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Analysis of Acid Pickling Process for Titanium and Titanium Alloy Processing Materials

In the production process of titanium and titanium alloy processed materials, removing oxide scale is a crucial step, and acid washing is the main means to achieve this goal. Before acid washing, titanium materials usually need to be pre treated, such as molten alkali washing, mechanical descaling, or sandblasting, to remove most of the surface dirt and thick oxide layer, creating favorable conditions for subsequent acid washing.
Acid washing is a very effective method for removing slight titanium oxide films formed below 600 ℃. During the pickling process, titanium reacts chemically with the acid solution to form metal ions, thereby achieving the removal of oxide scale. However, acid washing of titanium is not just a simple chemical reaction, it also involves electrochemical phenomena.
When pickling in mixed acid solutions containing hydrofluoric acid or fluoride, special attention should be paid to the reduction reaction of hydrogen ions. These hydrogen ions may be reduced to atomic hydrogen or molecular hydrogen. Among them, molecular hydrogen has a tendency to diffuse into the interior of metals. Once it enters the interior of metals, it may cause hydrogen embrittlement, seriously affecting the performance and service life of titanium materials.
Therefore, during the pickling of titanium materials, it is necessary to strictly control the composition and proportion of the acid solution to prevent hydrogen absorption. Specifically, it is necessary to always maintain a ratio of nitric acid to hydrofluoric acid greater than 5. The control of this ratio is crucial for preventing hydrogen embrittlement. However, it should also be noted that the nitric acid content should not be too high, as excessive nitric acid content can lead to a decrease in reaction rate, production efficiency, and the production of a large amount of smoke, which poses difficulties for operation.
In addition, it is necessary to pay attention to the control of process parameters such as temperature and time during the pickling process. Excessive temperature or prolonged time can lead to excessive corrosion of titanium materials, affecting surface quality. Therefore, in practical operation, it is necessary to adjust the pickling process parameters reasonably based on factors such as the material, thickness, and severity of the oxide scale of the titanium material to ensure the effectiveness of pickling.
In short, the pickling process of titanium and titanium alloy processed materials is a complex and delicate task. Only by strictly controlling the composition, proportion, and process parameters of the acid solution can the pickling effect be ensured while avoiding unnecessary damage to the titanium material. Interested friends can continue to follow our sharing to learn more about the knowledge and technology of titanium metal in production.

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