Laser surface nanocrystallization technology includes surface material grain nanocrystallization and realization of surface nanostructures. Nano-materials and nanostructures have a variety of excellent performance has been gradually recognized, for metal materials, if the grain size to nano-scale, the overall performance will be greatly improved, while the metal surface of the nano-pattern Structure can greatly improve the surface properties of materials, can make the material with anti-oxidation, wear resistance, corrosion resistance, super-hydrophobic and a series of excellent performance.
There are a variety of methods for surface nanocrystallization of materials. There are a large number of surface nanocrystallization technologies. It is a surface layer which can realize the nano-characteristics by means of laser surface treatment technology and nanometer technology. It can be collectively referred to as green laser pointer surface nanocrystallization technology; More generally referred to as laser nano-surface engineering technology, is directly or mainly the use of laser this specific technical means to directly change or add material to change the surface of the solid material is treated, the composition or structure, so that the formation of nano-crystal Grain or a certain nanoparticle composition of the surface layer. Or the use of laser etching, laser embossing, laser hair, laser micro-nano modeling and other means to achieve nano-structure on the surface of the material.
After the successful development of the high-power laser in the 1970s, the laser surface treatment technology has been put into practical application, and then the laser quenching (laser phase transformation hardening surface modification technology), laser remelting, laser surface alloying, Laser cladding, laser surface amorphization and laser impact strengthening and other methods. These laser surface treatment technology through the surface of the material to form a certain thickness of the treatment layer to improve the mechanical properties of the material surface, metallurgical properties, physical properties, thereby improving the parts, the workpiece wear, corrosion resistance, fatigue and other properties. Laser due to high power density, good direction, easy energy transfer, can be transmitted in a variety of transparent media and other characteristics. At the same time, the development of red laser pointer pulse nanometer pattern is more feasible.
With the development of nano-materials and nano-surface engineering technology, the application of various laser surface treatment technology to achieve the surface of nano-exploration of the surface has gradually started, and achieved some results. Laser surface nanocrystallization technology is essentially a combination of laser surface treatment technology and nano-surface technology, so it also has all the advantages of laser surface treatment, compared to other surface nano-technology, these advantages are essential; Such as mechanical grinding surface nano-technology, it is not suitable for large area, complex shape parts; such as surface roll or vibration shot peening surface nano-technology in dealing with complex shape parts are difficult, the actual production is difficult to achieve, and Laser surface nano-technology is basically no similar problems.
Laser irradiation surface treatment research focused more on the surface hardening of laser pointer hardening work, but also in the laser solid solution or laser annealing on a lot of research, there is no researchers have made it clear that the use of laser irradiation metal Research on Nano - Surface of Parts. Laser remelting generally refers to the use of high-energy focused laser beam to melt the surface of the parts without any other ingredients to the surface of the rapid melting and solidification of grain refinement, to eliminate defects, to achieve the purpose of surface tissue improvement.
Laser cladding, also known as laser cladding or laser welding, laser irradiation and laser remelting are all directly processed without adding other materials, but laser cladding is achieved by adding a clad material to the substrate surface and using high Energy density of the blue laser pointer beam, so that with the substrate surface layer of the method of melting together, in the formation of the substrate surface with its metallurgical combination of filler coating. Laser cladding surface nanocrystallization technology can be divided into three main aspects, the first aspect is the use of similar laser remelting surface nano-method, take appropriate measures directly in the laser cladding process to make the deposited layer of nanocrystalline structure.
The application of surface treatment technology has a long history, but the surface engineering technology from concept to development into a complete discipline system time, and now only a few decades, laser technology and nano-technology and surface engineering technology combined with violet laser pointer surface nano-technology or Also known as laser nano-surface engineering technology. Although the use of a variety of laser surface treatment technology, such as laser irradiation, laser remelting, laser cladding and laser shock, has a lot of research data and achieved fruitful results, but specifically targeted for the use of these technologies, The research on surface nanocrystallization is still relatively small and not systematic, and the development of nano-patterning of laser surface is still in the early stage, so there is still a lot of research work in this field.