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Four major "black technologies" for titanium surface treatment

Titanium alloys have demonstrated irreplaceable application value in the fields of aerospace, biomedical, and high-end equipment due to their lightweight, high strength, and corrosion resistance. But it also has fatal shortcomings: poor wear resistance, easy adhesion to metal, and a monotonous silver gray surface. To overcome these drawbacks of titanium and titanium alloys, surface treatments such as electroplating, micro arc oxidation, electrophoretic coating, and anodizing are often required.
One Electroplating: Wearing "protective clothing" on titanium metal
Principle:
Like painting metal, electroplating a layer of metal film on the surface can prevent rust, wear, and make it look more beautiful.
Function:
1. Wear resistance: Nano pure nickel is plated on the surface of Ti6Al4V titanium alloy, resulting in increased hardness and wear resistance;
2. High temperature anti sticking technique: After silver plating on titanium blades, they will not "weld" together even under high temperature of 500 ℃, which solves the "biting problem" of aviation engines.
Difficulty: Titanium is too prone to making friends with oxygen, and there is always a layer of oxide film on the surface, which can cause trouble during electroplating.
Solution:
1. Add an activator to the nickel sulfate electrolyte, first use an electric pulse to "activate" the titanium surface, and then nickel plating.
2. Corrosion of titanium surface with hydrofluoric acid+dimethylformamide solution, and direct copper plating can also adhere firmly.
II Micro arc oxidation: allowing ceramic armor to grow on the surface of titanium
Principle:
A layer of ceramic film is "burned" on the surface of titanium by high-voltage electric spark, mainly composed of titanium oxide.
Function:
1. The ceramic film and titanium substrate bite together like tree roots piercing into the soil, and will not fall off even when pressed to 200 megapascals with a hydraulic press.
2. The film thickness is several hundred microns, as hard as ceramics, corrosion-resistant, wear-resistant, and heat-resistant.
Customized gameplay:
Adding potassium permanganate to the electrolyte can create a titanium film that is both corrosion-resistant and antibacterial!
III Electrophoretic coating: give titanium metal a "colorful bath"
Principle:
Put titanium parts into charged paint water, and paint particles will "line up" and attach to the surface to form a paint film.
Advantages:
1. Non toxic, water-soluble, and more environmentally friendly than traditional spray painting.
2. High degree of automation, 90% of car bodies use this method to apply primer.
3. Good biocompatibility, such as TA4 titanium alloy coated with polyurethane, can be used in the medical field.
Little knowledge:
Cathodic electrophoresis is more powerful than anodic electrophoresis, with stronger anti-corrosion and coverage capabilities.
4 Anodizing: Engraving "Nano Fingerprints" on Titanium Metal
Principle:
Equivalent to performing 3D printing reverse operation on metal, titanium serves as the anode and is electrified, resulting in the growth of an oxide film in the electrolyte, which can be divided into two forms:
1. Dense type: tens to hundreds of nanometers thick, smooth and dense, with good biocompatibility, suitable for anti-corrosion and medical use.
2. Multi porous: TiO ₂ nanotube arrays can grow in fluorinated electrolytes, arranged like countless nanostraws.
Magical application:
1. The nanotubes have a large specific surface area and can be used as photocatalytic materials (for decomposing pollutants) and solar panels.
2. Make a hydrogen sensitive sensor that is highly sensitive to hydrogen gas, with fast and stable response.
3. Used in lithium batteries to prevent corrosion and improve charging and discharging efficiency.

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