Preparation of zinc oxide/poly-ether-ether-ketone (PEEK) composites via the cold sintering process

Appropriate preparation routes allow designing and improving the performances of ceramic-based functional composites. In this work, two powder-preparation methods enabled by the cold sintering process are utilized to fabricate unique ZnO-based varistor composites. The thermoplastic polymer, poly-ether-ether-ketone (PEEK), has been successfully integrated with ZnO to form dense ZnO-PEEK composites. With a dissolution method, PEEK particles can be homogeneously dissolved by the mixed solution of tetrahydrofuran and toluene and then form nanoscale thin grain boundaries after cold sintering process. In the direct mixing method, large PEEK particles are observed in the cold sintered samples. A Finite Element Method (FEM) analysis indicates that von-mises stresses concentrate at the grain boundaries of ZnO and at the interfaces of ZnO and PEEK, and these can be increased with the increase of PEEK particle sizes. The electrical properties have been improved with the addition of PEEK, and the cold sintered 95ZnO-5PEEK shows a high breakdown electric field (0.1 mA/mm(2)) of 3070 V/mm, and a nonlinear coefficient of 5. In addition, the conduction mechanism of the composites has been investigated using impedance spectroscopy. Overall, our work provides a strategy for the development of high-performance ceramic-polymer composites via cold sintering process. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Two powder-preparation methods enabled by the cold sintering process were utilized to fabricate unique ZnO-based varistor composites in this study, with successful integration of ZnO and PEEK. The addition of PEEK improved the electrical properties of the composites, as evidenced by a high breakdown electric field and nonlinear coefficient in the cold sintered samples. Impedance spectroscopy was used to investigate the conduction mechanism of the composites.