## 1 Introduction  
Polyetheretherketone (PEEK) is a high-performance engineering plastic that is chemically stable, heat-resistant, biocompatible with human tissues, and highly resistant to abrasion, which has led to its widespread use in medical devices, orthopedic implants, and dental applications [1, 2]. In addition, PEEK is transparent in X-rays, which makes it ideal for radiolucent instruments and components. Taken together, PEEK materials have a variety of excellent properties that make them promising for use in a wide range of applications in the medical field. However, the mechanical strength and elastic modulus of polyetheretherketone materials are relatively low, and they can only be used in human bone with low elastic moduli and low strength requirements [3]. Therefore, it is necessary to further improve the biomechanical properties of PEEK to expand its application in load-bearing regions of the bone. The best way to achieve this is through filler modification, whereby adding fillers to PEEK can improve its mechanical properties (e.g., tensile, compressive, flexural strength, modulus, and toughness). Materials that are commonly used in filler-modified polyetheretherketone fillers include carbon fibers, metal oxides, carbon nanotubes, graphene oxide, and multi-component composites [4, 5, 6]. Carbon fiber (CF) exhibits excellent mechanical properties, chemical stability, a very light weight, high stiffness values, and high levels of temperature resistance, among other properties. When polyetheretherketone (PEEK) is combined with carbon fiber, the overall mechanical properties of the composites can be effectively enhanced [7]. Three main factors affect the mechanical properties of PEEK/CF: the proportion of CF that is added, the length of the CF, and the interfacial interaction between CF and polyetheretherketone [8]. [PERSON] et al. [9] successfully prepared a series of CF/PEEK composites with different carbon fiber contents. The test results showed that, at a carbon fiber content of 40%, the CF/PEEK flexural strength, flexural modulus compressive strength, and compressive modulus reached the optimum, which provided a basis for further research on CF/PEEK composites as orthopedic and implant materials. [PERSON] et al. [10] prepared continuous carbon-fiber-reinforced polyetheretherketone (CCF/PEEK). Short-cut carbon-fiber-reinforced polyetheretherketone (SCF/PEEK) and mechanical experiments led to the conclusion that CCF/PEEK is stronger than SCF/PEEK and pure PEEK in terms of tensile strength, bending strength, and flexural modulus, as well as being more suitable for applications in which higher strength is required. However, short-cut carbon fiber (SCF) is much cheaper than continuous CF, and PEEK/SCF composites can be easily fabricated using conventional extrusion and injection molding techniques; PEEK composites may offer a non-metallic alternative to titanium and a prospective material in bone tissue engineering. [PERSON] et al. [11] added polyethereketone (PEKK) to the surface of activated carbon fibers, and it was experimentally shown that the interlaminar shear strength, flexural strength, and modulus were increased by 70%, 37%, and 48%, respectively. [PERSON] et al. [12] grafted amine-based graphene oxide onto oxidized CF to prepare CF/PEEK implants. The dispersion of CF in the composites was significantly improved. The flexural strength, compressive strength, and hardness of CF/PEEK were increased by 51%, 46%, and 30%, respectively; CF/PEEK composites with the dual functions of mechanical reinforcement and osseointegration facilitation have excellent potential for orthopedic/dental applications. Metal-oxide-reinforced polyetheretherketone (PEEK) is a plastic commonly used in high-temperature and high-strength applications. Adding metal oxides can improve various properties of PEEK, such as enhancing its thermal conductivity and wear resistance. Some common metal oxides include aluminum oxide, titanium oxide, and zirconium oxide [13; 14].