16/02/2023
Research progress on surface enhancement technology of titanium and titanium alloys
1、Nanoscale surface treatment As a new type of surface treatment technology, nanoscale treatment can achieve deep refinement of the grains at the material's processing location on the surface of titanium and titanium alloys through physical, chemical, and other means without changing the material composition, until it reaches the nanoscale level. This fundamentally solves the problem of surface fatigue resistance and improves the corrosion resistance of titanium and titanium alloys. It can also improve wear resistance in practical applications. Using methods such as supersonic particle bombardment, the processing tool interacts with the surface of the workpiece, breaking the titanium and titanium alloy surface grains by mechanical means, and strengthening the surface after deep refinement. By using high-energy shot peening surface nanoscale technology on GR5, the grain size can be close to 20nm, and the material's fatigue resistance can be improved by the hardening layer with a higher surface hardness than the raw material. After processing GR2, the nanoscale surface layer with a grain size close to 30nm can enhance the material's hardening degree of deformation twinning. Especially in the treatment of titanium and titanium alloys at 623K, China is ahead of the United States in relevant specifications and currently leads the industry. By using supersonic particle bombardment, Ti-6Al-4V alloy can be treated, and a nanoscale equiaxed structure with a grain size of 20nm can be derived on its surface, which can increase the surface hardness of the alloy by more than twice compared to the raw material.
2, Surface Diffusion and Ion Implantation
Unlike surface nanocrystallization, surface diffusion and ion implantation involve doping metal or non-metal materials into a titanium alloy substrate, changing its surface composition, and using modified layers to improve the surface resistance of the titanium alloy substrate, or using metals such as aluminum and molybdenum for diffusion to enhance the wear resistance and corrosion resistance of the titanium alloy substrate. By using a mesh cathode glow discharge method to coat Ta on the surface of the TC4 substrate, the corrosion resistance of the TC4 substrate can be effectively improved. By using a solid powder embedding method and preparing a molybdenum-diffused layer, the surface phase structure of TC6 can be significantly changed, and the surface hardness of TC6 can be increased to 1400HV. Currently, with the rapid development of science and technology, the theoretical research and functional use of vacuum technology are also gradually improving, which can derive an ion implantation technology based on the existing surface pe*******on technology. For example, by using the ion nitriding method, the surface hardness of TA7 titanium alloy can be increased to 1200HV. Using the arc glow ion hydrogen-free carbon diffusion technology to treat the surface of Ti6AI4V alloy can achieve a surface hardness of 935HV and also exhibit strong wear resistance. The liquid-phase plasma electrolytic carbon-nitrogen co-diffusion technology can also be used to treat Ti6Al4V alloy, producing a hard Ti-deposited coating on the alloy surface. Increasing the processing time of titanium alloy with this method can effectively increase the thickness of the diffusion layer and improve the wear resistance of the titanium alloy.
3、Surface coating technology
By using corresponding processes on the surface of the substrate material, a protective coating is formed on the surface of the substrate material through composite coating, which has good performance in chemistry, thermology, and other aspects. Surface coating technology can effectively improve the performance of titanium alloys by using the corrosion resistance and heat resistance of the coating, and also has a relatively long service life in subsequent use. Currently, surface coating technologies such as v***r deposition and thermal spraying can effectively improve the wear resistance of titanium alloys and have a good effect on corrosion resistance. By integrating surface activation and hydrogenation treatment, the conductivity of the titanium alloy surface can be effectively improved, and material corrosion problems can be avoided when in contact with soft rainwater and other substances. By using v***r deposition technology, TiAIN film can be formed on TA2 and TC11 substrates, which can form a metallurgical bond between the film layer and the substrate part with three elements combined, effectively enhancing various properties of the substrate material.
