Laser coating technology refers to the placement of selected coating materials on the surface of the coated matrix in different ways of feeding. The hardness of the coating layer is obviously reduced, the metal laser cutting machine is simultaneously melted with a thin layer on the surface of the substrate by laser radiation. There is little influence on the hardness of cladding, The preheating temperature is high, so that the heat dissipation is relatively slow, and the temperature ladder of the coating layer is reduced.
The dilution rate of the coating decreases with the increase of spot competition, and the surface coating with the low dilution degree and the metallurgical geometry of the substrate is formed after the rapid solidification, so as to significantly improve the wear resistance, corrosion resistance, heat resistance, oxidation resistance and electrical properties of the surface of the matrix material. Therefore, under certain conditions of laser cutting machine power, when the scanning speed and spot competition are certain, the preheating temperature is lower, which is because the temperature of the matrix is closer to the coating temperature after preheating, and the laser energy absorbed by the molten pool is reduced, and the surface temperature of the molten pool decreases with the decrease of the laser energy absorbed by the molten pool.
The approximate linear relationship between the increase of power and the sound of temperature is higher, which shows that with the increase of power, the greater the laser energy obtained in the molten pool, the higher the natural sound of temperature. Spot diameter, powder feeding speed, scanning speed and so on, they have a great impact on the dilution rate of the coating layer, crack, surface roughness and the tightness of the covered parts. Scanning speed is too fast, easy to make the powder not completely melted, resulting in splashing phenomenon, affecting the quality of the coating. With the increase of scanning degree, the cooling rate of liquid metal in molten pool also increases. What should be the place of burr in laser cutting machine.
Laser cladding is a complicated physical, chemical metallurgical process, and the greater the power of metal laser cutting machine, the more likely the porosity is to be produced, the parameters in the coating process have a great influence on the quality of the coating. So that the nucleation does not have enough time to grow up in the subsequent solidification process, and preheating can change this temperature difference, so the temperature drop rate at the melting point is less than that without preheating, so with the increase of scanning degree, the grain in the coating layer decreases obviously, and the hardness increases accordingly.
These effects can be reflected in the temperature change of the molten pool, and the larger the heating of the substrate is, the more serious the surface layer will fall into the collective and form a deeper groove; the low power, the powder can not be completely melted, the wettability of the melt and the substrate is reduced, the surface tension is too high, resulting in melt condensation, and may also produce bead-like results.