Surface Treatment Technology For Titanium And Titanium Alloys To Prevent Adhesion
Surface Treatment Technology For Titanium And Titanium Alloys To Prevent Adhesion
Titanium alloy has been widely used in aerospace, military industry, civil industry and other fields because of its excellent specific strength, corrosion resistance, good high temperature properties and bio-compatibility. However, the surface hardness of titanium alloy is relatively low and the wear resistance is insufficient, which limits its application in certain environments. In order to improve these properties, researchers have developed a variety of surface treatment techniques to enhance the surface properties of titanium alloys.
1. Surface Oxidation Treatment
By forming a layer of oxide film, the lubricity of the surface of the titanium alloy is enhanced and the adhesion phenomenon in the drawing process is reduced.
2. Coating Treatment
1) Graphite emulsion coating
Applying graphite emulsion before thermal drawing not only provides lubrication, but also protects the surface of the blank from oxidation.The requirements for graphite emulsion include a graphite content of 20%-25%, a particle size of 1-3um, and can be evenly attached to the surface of the blank.
2) Salt lime coating
Use a specific formula of salt-lime lubricating layer, such as 12% Na2SO4, 12% CaO, 0.3% Na3PO4, 0.2% NaCl and margin water, supplemented by a mixture of 75% soap powder and 25% sulfur powder as a solid powdered lubricant.
3) Fluoro-phosphate treatment
After the surface of the metal blank is cleaned by physical methods, the solution is dipped to form a modified covering film on the surface, and then a solid lubricant is applied to obtain a lubricating effect with a low coefficient of friction and high wear resistance.
3. Gold-Plated Metal Film
A layer of metal film, such as copper, chromium, nickel or tin, is coated on the surface of the titanium alloy to reduce direct metal contact during drawing and thereby reduce adhesion.
4. Borization Treatment
The titanium alloy wire is placed in a mixed solution containing KFB4, BaCl2, and NH4NO3, heated to boiling and soaked, cleaned and dried after removal, so that a layer of fluoroborate is formed on the surface of the wire.When the cold pier is made, a layer of aluminum disulfide needs to be applied to the surface of the wire as a lubricant.
5. Chemical Conversion Treatment
Through chemical conversion treatment, a dense chemical conversion film is formed on the surface of the titanium alloy. This film can be used as a lubricating coating to adsorb lubricants, so that the surface of the wire is smooth after multiple draws, without adhesion and slippage
6. Lubricant Selection
Choose suitable lubricants, such as industrial soap powder, graphite emulsion, and mixtures of soap powder and other materials, which should have good wettability and good thermal stability with the coating.
7. Laser Surface Treatment
Laser treatment technologies include laser cladding, laser surface alloying and laser surface quenching, which can improve wear resistance, corrosion resistance and hardness by changing the micro-structure of the surface layer.The advantage of laser treatment is that it can achieve a significant improvement in surface performance without changing the properties of the titanium alloy matrix.
8. Micro-Arc Oxidation
This is a technique for growing a ceramic film in situ on the surface of a titanium alloy, which can form a layer of ceramic film with excellent corrosion resistance and wear resistance on the surface of the titanium alloy.Micro-arc oxidation technology has the characteristics of green environmental protection and is in line with the sustainable development strategy.
9. Ion Implantation
By injecting nitrogen, oxygen, carbon and other elements into the surface of the titanium alloy, the hardness and wear resistance of the surface can be improved.The thickness of the ion implantation layer is usually at the nanoscale, which can significantly improve the surface properties of titanium alloys.
10. Thermal Diffusion Method
By diffusing alloying elements to the surface of the titanium alloy at high temperature, an alloying layer is formed, thereby improving the hardness and wear resistance of the surface.