Due to its excellent corrosion resistance, titanium rods generally do not undergo further surface treatment to enhance their corrosion resistance. However, in order to prevent comprehensive corrosion of titanium in non oxidizing acid aqueous solutions such as hydrochloric acid and sulfuric acid, as well as to prevent interstitial corrosion and pitting corrosion in NaCl aqueous solutions, surface treatment methods are sometimes used. Atmospheric oxidation treatment: Titanium is placed in a high-temperature atmosphere to thicken the oxide film, which increases with temperature and time. Atmospheric oxidation treatment is effective for both comprehensive and interstitial corrosion of titanium, and the method is relatively simple, but its durability is not very reliable. This is because atmospheric oxidation treatment only thickens the oxide film. In a corrosive environment, pure titanium's thickened oxide film becomes thinner over time, ultimately leading to corrosion. The duration of its corrosion resistance is determined by the atmospheric oxidation treatment conditions (T, t) and the severity of the corrosive environment, and it is difficult to predict this specific duration. This method is generally not used for components that require long-term stable operation.

The disadvantage of titanium is its poor wear resistance and the tendency to produce defects such as rough surfaces on the surface. Currently, it is difficult to apply to sliding mechanical components. We are currently actively researching and developing various surface treatment methods. The methods suitable for titanium surface treatment include wet coating method represented by Cr and Ni plating, thermal diffusion method, overlay welding method, and sputtering method. The more advanced methods recently are CVD, PVD, and PCVD surface strengthening method. 1. Wet coating: mainly using Cr and Ni-P plating methods, (it is difficult to directly coat Cr on titanium rods, usually Ni is plated first on titanium rods, and then Cr is plated. The electrolytic method has a fast film formation speed and a thickness of micrometers (decorative coatings are only 1um). It is an effective wear-resistant surface treatment method. 2. Thermal diffusion method: widely used for carburizing, nitriding, and boronizing processes in the hardening treatment of steel materials, and recently also applied to titanium. This article mainly introduces the difference between ion nitriding and gas nitriding. It uses glow discharge plasma to destroy the oxide film on the surface of titanium. Therefore, pre-treatment before nitriding does not require mechanical grinding or acid washing to remove the oxide film, and the nitriding efficiency is high. Titanium has good film resistance at 850 degrees, with a nitride film thickness increasing from 0.7um to 5.0um and a surface hardness of 1200-1600Hv. 3. Welding method: The use of plasma transfer arc for surface welding and hardening modification of titanium plates also has excellent wear resistance. The method is simple, and the processed material does not need to be exposed to the entire high temperature, which can prevent a decrease in mechanical properties, but requires secondary processing. Only applicable to handling thick large workpieces. 4. Sputtering method: A method of using plasma jet and high-speed air jet to spray the dropped molten metal onto the surface of the processed material, which does not require vacuum and can be processed in the atmosphere, resulting in high production efficiency. But the adhesion of the coating is not sufficient.

Precious metal coating: The corrosion resistance of titanium is maintained by the oxide film formed on the surface. The formation reaction of this oxide film is generally represented by the following equation: Ti+2H2O → TiO2+4H++4e. This reaction is an anodic reaction. Therefore, as long as the potential of titanium is increased, this reaction can be further directed to the right, which means that the stability and corrosion resistance of the titanium oxide film are improved. However, to increase the potential of titanium, it is necessary to use a counter electrode and apply a high voltage from the outside. At the same time, it is difficult to apply a uniform voltage when the area is large, so it is not often used. Generally, precious metals do not corrode in harsh environments and exhibit high potential. By utilizing this, coating precious metals on the surface of titanium causes the potential of titanium to shift towards the higher potential direction, thereby improving its corrosion resistance. Cheaper Pd, Ru, or their oxides (PdO, RuO2) are commonly used for titanium coating in precious metals. Coating precious metals or their oxides on titanium rods is effective in improving their corrosion resistance, and the corrosion resistance of the coated material can rival that of Ti/FONT>0.15Pd alloys. The disadvantage is that when used for a long time in fluids or fluids containing solids, the precious metal film will peel off from the titanium surface, although this peeling is rare. Currently, Japan is developing coating methods with good adhesion, but the cost is higher. Gas method, due to the need to heat at temperatures far above the phase transition point of titanium, causes changes in tissue and shape, resulting in products that cannot meet the requirements for use; CVD, PVD, and PCVD methods require special equipment and large-scale equipment that can be mass-produced is currently under development, resulting in high costs. These treatment methods are rarely used to improve corrosion resistance, and are sometimes used to improve wear resistance. Pb+and Pt+implantation methods (ion beam, electron beam) are very effective in improving corrosion resistance through surface modification by ion implantation, but the cost is higher and is currently under research and has not yet been put into practical use.