An In-depth Look At The Art And Science Of Passivation Of Titanium Alloys

In the field of metal surface treatment, passivation is a crucial technology, which is like putting a layer of invisible armor on the metal to resist external erosion and extend its service life. This process is especially critical for titanium alloys, which shine in aerospace, medical, chemical and other fields because of their lightweight, high strength and corrosion-resistant properties. The passivation of titanium alloys is an important guarantee of their excellent performance.
First, the mystery of electrochemical passivation
Electrochemical passivation, is through the role of the current, in the titanium alloy surface induces the generation of a layer of dense and stable oxide film. Among them, the anodic oxidation method is particularly striking. When titanium alloys are placed in an electrolytic solution as an anode and the appropriate voltage is applied, an almost transparent oxide film is gradually formed on the surface. This film can not only effectively isolate the corrosive medium, but also through the interference effect of light, showing a brilliant and colorful color, from the elegant silver gray to the deep blue violet, each color is the perfect fusion of science and aesthetics.

The details of the anodizing method:
Selection of electrolyte: Usually a mixture containing phosphoric acid, sulfuric acid and other ingredients are used, which can promote the uniform growth of the oxidized film.
Control of voltage and time: the level of voltage directly affects the thickness and color of the oxide film, while the time determines the full extent of the oxidation reaction. Too high a voltage or too long a time may lead to too thick a film, or even cause the film to crack.
Post-treatment: After oxidization is completed, cleaning and hole sealing are required to ensure the integrity and stability of the oxide film.
Second, the art of heat treatment passivation
Heat treatment passivation, on the other hand, is the use of high temperature oxidation reaction, the formation of a layer of solid oxide layer on the surface of titanium alloy. This process is similar to nature's "nirvana in the fire", through the baptism of high temperature, the surface of titanium alloy has become more indestructible. The rapid cooling process ensures that the oxidized layer cures quickly, forming a dense structure that improves its corrosion resistance.
Key element:
Temperature control: Temperature is the core parameter of heat treatment passivation. Too high a temperature will result in an overly thick and easily flaking oxide layer, while too low a temperature will not form an effective oxide layer.
Holding time: The length of the holding time determines the thickness and uniformity of the oxide layer.
Rapid cooling technology: the speed of rapid cooling directly affects the structure and performance of the oxide layer.
Third, the fine process of chemical treatment passivation
Chemical treatment passivation, including pickling and chemical passivation two steps. Pickling can remove oil, oxides and other impurities on the surface of titanium alloy to create a clean substrate for subsequent chemical passivation. Chemical passivation, on the other hand, reacts with the surface of the titanium alloy through specific chemicals to create a dense oxide film.
Detailed operation of pickling passivation:
Pre-treatment: Mechanical cleaning and degreasing are essential pre-steps that ensure the cleanliness of the titanium alloy surface.
Pickling solution selection and proportioning: Nitric acid solution is preferred because of its strong oxidizing properties and good compatibility with titanium alloys. However, attention should be paid to the accuracy of the ratio to prevent the production of harmful "yellow smoke".
Time control: Acid cleaning time should be precisely grasped, too long will introduce too much hydrogen, affecting the performance of titanium alloy; too short will not achieve the desired cleaning effect.
Post-treatment: Water washing and drying are the key steps to ensure the effectiveness of pickling. Water washing needs to remove the residual acid completely, while drying needs to avoid leaving water stains on the surface.
Titanium passivation is a technology that combines science and art. Through electrochemical, thermal and chemical treatments, we are able to build a strong and beautiful oxide layer on the surface of titanium alloys, which significantly improves their corrosion resistance and surface quality. In the future development, with the progress of science and technology and process innovation, titanium alloy passivation treatment technology will usher in a broader application prospects.