When beryllium bronze workpiece is heat-treated, it forms an oxidation mold on its surface. This outer oxide is a mixture of various copper oxides of beryllium oxide (BeO). The composition and thickness of this oxide film depend on the temperature of the heat treatment and the atmosphere in the furnace. The main thing is to remember that beryllium has a strong affinity for oxygen, but because beryllium oxide cannot be recovered by hydrogen, there is no heat treatment atmosphere to ensure that there is no beryllium oxide on the surface of beryllium bronze parts.
From the concept of cleaning beryllium bronze, these scenes are very important, because BeO is not simply cleaned by acid. Not only does it form a thinner oxide at low temperatures, but the composition of the oxide at the moment also makes it simple to clean in the pickling tank. The holding time at a certain temperature and the type of “lazy atmosphere” also affect the beryllium bronze Constituent factors of oxide film thickness.
- The cleaning of beryllium bronze, how many oxides there are, what type of oxides, and the ease of cleaning depend on the conditions and processes of heat treatment. Heat treatment has a clean appearance without oil stains and other stains. The beryllium bronze simplifies the cleaning work after heat treatment. In any case, the operation should be standardized.
- The advantage of the acid/hydrogen peroxide series is that it is easy to handle and the waste liquid is easy to handle. The reaction of pickling beryllium bronze is mild and no harmful vapors occur. There may be a guiding system for sulfuric acid vapor to discharge exhaust gas. Sulfuric acid/hydrogen peroxide lotion is a well-known “brightener”, which makes the appearance of the product bright and dull, and needs to be washed with cold water.
- Beryllium bronze in most of the acid immersion or cleaning process, if the metal has not been passivated in the area, then its appearance should become smoother, or soon become smooth. Generally speaking, before pickling, the surface should remove grease, carbonaceous substances or other sludge as much as possible. This may use a good alkaline cleaner before pickling, so that the cleanliness of beryllium bronze can reach a good effect .
The cleaned beryllium bronze surface cannot be electroplated or tinned immediately. It is necessary to select maintenance to avoid discoloration of the surface during storage. Usually, BTA can use a copper alloy rust inhibitor. The BTA film can be easily removed in the cleaning solution and use it to maintain the appearance of beryllium bronze for a long period of time at temperatures up to 300F.
The reaction rate is controlled by hydrogen peroxide (H2O2) content and temperature. The content of sulfuric acid changes from 10 (volume)% to 20 (volume)%, and has little effect on the reaction rate. The beryllium bronze dissolved in the acid solution can cool the acid wash to 60F, so that CuSO4 and 5H2O crystallize out of the solution. This pickling solution can be used repeatedly. If there is no spare part to control the copper ion concentration of the pickling solution, the limit solubility of copper sulfate is changed. The hydrogen peroxide in the solution needs to be stabilized to avoid the rapid damage to beryllium bronze due to its oxidation ability.