Effect of Amorphous Carbon Coating of Carbon Fiber on Mechanical Properties of Carbon Fiber Reinforced PA6
Journal of the Society of Materials Science Japan
Important concerns in Carbon Fiber Reinforced Thermoplastics (CFRTP) molding include resin impregnation into carbon fiber bundles and fiber matrix interfacial adhesion. Generally, thermoplastic resins have a higher viscosity at the time of molding than thermosetting resins, and it is difficult to impregnate matrix resin into a reinforcing fiber bundle. In addition, commercially available carbon fibers are normally coated with a sizing agent for epoxy matrix, compatibility with thermoplastic
... n is not necessarily good. Therefore, in order to improve the mechanical properties of CFRTP, it is important to develop a new method for improving the impregnation property and the fiber and matrix interfacial adhesion. In recent years, a method for coating the surface of carbon fiber with amorphous carbon has been developed. It has been reported that CFRTP laminates using amorphous carbon coated carbon fiber or amorphous carbon coated carbon fiber with silica particles as reinforcing fibers have high bending strength. The reason is considered to be the improvement in the interfacial adhesion between carbon fiber and thermoplastic resins by the amorphous carbon coating and the improvement in the impregnation property due to the maintenance of the spread state of carbon fiber bundle by silica particles. However, the influence of amorphous carbon and silica particles on the actual fiber matrix interfacial strength and impregnation characteristic has not been clarified. In this study, amorphous carbon coated carbon fibers with and without silica particles were used as reinforcing fibers; and the fiber matrix interfacial strength with PA6 were evaluated by single fiber pull-out test. In addition, the wettability of amorphous carbon coated plain woven carbon fiber with and without silica particles and the mechanical properties of their laminate were evaluated. By coating the carbon fiber surface with amorphous carbon, the fiber matrix interfacial strength is increased due to the increase of the oxygen-containing functional groups on the fiber surface. By coating the carbon surface with amorphous carbon, carbon fiber plain woven fabric has improved wettability with resin and addition of silica particles spreads fiber bundles and improves wettability. CF/PA6 laminates using amorphous carbon coated carbon fiber with silica particles have lower void content and higher flexural strength.