Application of laser cleaning technology in carbon fiber surface modification

Carbon fiber composites have been widely used in aerospace, wind power, automotive and other fields because of their light weight, high strength, corrosion resistance and fatigue resistance. Carbon fiber composites not only have high specific strength, high specific modulus and lightweight characteristics.

Moreover, carbon fiber composites have higher heat resistance, structural designability, fatigue resistance, corrosion resistance, vibration resistance and electromagnetic shielding capacity, which are more in line with the development trend of the industry.

Taking the new energy battery package box as an example, the material should have the characteristics of electrical insulation, high heat dissipation and chemical stability. The box is generally composed of upper and lower boxes and sealing system. The battery pack mass accounts for 18%~30% of the vehicle system mass, while the box mass accounts for about 10%~20% of the total battery pack mass. At present, metal is widely used as the battery pack body material, and composite materials are gradually paid attention to due to their excellent specific stiffness and strength. The composite materials used in the battery case are mainly carbon fiber composite, glass fiber reinforced composite, SMC composite and other lightweight materials. Carbon fiber reinforced composite has the advantages of low density, high stiffness and strength, and has been widely used in the battery case.

In the carbon fiber box, metal joints are often used at the connection between the box and the body, and the joint and the main structure layer of the material are bonded and fixed in a mixed way. The hybrid connection mode of "mechanical fixation+adhesive bonding" can also effectively improve the fatigue strength, torsional stiffness and crashworthiness of light components and body structures, and make the connection have good stability while lightweight.

In the process of carbon fiber bonding, it is often necessary to treat the bonding surface. For the surface treatment technology of carbon fiber composites, the traditional treatment method is developing towards the direction of high efficiency, intelligence and environmental protection. When the laser energy density is lower than the damage threshold of the carbon fiber material, the micro morphology of the material surface will not change; When the laser energy density is higher than the material damage threshold, the laser can melt, vaporize, decompose and remove the material, so as to form such micro morphologies as bulges, pits, porous sponge and periodic structures on the material surface.

Taking the carbon fiber of battery PACK upper cover of a car enterprise as the test object, the laser cleaning equipment is produced by Qiangyuan laser. The carbon fiber surface is cleaned by laser to increase the bonding capacity. Carbon fiber materials are provided by a carbon fiber supplier of a car enterprise.

In the cleaning process, the carbon fiber chip samples were initially cleaned. The effect is shown in the figure. After cleaning, use a dyne pen to test the surface tension value, and the results meet customer requirements.

Then the carbon fiber cleaning test of the shell was carried out. The test part was the battery PACK cover plate of a well-known automobile enterprise, which was used to evaluate the efficiency, equipment accessibility and other production process capabilities.

For carbon fiber surface cleaning technology, laser cleaning is a suitable choice. The cleaning process is environmentally friendly and green, with almost no pollutants and no consumption of consumables. High efficiency, the maximum cleaning efficiency can reach 20m2/h. For higher cleaning efficiency, it can be obtained by increasing the laser power. It is easy to realize automation. Due to the regularity of the battery PACK cover plate, the automatic cleaning of carbon fiber board can be easily realized by using a robot or a gantry plus a turnover platform and a blanking workbench.

Source: Intense far laser