Laser cladding is a new type of coating technology. It is a high-tech technology involving light, mechanics, electricity, materials, detection, and control. It is an important supporting technology for advanced laser manufacturing technology and can solve problems that traditional manufacturing methods cannot complete. It is a high-tech technology supported and promoted by the state. At present, laser cladding technology has become one of the important means for the preparation of new materials, rapid and direct manufacturing of metal parts, and green remanufacturing of failed metal parts. It has been widely used in aviation, petroleum, automobiles, machinery manufacturing, shipbuilding, and mold manufacturing. and other industries. In order to promote the industrialization of laser cladding technology, researchers from all over the world have conducted systematic research on the key technologies involved in laser cladding and have made significant progress. There are a large number of research, conference papers, and patents at home and abroad introducing laser cladding technology and its new applications: including laser cladding equipment, materials, processes, monitoring and control, quality inspection, process simulation and simulation, etc. But so far, laser cladding technology cannot be applied industrially on a large scale. Analyzing the reasons, there are factors such as government-oriented factors, limitations on the maturity of laser cladding technology itself, and the degree of recognition of laser cladding technology by all sectors of society. Therefore, in order to achieve a comprehensive industrial application of laser cladding technology, we must increase publicity, be guided by market demand, focus on breaking through the key factors that restrict development, and solve the key technologies involved in engineering applications. I believe that in the near future, The application fields and intensity of laser cladding technology will continue to expand.

Here are a few application examples of laser cladding: the focused power density of the laser beam can reach 1010~12W/cm2, and the cooling rate of the material can be as high as 1012K/s. This comprehensive characteristic not only provides opportunities for the growth of new disciplines in materials science. It provides a strong foundation and an unprecedented tool for the realization of new materials or new functional surfaces. The melt created by laser cladding is far away from the equilibrium state of rapid cooling conditions under high-temperature gradients, resulting in the formation of a large number of supersaturated solid solutions, metastable phases, and even new phases in the solidification structure, which has been confirmed by a large number of studies. It provides new thermodynamic and kinetic conditions for fabricating functionally graded in-situ autogenous particle-reinforced composite layers. At the same time, the preparation of new materials by laser cladding technology is an important basis for the repair and remanufacturing of failed parts under extreme conditions and the direct manufacturing of metal parts. It has received great attention and multi-faceted research from the scientific community and enterprises around the world. At present, laser cladding technology can be used to prepare iron-based, nickel-based, cobalt-based, aluminum-based, titanium-based, magnesium-based, and other metal matrix composite materials. Functionally classified: coatings with single or multiple functions can be prepared, such as wear resistance, corrosion resistance, high-temperature resistance, etc., as well as special functional coatings. From the perspective of the material system that constitutes the coating, it has developed from a binary alloy system to a multi-component system. The alloy composition design and multifunctionality of multi-component systems are important development directions for the preparation of new materials by laser cladding in the future. New research shows that steel-based metal materials dominate my country’s engineering applications. At the same time, metal material failures (such as corrosion, wear, fatigue, etc.) mostly occur on the working surface of parts, and the surface needs to be strengthened. In order to meet the service conditions of the workpiece, using large pieces of in-situ self-generated particle-reinforced steel-based composite materials not only wastes material but is also extremely costly. On the other hand, when examining natural biomaterials from the perspective of bionics, their composition is dense on the outside and sparse on the inside, and their properties are hard on the outside and tough on the inside. Moreover, density-sparse, hard-toughness changes in a gradient from the outside to the inside. The properties of natural biomaterials The special structure makes it have excellent performance.

According to the special service conditions and performance requirements of engineering materials, there is an urgent need to develop new surface metal matrix composite materials with strong and tough combinations and gradient performance. Therefore, using laser cladding to prepare gradient functional in-situ self-generated particle-reinforced metal matrix composites that are metallurgically bonded to the substrate is not only an urgent need for engineering practice but also an inevitable trend in the development of laser surface modification technology. Laser cladding technology has been reported to prepare in-situ autogenous particle-reinforced metal matrix composites and functionally graded materials, but most of them remain at the stage of structure and performance analysis, control of process parameters, size, spacing, and volume ratio of the reinforcement phase It has not yet reached a controllable level. The gradient function is formed through multi-layer coating, and there is inevitably a problem of weak interface bonding between layers. There is still a long way to go before practicality. Using laser cladding technology to prepare metal-based surface composite materials with controllable particle size, quantity, and distribution, appropriately matched strength and toughness, and integrating gradient functions and in-situ self-generated particle reinforcement is an important development direction in the future. The research content involves:

1. The technology, means and principles of cladding material composition, structure and performance design and the control technology for process implementation.
2. Establishment of thermodynamic and kinetic models for particle reinforcement phase precipitation, growth and strengthening of functionally graded autogenous particle-reinforced metal matrix composites prepared by laser cladding.
3. .Particle-reinforced phase morphology, structure, function and composite bionic design and control technology of size, quantity and distribution.
4. Research on the principles, key factors and process methods of coating composition, structure and performance gradient control.
5. Observation, analytical control, and characterization of macro and micro interfaces; analysis and detection of conventional properties of functionally graded in-situ particle-reinforced metal matrix composites, as well as wear behavior and failure mechanisms under different working conditions. Breakthroughs in these research contents may solve the problem of mismatch in compatibility between coating and substrate and prone to cracks, and promote the expansion of the application field of laser cladding technology.