Процес на анодизиране на титан и неговите сплави
Titanium alloy properties
(1) One of the most important properties oftitanium-alloy.html> titanium alloy is its low density and high specific strength. The density of titanium is 4.5 g/cm 3. Among commonly used metals, only aluminum has a density of 2.7 g/cm. It is lighter, but the strength of aluminum alloy is lower, while low carbon mace is 7.86 g/ca. . , stainless steel 80 g/cm, copper 89 g/cm, all higher than titanium. Due to the high specific strength of titanium alloy, it is considerable to use titanium alloy instead of steel and aluminum alloy to reduce the weight of the body structure. At the same time, it is the preferred material to reduce the structural volume. Under the same space size conditions, it can replace those affected by space. Limited aluminum alloy and steel components are of great significance for improving the service life and performance of aircraft structures.
(2) Another outstanding property of titanium and its alloys is their excellent corrosion resistance. The corrosion resistance of metals is related to the inherent properties of the metal. The thermodynamic stability of various metals can be roughly evaluated based on their standard equilibrium potential. Generally speaking, the higher the standard equilibrium potential (that is, the more positive), the more thermodynamically stable the metal is. The higher the stability, the smaller the tendency of metal ionization and the less susceptible it is to corrosion; and vice versa. Although titanium is a chemically active metal with a low standard equilibrium potential (negative) and a high thermodynamic corrosion tendency in media, titanium is actually very stable in many media because of its It has a strong tendency to passivate and has a great affinity with oxygen. When oxidized in air or in oxygen-containing media, an oxide film with good corrosion resistance is formed on the surface of titanium, which blocks further oxidation of titanium and its alloy matrix. Corrosion, which determines that titanium and its alloys have good chemical corrosion resistance. At the same time, due to the formation of a surface film with good protective properties and high resistivity on the surface of titanium and its alloys, the electrochemical corrosion resistance of titanium alloys is actually reflected in the electrochemical corrosion resistance of this surface film. Therefore, titanium Its titanium alloy has excellent electrochemical corrosion resistance.
(3) Titanium alloys have good compatibility with composite materials. Because composite materials have the advantages of high specific strength, high specific stiffness, good fatigue resistance, and good processability, as advanced composite material design and process technology become increasingly mature, like the titanium union, advanced composite materials, especially carbon fiber The application of epoxy composite materials (GECM) is increasing, and it has been used in important structures such as vertical tails, rudders, and wings of a variety of aircraft. Due to the unique electrochemical properties of carbon fiber, its electrode potential is relatively positive. After being electrically connected to the coupling metal material, the corrosion rate of the metal with a negative electrode potential will be accelerated in the corrosive medium.
Anodizing process of titanium and its alloys
The anodizing process is a traditional technology that electrolytically oxidizes the surface of metals and alloys to form an oxide film. The oxide film produced using this technology has uniform color, corrosion resistance, strong bonding force and good biocompatibility. It is widely used in modern biomedicine. It has been widely used in the fields of aerospace and aerospace.
The anodizing process of titanium uses titanium as the anode and stainless steel and other metals as the cathode. With the help of a certain electrolyte, the oxidation reaction occurs on the surface of the titanium alloy through an electrochemical reaction to form an oxide film. This oxide film has a very obvious reflection and refraction effect on light, and oxide films of different thicknesses will show different colors and are protective. Therefore, it is an ideal decorative layer and wear-resistant layer and is widely used in construction. , aviation, medicine and other fields.
Anodizing coloring method of titanium and its alloys
The anodizing and coloring process flow of titanium and its alloys is:
Degreasing (strong alkaline degreasing agent) → water washing → initial pickling (hydrofluoric acid aqueous solution) → water washing → secondary pickling (hydrofluoric acid + hydrogen peroxide aqueous solution) → water washing → anodizing (constant voltage in phosphoric acid aqueous solution) Electrolysis)→wash→sealed→dry.
1. Remove oil
Degreasing is to remove the oil remaining on the titanium surface during rolling. Because the oil-adhering part has poor water permeability, uneven coloring is prone to occur when pickling the titanium surface.
2. Initial pickling
The initial pickling is to form a pear-skin pattern on the surface of titanium and its alloys. Using hydrofluoric acid with a concentration of 5% by weight to pickle titanium can promote the formation of pear skin patterns.
3. Second pickling
The second pickling is to remove the powdery dirt formed on the surface by the first pickling. In addition, in order to avoid uneven pickling, it is necessary to use hydrofluoric acid and hydrogen peroxide aqueous solution to stabilize the titanium ions into a certain titanium-containing complex after the hydrofluoric acid dissolves the surface dirt once.
4. Anodizing
Using phosphoric acid with a concentration of 1% by weight in the electrolyte, the aluminum plate is used as the cathode, and the pre-treated titanium plate is used as the anode for constant voltage treatment. As the voltage increases, the oxide film on the titanium surface thickens, showing various color changes.
| Voltage（V） | 5 | 15 | 30 | 50 | 80 | 90 |
| Color and luster Film thickness (A) | Grayish yellow 100 | Brown 300 | Blue 500 | Yellow 700 | Purple 950 | Green 1300 |
5. Closed
In order to improve the corrosion resistance, anti-pollution and wear resistance of the anodized film, titanium and its alloys need to be sealed with hot water, steam, and solutions containing inorganic salts and organic matter after anodizing and coloring.
6. Dry
After sealing, wipe off the moisture on the workpiece with a clean cotton cloth and let it dry naturally.
In summary, it can be seen that the anodizing process of titanium and its alloys is relatively simple, and the colors formed on the surface are rich. In addition, the cost is relatively low, so it is easy to be popularized in industry and is a promising development prospect. Oxidation coloring technology.
