Microstructure, corrosion degradation, and tribocorrosion behavior of biodegradable porous Zn-Cu scaffolds

Porous Zn scaffolds are considered promising next-generation biodegradable antibacterial bone implants. This work provides insight into the influence of Cu content and porous structure on the evolution of corrosion degradation and tribocorrosion mechanisms of porous Zn-Cu scaffolds, offering guidance for the design and application of porous materials in bone tissue engineering. Porous Zn-Cu scaffolds with 0, 1, 2, and 3 wt% Cu and a 60 % porosity were effectively fabricated using the space-holder technique. The microstructure, microhardness , corrosion degradation, and tribocorrosion behavior were systematically studied. The results show that porous Zn-Cu scaffolds, with an average pore diameter of 311.57 ± 125.69 μm, consist of η-Zn, ZnO, and ε-CuZn₅ phases. The CuZn₅ phase significantly increases the microhardness of porous Zn-Cu while reducing both corrosion and degradation rates. The corrosion degradation progresses through three stages, with the corrosion modes exhibiting both uniform corrosion and pitting . Notably, the degradation rates of porous Zn-(0, 1, and 2 wt%) Cu were consistent with the requirements for bone implants. Tribocorrosion testing revealed that the porous structure can effectively suppress the fluctuation of OCP. However, increasing Cu content promotes the removal of passive film. Wear mechanisms include a mixture of abrasive and adhesive wear , with higher Cu content intensifying corrosion and promoting wear. Four typical wear modes were identified in the T cell , while in the T strut , increasing Cu content led to the formation of prominent cracks and micropits.