Introduction of laser cladding and laser cladding technology

Laser cladding is a surface modification technique, also known as laser cladding or laser cladding. Laser cladding forms an additive cladding layer that is metallurgically bonded to the surface of the substrate by adding a cladding material to the surface of the substrate and fusing it with a thin layer of the substrate surface with a high energy density laser beam.     

Specifically, the laser cladding technique refers to placing a selected coating material on the surface of the substrate to be coated by different irradiation methods to be simultaneously irradiated with a thin layer of the substrate surface by laser irradiation, and rapidly solidified to form a dilution. The surface coating with extremely low degree and metallurgical bonding with the substrate significantly improves the wear resistance, corrosion resistance, heat resistance, oxidation resistance and electrical characteristics of the surface of the substrate, thereby achieving the purpose of surface modification or repair, which satisfies The specific performance requirements of the material surface save a lot of valuable elements.

Laser cladding technology is a highly economical new technology that can produce high performance alloy surfaces on inexpensive metal substrates without affecting the properties of the substrate, reducing costs and saving valuable rare metal materials. Compared with surfacing, spraying, electroplating and vapor deposition, laser cladding has the characteristics of small dilution, compact structure, good coating and matrix bonding, suitable for cladding materials, large changes in particle size and content, and good controllability. , can realize three-dimensional automatic processing and high processing quality. Therefore, the application prospect of laser cladding technology is very broad, and the research and application of laser cladding technology are highly valued in various industrial advanced countries in the world.

Laser cladding process

  • According to the supply method of the cladding material, the laser cladding process can be roughly divided into two categories, namely, preset laser cladding and synchronous laser cladding.
  • Pre-set laser cladding is to place the cladding material on the surface of the substrate at the cladding surface, and then use the laser beam to scan and melt. The cladding material is added in the form of powder, silk and plate, and the powder is the most Commonly used.
  • Synchronous laser cladding is the direct feeding of the cladding material into the laser beam, so that the feeding and cladding are completed simultaneously. The cladding material is also mainly fed in the form of powder, and some are also fed by wire or plate.
  • The main process flow of the preset laser cladding is: pretreatment of the substrate cladding surface—pre-cladding material—preheating—laser melting—post-heat treatment.
  • The main process flow of synchronous laser cladding is: pretreatment of substrate cladding surface—feeding laser melting—post-heat treatment.
  • According to the process flow, the processes related to laser cladding are mainly substrate surface pretreatment methods, cladding material supply methods, preheating and post heat treatment.

Laser Cladding Equipment

The lasers used in laser cladding mainly include CO2 lasers and solid-state lasers (mainly including disc lasers, fiber lasers and diode lasers. Old-fashioned lamp-pumped lasers have gradually faded out due to low photoelectric conversion efficiency and cumbersome maintenance). For continuous CO2 laser cladding, domestic and foreign scholars have done a lot of research. The development of high-power solid-state lasers is rapid, mainly used for surface modification of non-ferrous alloys. According to reports in the literature, the laser cladding of aluminum alloy is carried out by CO2 laser, and the aluminum alloy matrix is easily deformed or even collapsed under the condition of CO2 laser irradiation. Solid-state lasers, especially disc lasers, have an output wavelength of 1.06 μm, which is one order of magnitude smaller than the CO2 laser wavelength, making them more suitable for laser cladding of such metals.