The increasing need for titanium construction materials has led to increased expectations for the capabilities of titanium alloys. Titanium alloys are extensively utilized in aerospace, automotive manufacturing, architectural embellishment, and other domains owing to their lightweight nature, superior strength, and exceptional resistance to corrosion. The significance of surface treatment technology for titanium alloys becomes paramount in order to fulfill the performance standards required by diverse industries.
Overview of titanium alloy surface treatment methods
- Sand blasting: Use white corundum to rough blast the surface of titanium castings to remove sticky sand, sintered layer and part of the oxide layer. This process is usually controlled at a pressure below 0.45Mpa and a time range of 15 to 30 seconds.
- Chemical pickling involves the use of pickling solutions such as HF-HCl and HF-HNO삼 to effectively eliminate the reaction layer on the surface of titanium alloys and minimize contamination from other elements. Bright treatment can be achieved by controlling the HNO삼 concentration in HF-HNO삼 pickling solutions, which helps reduce hydrogen absorption.
- PVD coating: PVD is physical vapor deposition, a type of vacuum coating, and the process is very mature. It is possible to do PVD on the surface of titanium alloy, mainly to add functional coatings to play a protective role. But it is worth noting that at present, PVD can only be barely passed for functional purposes, and its durability needs to be improved, unless the performance of the PVD primer material is very good. Taking the iPhone 15 Pro as an example, among the 4 color schemes: black titanium, white titanium, blue titanium, and natural titanium, except for the original titanium silver color, the other three color schemes are combined with PVD coating technology on the basis of anode to increase the surface performance of the product, but fading and other adverse conditions still occurred later, which also reflects the shortcomings of PVD in durability.
- AC micro-arc oxidation: The base metal is directly converted into oxide ceramics through instantaneous high temperature and high pressure sintering in the micro-arc discharge zone, forming a thicker oxide film, which improves the wear resistance and corrosion resistance of titanium alloy.
- Ion implantation: Nitrogen ion implantation is a technique that enhances the tribological properties and hardness of titanium alloys, while still preserving the precise shape of the workpiece.
- Plasma nitriding and shot peening: A nitriding layer composed of TiN, Ti2N and other phases is formed on the surface of the titanium alloy, and shot peening is used for deformation strengthening post-treatment to improve wear resistance and strength.
- Laser cladding: Obtain excellent coating on the surface of titanium alloy, improve its high temperature wear resistance and corrosion resistance, and is often used for repairing gas turbine engine parts.
- Anodizing: Under certain conditions, such as after large ice flowers crystallize, anodizing is carried out to beautify the appearance and improve corrosion resistance. Most titanium coloring processes are achieved through anodizing, which can produce richer colors and patterns, with great differentiation, including ice crystals, threads and other options.
- Surface brushing: Drawing silk-like patterns on the surface of titanium alloy to increase the texture, which is commonly used in consumer electronics and other fields.
- Mirror polishing: Makes the surface of titanium alloy as smooth as a mirror with high reflectivity, suitable for occasions requiring aesthetics and high reflective performance. Featured product: Polished Titanium Ball
Moreover, pretreatment techniques, such as the utilization of molten salt, can be employed to enhance the effectiveness of the aforementioned methods. In real-world scenarios, a combination or selection of multiple treatment methods can be chosen to achieve optimal outcomes based on the specific applications and requirements of titanium alloys. Surface treatment technology plays a crucial role in meeting the performance standards of various industries when it comes to titanium alloys.
Special requirements for titanium alloy surface treatment
In addition to conventional mechanical properties, the surface treatment of titanium alloys also needs to consider some special requirements.
- Anti-discoloration treatment: Titanium is easily oxidized and discolored when in contact with oxygen. Glass and other coverings can be used to prevent or delay discoloration. Oxidation coloring and corrosion treatment can obtain unique artistic effects, such as colorful sculptures.
- Anti-glare treatment: The surface gloss is required to be low and the color is soft. Matt finishing, pickling, shot peening and other methods can be used to make the surface of the titanium plate slightly concave and convex to reduce the gloss.
In summary, different surface treatment technologies are available for titanium alloys, and suitable methods can be chosen based on specific requirements. As science and technology progress and demand increases, the development of titanium alloy surface treatment technology will further enhance its support for the application of titanium alloys.