In the middle and after the heat treatment, most of the […]
In the middle and after the heat treatment, most of the surface treatment is required to remove the oxide scale and various pollutants on the metal surface, reduce the activity of the bare metal surface, and coat the protective layer and various functional coatings on the surface of titanium and its alloys. Surface treatment should also be carried out before and during the coating process. The coating of this kind of coating is to improve the performance of the metal surface, for example, to prevent corrosion, oxidation and abrasion.
The pickling conditions of titanium and its alloys are determined by the types (characteristics) of the oxide layer and the existing reaction layer, and the type of this layer is affected by the high-temperature heating process and the increase of the processing temperature (such as forging, casting, welding, etc.). At a lower processing temperature or about 600X: only a thin oxide layer is formed under the following high temperature heating temperature conditions, and an oxygen-rich diffusion zone is formed near a certain oxide layer under high temperature conditions, which must also be eluted by acid In addition to this oxygen-rich diffusion layer. Various methods of removing scale can be used: the mechanical method of removing thick oxide layer and hard surface layer, the method of removing oxide scale in molten salt bath, and the method of removing oxide scale by acid elution in acid solution.
In many cases, a combination of several methods can be used, for example, a combination of mechanically removing oxide scale followed by pickling, or a combination of salt bath followed by pickling. In the case of the oxide layer and diffusion layer formed at a higher temperature, a special method must be used. However, when the oxide layer is heated to 600X at a high temperature, most of the oxide layer formed can be dissolved away by general pickling.