Research on Laser Cutting Technology of High Hardness and Brittle Inorganic Nonmetallic Materials
In terms of processing technology, the first step in processing high-hardness and brittle inorganic non-metallic materials must determine a reasonable laser output method. Compared with metal materials, in addition to the universal characteristics of high hardness and brittleness, and poor thermal conductivity, non-metallic materials of high-hardness and brittle inorganic non-metallic materials also have obvious personality differences. There are differences in the microstructure due to different times. This difference is often not negligible for non-destructive cutting. In practice, researchers often need to make process adjustments, improvements, and even innovations depending on the specific conditions of the processed materials. The details of pretreatment required before material processing, such as infiltration, adhesion of adhesive films that help stress release, etc., are also the same. Can not be ignored. Therefore, cutting high-hardness and brittle inorganic non-metallic materials with high-efficiency non-destructive laser cutting machines has always been an attractive and urgent problem to be solved. Using laser as a processing energy, the development potential in the processing of hard and brittle, high-hard and brittle inorganic non-metallic materials has been revealed: it can realize non-contact processing and reduce the damage caused by contact stress to high-hard and brittle inorganic non-metallic materials. ; High hardness and brittle inorganic non-metallic materials have a high absorption rate for lasers (the high absorption rate of oxide high hardness and brittle inorganic non-metallic materials for 10.6 u0026 mu; m wavelength lasers can reach more than 80%), and the focused high-energy laser beam The energy in the local area of u200bu200bthe high hard and brittle inorganic non-metallic material can exceed 108 J/cm2, and the material can be melted and evaporated in an instant to achieve high-efficiency processing; due to the small focus spot, the heat-affected zone generated is small, which can meet the requirements of precision processing ; The laser's low electromagnetic interference and easy-to-guide and focus characteristics facilitate the realization of special processing requirements for three-dimensional and special-shaped surfaces. There are many types of lasers. Measured by the quality of the laser beam, the high absorption efficiency of the material to the heat source, and the standards that meet the needs of industrial development, CO2 laser thermal processing is still the main method for cutting high-hardness and brittle inorganic non-metallic materials. Recently, the Laser Engineering Research Institute of Beijing University of Technology adopted a 3.5 kW Slab CO2 laser to achieve the non-destructive cutting of high-density ceramic thick parts such as Al2O3 and SiC with a thickness of up to 10mm through the new process of laser discrete through-hole close-packed nondestructive cutting. However, the processing damage will become more serious with the increase of the thickness of high-hardness and brittle inorganic non-metallic materials. Crack suppression is a big problem that needs to be solved in laser cutting of thick, high-hard and brittle inorganic non-metallic materials. As shown in Figure 1, the cutting path includes various free paths of inner and outer contours such as straight lines, curves, and angles. Laser cutting technology has always been popular because of its non-contact, flexibility, high efficiency and easy realization of digital control. People hope that this high-energy beam processing method can be as good as the cutting of metal materials. Complete the non-destructive cutting of high-hardness and brittle inorganic non-metallic materials. Compared with metal materials, even high-density, high-hardness and brittle inorganic non-metallic materials have poor microstructure uniformity, which seriously reduces the thermal shock resistance of the material, and the deformation resistance to shear stress at room temperature is very large. It is easy to form cracks, chippings and even material fragmentation. Applied in the field of mechanical engineering, the material thickness of the non-metallic parts of high-hardness and brittle inorganic non-metallic materials is mostly more than 1mm, mostly several mm or even more than ten mm, thick plate materials, thick high-hardness and brittle inorganic non-metallic materials The processing often does not require high cutting precision. The difficulty of laser cutting is determined by the thermophysical properties of the material. Since most of the high-hard and brittle non-metallic materials are combined by covalent bonds, ionic bonds or a mixture of chemical bonds between the two, the chemical bonds between crystals have strong directionality, so they have Intrinsic characteristics of high hardness and high brittleness. Usually continuous output is suitable for amorphous non-metallic materials such as glass and organic glass, while pulse output is mostly suitable for polycrystalline or single crystal materials such as high-hardness and brittle inorganic non-metallic materials. In addition, thickness, density, etc. undoubtedly also need to be considered Important influencing factors.