which will affect the quality of the final product and is not conducive to automated production

Images