Crystal-Orientation Control for Improving Adhesion and Wettability at PEEK-Resin/Al₂O₃ Interface

抄録

The adhesion strength and wettability at the interfaces between a polyetheretherketone (PEEK) resin and aluminum oxide (Al₂O₃), which have become more and more important for direct joining of PEEK resin and aluminum (Al), is investigated by using molecular simulations. Especially, the dependence of the adhesion strength and wettability on crystal orientations of sapphire Al₂O₃ were focused on to realize strong joint between the PEEK resin and Al₂O₃. By placing a PEEK-resin sphere on a sapphire Al₂O₃ surface and by heating the system to 650 K, the contact angles at the interfaces were calculated to evaluate the wettability. After the system is cooled to 300 K from 650 K, the adhesive fracture energy is calculated to evaluate the adhesion strength. The results of the contact angles showed that PEEK resin on the Al₂O₃ (10-10) and that on the Al₂O₃ (11-20) surface have low wettability with large contact angles. On the other hand, PEEK resin on the Al₂O₃ (0001) surface has high wettability with a small contact angle. The results of the adhesive fracture energies showed that the adhesion at the PEEK-resin/ Al₂O₃ (10-10) and PEEK-resin/ Al₂O₃ (11-20) interfaces are weak. On the other hand, the adhesion at the PEEK-resin/ Al₂O₃ (0001) interface is extraordinarily strong. To clarify the reason that the higher wettability and higher adhesion strength are obtained at the PEEK/Al₂O₃ (0001) interface, atomic configurations were visualized. The atomic configuration showed that the lattice-matched coherent interface and high surface atomic density is realized only at the PEEK/Al₂O₃ (0001) interface. Therefore, the lattice matching and the high surface atomic density at the PEEK/ Al₂O₃ (0001) interface are considered to be dominant factors in the high wettability and strong adhesion. The experimental results show that the wettability and critical load of scratch tests increase in the order: PEEK/Al₂O₃(10-10)< PEEK/Al₂O₃(11-20)<< PEEK/Al₂O₃ (0001).