Anti-Discoloration Technology For Titanium Plate Processing

Titanium plates are easy to surface discoloration during processing, storage, and use, which not only damages the appearance integrity but also may weaken the surface protective performance, affecting the product's service life and application safety.

 

 

 

(1) Oxidation Reaction Caused by Processing Temperature

Titanium is highly susceptible to oxidation during high-temperature processing. If the temperature is out of control , titanium oxide of varying thicknesses will form on the surface, leading to discoloration. This loose oxide film not only affects the appearance but also reduces corrosion resistance.

 

(2) Environmental Media and Electrochemical Corrosion

Titanium plates are prone to electrochemical corrosion in environments such as humidity, marine atmosphere, and chemical media, resulting in changes in surface composition and microstructure, and surface darkening and loss of luster.

Among them, chloride ions in the marine environment will damage the passive film on the surface of titanium plates, causing local corrosion;

water vapor in the humid environment will accelerate oxidation and exacerbate the loss of luster.

 

(3) Surface Contamination and Process Residues

Surface contamination during processing, storage, and transportation is an important cause of local discoloration of titanium plates. Contaminants such as fingerprints, oil stains, abrasive debris, and dust not only affect the appearance but also may react with the surface of titanium plates-for example, oil stains carbonize at high temperatures to form black spots, and sweat can cause local corrosion to produce color spots.

 

 

(1) Precision Polishing Pretreatment Technology

Polishing by abrasive friction, featuring low cost, high efficiency, and little impact on dimensional accuracy. The abrasive consists of 4-10 parts of silicon carbide and 90-96 parts of polishing sand. Hainan sand has a unit price only half that of corundum sand, offering high cost performance. This process has no chemical reactions and no secondary pollution, making it suitable for batch processing of titanium plates for construction.

 

Irradiating the titanium plate surface with an electron beam to instantly melt and solidify the 10μm surface layer, significantly improving surface flatness with roughness reducible to below 0.1μm. It does not require contact with abrasives, avoiding secondary pollution, and is suitable for high-precision titanium plate processing in aerospace, medical devices, and other fields.

 

(2) Anodic Oxide Film Strengthening Technology

Anodic oxidation is the core technology for titanium plate protection. A dense, colorless titanium oxide film (5-30μm) is formed on the surface through electrolysis, which has both oxidation and corrosion resistance and can replace the primer.

 

In the process, sulfuric acid, chromic acid, or oxalic acid systems are often selected, combined with a smooth DC power supply to ensure uniform film thickness. The key is to strictly control parameters to prevent surface yellowing caused by excessive oxidation, which affects subsequent coating adhesion.

 

(3) Protective Coating Preparation Technology

Spraying a protective coating on the anodic oxide film can further improve the anti-discoloration ability of titanium plates, among which fluorocarbon spraying is the most widely used. Fluorocarbon coatings have rich colors, UV resistance, anti-chalking properties, and long service life, making them suitable for scenarios such as building roofs and outdoor chemical equipment.

 

Construction requires strict control of details: temperature below 200°C, using a gravity feed spray gun, following the principle of "move the gun first before opening the valve, and close the valve first before stopping the gun" to avoid uneven coating thickness.

 

This process can form a "double protection of oxide film + organic coating" to resist sunlight, rain, and corrosive media. In addition, high-temperature resistant ceramic coatings can be selected for high-temperature working conditions;For precision components, nickel or chromium electroplating coatings can be used to balance anti-discoloration and wear resistance.

 

(4) Full-Process Control During Processing

The anti-discoloration technology of titanium plates relies on full-process process control:

For high-temperature processes like forging and welding, water cooling and air cooling, they are used for real-time temperature reduction to control the surface temperature within a safe range and avoid excessive oxidation;

 

Processing personnel must wear clean gloves, regularly clean equipment and workbenches, and use dry and clean packaging for storage and transportation in order to prevent contamination by fingerprints, oil stains, and dust;

 

To detect the surface concentration of nitrogen, carbon, and hydrogen by glow discharge spectroscopy and control the oxide film thickness ≤30.0nm to ensure the protective effect.

 

Ruihang Group, a professional manufacturer of titanium and titanium alloy product, supply high-quality titanium plates,rings,forgings,bars, pipes and other non-ferrous metal products etc. For more details,please contact us via the Email:Sam.Rui@bjrh-titanium.com