Removal Technology of Oxide Film on Titanium Alloy Rods

In industrial production, the degree of oxidation of titanium alloy rods can vary significantly. If the oxidation in the previous process is severe, such as severe oxidation under high-temperature conditions, resulting in the formation of oxide scale, then sandblasting treatment must be carried out. After sandblasting, the workpiece still needs to undergo subsequent processes (alkali washing and acid washing). If the oxide film is thin, no sandblasting treatment is necessary and acid washing can be directly performed.

Titanium dioxide is a bidentate compound, with its alkalinity slightly greater than its acidity. Titanium dioxide has excellent thermal stability, only decomposing at very high temperatures. Its chemical stability is also good, and it has good stability in many inorganic and organic media at lower temperatures. It does not dissolve in water or many other solvents, nor does it dissolve in various dilute acids except hydrofluoric acid. Titanium dioxide also hardly dissolves in concentrated sulfuric acid. However, titanium dioxide can dissolve in hot concentrated sulfuric acid, nitric acid, and sodium hydroxide solutions, which enables the alkaline washing and acid washing of titanium screws and titanium alloy rods.

The alkaline washing of titanium alloy rods, including those with other rare metals, is carried out in molten alkaline solution, with the aim of removing the oxide scale on the surface of the workpiece from the surface of the workpiece. The action of the alkaline solution can remove the oxide scale. However, in order to remove the oxide scale from the surface of the workpiece while avoiding the side effects caused thereby, an oxidant (NaN03 or KNO3) must be added in the NaOH molten liquid.

The main parameters affecting the alkaline washing process are the composition of the alkaline solution, the temperature and time of the alkaline washing.