Enhanced bonding strength of AZ31B/carbon-fiber-reinforced plastic laminates by anodization treatment in a saturated Na2SiO3 solution

Surface treatment of the metal substrate plays a critical role in improving the bonding performance of fiber metal laminates. In this work, we use a saturated Na2SiO3 solution to fabricate an anodized film on an AZ31B substrate by an anodizing process and achieve enhanced bonding strength between the AZ31B substrate and carbon-fiber reinforced plastic (CFRP) composites. The results indicate that the primary breakdown voltage of anodization is reduced to approximately 35 V in the saturated Na2SiO3 solution. The film presents a porous/linear texture composite structure after anodizing for 2 min, and the porous structure is composed of micro-and nano-pores. The bonding strength of the AZ31B substrate anodized for 2 min/CFRP laminate reaches 15.96 MPa, which is 106% higher than that of the uncoated sample. The enhanced bonding strength is mostly attributed to the mechanical interlocking effect caused by the micro-and nano-pore composite structure. With anodizing time prolonged to 30 min, the surface roughness of the substrate obviously increases, but larger pores and gaps form in the film, resulting in a lower film strength and thus a lower bonding strength.

Automated summary

The surface treatment of the metal substrate is crucial in improving the bonding performance of fiber metal laminates. In this study, an anodized film is fabricated on an AZ31B substrate using a saturated Na2SiO3 solution, resulting in enhanced bonding strength between the substrate and carbon-fiber reinforced plastic (CFRP) composites. The porous/linear texture composite structure of the film, which is composed of micro-and nano-pores, is primarily responsible for the improved bonding strength.