Because of its high specific strength, excellent corrosion resistance and biocompatibility, titanium and titanium alloys are widely used in aviation, aerospace, chemical industry, medicine and other fields. However, due to the high activity and easy oxidation of titanium and titanium alloys, the traditional preparation process (casting, electron beam welding and vacuum plasma spraying, etc.) must be protected by vacuum or inert gas, which undoubtedly increases the manufacturing cost. In recent years, the additive manufacturing technology has made tremendous progress. In the traditional additive manufacturing technology (laser additive, electron beam additive and arc additive), the powder or wire material undergoes a melting-solidification process, and the near-net-shaped parts , Opened a new direction for the manufacture of titanium and titanium alloys. However, the high-temperature process still brings metallurgical defects, such as micro-cracks, residual stress and deformation.
Cold spraying (Cold Spraying, CS) is a forming technology based on high-speed solid-state collision of micron particles (the bonding mechanism is similar to explosive welding, also known as micro solid phase welding), and has been discovered since the mid-1980s , Has been widely concerned by scholars at home and abroad. Its working principle is to introduce high-pressure gas (He, N2, air or their mixed gas) into a specially designed Laval nozzle, using high-pressure gas to accelerate the micrometer scale at a lower temperature (below the melting point of the sprayed material) The particles in the solid state hit the substrate at a high speed in the solid state, and the particles / substrate undergoes severe plastic deformation and is deposited on the surface of the substrate to form a coating. So far, cold spray technology can be used to prepare most metals and their alloys (Al, Cu, Ag, Mg, Sn, Zn, Ti, Ni, Fe, Ta, stainless steel, Ti6Al4V, high temperature alloys, high entropy alloys, etc.); Metal-metal composite materials (Al-Cu, Al-Ti, Al-Ni, W-Cu, etc.), metal-ceramic composite materials (Al-Al2O3, Al-SiC, Al-TiN, Ti-SiC, etc.); even non- Crystal (NiTiZrSiSn, Al-based, Fe-based, etc.), nano-structured metal materials (nano-Al, Ni, Cu), etc. In recent years, cold spraying has expanded from coating preparation to the field of forming, manufacturing and repairing and remanufacturing, that is, cold spraying solid additive manufacturing technology. As a new member of the additive manufacturing family, cold spray has shown great potential in the manufacturing industry, and has attracted the attention of important industrial fields worldwide.
As one of the representative materials, the high-quality cold spray forming of titanium and titanium alloys faces huge challenges and has attracted the attention of international peers. This article first systematically discusses the deposition characteristics of cold sprayed titanium and titanium alloy deposits and the influencing factors of the process. How are the particles deposited? What is the organization and performance of the deposit? Process parameters-organization-performance correlation? Secondly, existing research shows that the bonding mechanism of titanium and titanium alloys is very different from copper and aluminum, so understanding the bonding mechanism of titanium and titanium alloys becomes particularly important. Finally, the mechanical properties of titanium and titanium alloy deposits need to be improved. How to effectively improve the mechanical properties is another important problem. At present, improving the mechanical properties of titanium and titanium alloy deposits through compounding with other processing technologies is called "cold spraying compound technology".
The original link is as follows: https://www.sciencedirect.com/science/article/pii/S007964251930115X