The surface treatment technology of titanium wire carburizing forms a hardened layer of titanium carbide (TiC) through carbon atom diffusion, significantly improving the wear resistance and hardness of the material. The following is a summary of the main methods and technical points:
1、 Common carburizing methods
1. Solid carburizing
Direct contact between carbon powder and titanium wire is used for reaction in high-temperature vacuum or argon methane environment.
The process is simple and cost-effective, but strict control of oxygen content is required to avoid interference of oxide film with carbon diffusion.
2. Gas carburizing
Using methane or propane as carburizing gas, a dense and highly adhesive TiC layer is formed in an inert atmosphere.
The TiC layer generated from methane has higher hardness, while propane enhances wear resistance but has lower hardness.
3. Ion carburizing
Using an electric field to accelerate carbon ion bombardment on the surface of titanium wire in a vacuum environment, promoting deep diffusion, suitable for complex shaped workpieces.
It needs to be equipped with a source electrode (carbon material) and a dual power supply system to achieve low-temperature and high-efficiency carburizing.
4. Laser carburizing
By locally heating the surface of titanium wire with high-energy laser and injecting carbon source, rapid selective hardening can be achieved with high precision but high equipment cost.
2、 Key process parameters
Temperature control: The temperature range is 950-1020 ° C. If it is too high, it can easily cause the TiC layer to crack, while if it is too low, the diffusion efficiency will be insufficient.
Atmosphere management: Inert gas or vacuum environment is required to avoid oxygen interference with carbonization reaction.
Carburizing time: usually 2-6 hours, layer thickness controlled at 50-150 μ m, too thick is prone to peeling off.
3、 Processing effect and limitations
Surface hardness: The TiC layer hardness can reach 2700-8500MPa, and the wear resistance is improved by 3-5 times.
Layer thickness characteristics: The depth of the carburized layer is better than that of the nitrided layer, but brittleness increases with increasing thickness, requiring a balance between hardening and toughness.
Hydrogen residue risk: Gas carburizing may introduce hydrogen, requiring subsequent vacuum annealing dehydrogenation.
4、 Precautions
Oxygen content monitoring: The oxygen partial pressure should be below 10 ⁻ Pa, otherwise the oxide film will hinder the penetration of carbon atoms.
Layer thickness optimization: In industrial applications, it is recommended to have a layer thickness of ≤ 100 μ m to balance performance and reliability.
Post processing requirements: After carburizing, slow cooling or quenching is required to stabilize the structure and avoid cracking caused by thermal stress.
Summary: Through the above methods, titanium wire can be widely used in aerospace and other high wear resistant scenarios.