Titanium alloys are widely used in aerospace, biomedical and other fields due to their light weight, high strength and corrosion resistance. However, the low surface hardness and poor wear resistance of titanium alloys limit their application in high friction environments. To improve the wear resistance of titanium alloys, a variety of surface coating techniques can be used.
1. Hypersonic flame spraying (HVOF)
The HVOF method is used to prepare different thicknesses of Cr3C2-NiCr, Ni50 and NiCr coatings on the surface of TC4 titanium alloy, and the Ni-cBN wear-resistant top layer is prepared on the bottom surface by composite plating technology, which can significantly improve the bonding strength and wear-resistant properties of the coating. The tribological properties of different coatings with TC4 titanium alloy under dry friction conditions were found by testing and analyzing the microstructure and mechanical properties of the coatings. It is found that Ni50 coating can reduce the adhesive wear loss of TC4 titanium alloy substrate and friction vice, which provides a feasible program for the design of wear-resistant coatings on the surface of titanium alloys and the improvement of friction performance between titanium alloy parts.
2.Laser cladding technology
Laser cladding can melt pre-sprayed or bonded powder material on the surface of titanium alloy to prepare wear-resistant and self-lubricating coatings, and the wear resistance of the coating can be effectively improved by adjusting the laser power, scanning speed, spot diameter and other process parameters. In addition, the addition of reinforcing and self-lubricating phases during the laser cladding process can further improve the microhardness and wear resistance of the coating. Commonly used cladding materials include hard ceramics and nickel-based self-fusing alloys. Studies have shown that the hardness and wear resistance of the coating after laser melting of SiC is significantly improved.
3. Micro-arc oxidation technology
Micro-arc oxidation can form a layer of dense oxide film on the surface of titanium alloy, which can significantly improve the wear resistance and corrosion resistance of titanium alloy by combining with other surface modification technologies. Micro-arc oxidation technology in titanium alloy surface preparation of ceramic layer, with low preparation temperature, simple equipment, solution environmental protection, film layer uniformity and density and other advantages. Through the micro-arc oxidation technology, a film layer with high hardness and high film base bonding strength can be formed on the surface of titanium alloy, which significantly improves the wear resistance and corrosion resistance.
4. Multi-phase, multi-level, multi-scale mixed reinforcement design
Inspired by nature's high-performance biological microstructure, the design idea of multi-phase, multi-level, multi-scale mixed reinforcement can be designed with high hardness, high toughness and good wear resistance of the coating.
5.Thermal Spraying Technology
Thermal spraying technology by heating the spray material to a flowable state and then accelerated splashing to the surface of the substrate, the formation of coatings with specific functions. This technology can improve the wear resistance of titanium alloys. Commonly used spray materials include nickel-coated graphite, monolithic metals and alloy materials.
6. Cold spraying technology
Cold spraying technology is a method of using high-speed gas to accelerate the powder material to a high speed and make it deform plastically when it hits the surface of the substrate to form a coating. This technology can be used to prepare wear-resistant coatings on the surface of titanium alloys, which has the advantages of strong coating bonding and low porosity.
7. Ion implantation technology
Ion implantation technology in a vacuum, low temperature, high-energy charged ions into the metal near the surface layer, the formation of a new surface modification of the alloy layer, the formation of the alloy layer and the substrate with a strong bonding force, with good wear-resistant effect.
8. Vapor Phase Deposition Technology
Vapor phase deposition can form a layer of uniform coating on the surface of titanium alloy, by adjusting the composition and structure of the coating, it can effectively improve the wear-resistant properties of titanium alloy.
9.Self-lubricating composite coating
Researchers have also prepared self-lubricating composite coatings on the surface of titanium alloys, which contain hard reinforcing phases and lubricating phases, such as TiN, TiMo, Ti-Ni, and MoS2, TiS, these coatings can provide self-lubricating properties while improving wear resistance.
10. High entropy alloy high temperature coatings
High-entropy alloy high-temperature coatings have many excellent properties, which can be further optimized by adjusting the content of one or more of these elements, and therefore have extremely promising applications. However, this kind of coating is still in the laboratory research stage, need to solve the element ratio is unreasonable and the matrix elements of the melt cladding layer of the reaction and other issues.
