First, mechanical polishing is one of the commonly used techniques to improve surface quality. The surface of graphite product processing is polished step by step by using polishing sandpaper or polishing wheels of different grits. The processing marks and surface defects are removed starting from the coarse grit, and the surface roughness is continuously reduced as the grit becomes finer. For example, the surface can be gradually smoothed by using 200-mesh sandpaper for preliminary polishing and then changing to 400-mesh, 800-mesh, etc. This method is relatively simple to operate, but the efficiency is low and the operator's skills are required to be high.
Chemical mechanical polishing is also an effective technique. It combines the effects of chemical corrosion and mechanical grinding. A specific chemical polishing liquid is used to react chemically with the graphite surface to produce a softer product, which is then removed by the mechanical action of the polishing pad. This method can achieve very low surface roughness and is suitable for graphite product processing with extremely high surface quality requirements, such as the application of graphite electrodes in high-precision electrochemical machining. However, the selection and treatment of chemical polishing liquids need to be cautious to avoid environmental pollution.
In terms of characterization methods, roughness meter is a commonly used tool. It measures the vertical displacement change of the stylus by passing the stylus across the surface of graphite product processing, thereby obtaining the surface roughness value, such as Ra (arithmetic mean roughness), Rz (microscopic unevenness ten-point height) and other parameters. These parameters can intuitively reflect the smoothness of the surface and provide a quantitative basis for evaluating the polishing effect.
Atomic force microscopy can provide more microscopic surface information. It uses the interaction force between atoms to detect the atomic-level morphology of the graphite surface, and can clearly show the microscopic defects, grain boundaries and atomic arrangement of the surface. This is of great significance for studying the physical and chemical properties of the graphite surface and further optimizing the polishing process.
In addition, optical microscopes can be used to observe larger-scale defects and scratches on the surface of graphite product processing. By magnifying a certain multiple, the surface problem area can be quickly located, and the deficiencies in the polishing process can be assisted in judging so as to adjust the process in time.
Scanning electron microscopy (SEM) can provide high-resolution surface morphology images with a large depth of field. It can observe the structural features of graphite surfaces at different heights, which is very helpful for analyzing the microstructural changes on the surface and the material removal mechanism during polishing.
Through the rational application of a variety of surface quality improvement technologies and comprehensive evaluation with the help of different characterization methods, the surface quality of graphite product processing can be effectively improved, meeting the requirements of different application scenarios for the surface performance of graphite product processing, and promoting the further application of graphite product processing in high-end fields.
