In recent years, the use of titanium in consumer electronics and other product sectors has surged in popularity, even becoming a standard material in the design of some high-end products. Examples include the mid-frames of high-end smartphones and the cases of smartwatches.
To achieve its sleek, premium look and enhance the surface properties of titanium products-such as hardness, toughness, and weather resistance-the range of surface treatment processes has become increasingly diverse. These include anodizing, high-temperature crystallization, brushing, liquid-phase coating, electroplating, laser etching, sandblasting, polishing, electrophoresis, CNC machining, and etching. This article explores these techniques through specific product design case studies.
Let's briefly summarize the design directions for titanium products and the types of processes selected.
- For a glossy and smooth finish: Choose polishing;
- For rich colors and hardness: Choose anodizing;
- For versatility or special colors: Choose PVD coating or liquid-phase coating;
- For a matte, textured surface: Choose brushed finish;
- For deburring or a matte finish: Choose sandblasting;
- For artistic patterns and textures: Choose chemical etching, CNC machining, laser engraving, or high-temperature crystallization;
I. Anodizing
Key Points: Coloring, improving surface properties, and creating patterns
Like aluminum alloys, anodizing is one of the most common surface treatment processes for titanium. The principle involves an electrolytic process in which titanium is immersed in a specific solution, forming a nanoscale titanium dioxide oxide film on the surface. The oxide film itself is colorless, but it causes light to interfere and refract on its surface, creating unique visual colors. The thickness of the anodized oxide film varies with the electrolytic voltage, allowing the titanium surface to produce colors such as brown, purple, blue, gold, green, and pink. The entire process requires no paints or dyes. It is applicable in fields such as medical devices, household goods (cups, bowls, cutlery, etc.), and consumer electronics.
II. High-Temperature Crystallization
Key Features: Texture, Patterns, Satin Finish, Fingerprint Resistance, Artistic Appeal
During heating, titanium undergoes an allotropic transformation. Its phase transition temperature is 882.5°C; at this temperature, titanium transforms from the hexagonal close-packed (h-cpc) α phase to the body-centered cubic (bcc) β phase. During this production process, if the temperature is further raised to 1000°C or higher, crystalline structures will form on the titanium surface. These structures gradually grow larger and more uniform as the temperature rises, resulting in the unique surface textures and patterns characteristic of titanium. This process is applicable to fields such as consumer electronics, jewelry, tableware, art, and daily necessities.
III. Brushing Process
Key Features: Texture, Satin Finish, Fingerprint Resistance
Brushing is a process that preserves the natural texture of titanium. The titanium midframe of the iPhone 15 Pro features a brushed finish, achieved through a series of processes including precision machining, polishing, brushing, and sandblasting, resulting in a refined and delicate texture.
IV. Electroplating/PVD/AF Coating
Key Points: Coloration and Enhancement of Surface Properties
Surface coating processes for titanium primarily include electroplating, PVD, and AF. In the consumer electronics sector, the latter two are most commonly used, primarily to enhance product surface properties and extend service life, while also providing color effects.
V. Liquid-Phase Film Formation (Micro-Arc Oxidation)
Key Points: Coloring, Enhancing Surface Properties
Like anodizing, liquid-phase film formation technology involves forming a coating layer on the surface of titanium metal. It primarily utilizes high voltage to generate an arc discharge. Through the combined effects of thermochemical, plasma chemical, and electrochemical processes, a strongly bonded oxide ceramic coating is formed in situ on the substrate. This significantly enhances surface properties, including hardness, corrosion resistance, and electrical insulation. Additionally, it can be used for decorative coloring; no additional dyes are required, as the material itself provides the color. The coating thickness typically ranges from 5 to 20 micrometers.
VI. Polishing
Key Points: Enhancing surface finish and achieving a high-gloss effect
As one of the most common surface treatment processes for titanium, polishing enhances the surface finish of the product, removes imperfections, and creates either a high-gloss or matte finish, thereby improving the overall texture.
VII. Sandblasting
Key Features: Fine, matte finish and texture
Sandblasting titanium creates a fine, matte finish on the surface. For example, the titanium frame of the Samsung Galaxy S25 Ultra features a significantly improved tactile feel after sandblasting.
VIII. Laser Engraving
Key Features: Localized, High Precision, Artistic
Laser engraving is primarily used on titanium alloys to create text, logos, and intricate patterns. It is characterized by high precision and efficiency.
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