Pre-oxidation induced in situ interface strengthening in biodegradable Zn/nano-SiC composites prepared by selective laser melting
Chengde Gao, Yao Meng, Shuping Peng, Wei Tan, Cijun Shuai
Abstract
Nano-SiC has attracted great attention as ceramic reinforcement in metal matrix composites, but the weak interface bonding between them remains a bottleneck for efficient strengthening. In this study, pre-oxidation treatments and selective laser melting (SLM) were employed to prepare Zn/nano-SiC biocomposites with strengthened interface bonding via in situ reaction. Nano-SiC and Zn powders were pre-oxidized respectively, and then used to prepare Zn/nano-SiC biocomposites via SLM. The powder microstructure, and the interface characteristics and mechanical properties of the biocomposites were investigated. The degradation properties and cell response were analyzed to evaluate their feasibility for orthopedic applications. The results indicated that the pre-oxidation treatments generated a uniform oxide layer on the surface of both nano-SiC and Zn particles and the thickness of the oxide layer increased with pre-oxidation temperature. During the SLM process, the oxide layers not only improved the metal-ceramic wettability by reducing interface energy, but also induced in situ reaction to form chemical bonding between the Zn matrix and nano-SiC, thereby improving the interface bonding. Consequently, the Zn biocomposite reinforced by nano-SiC with a pre-oxidation temperature of 1000 °C (ZS1000 biocomposite) exhibited more transgranular fracture and significantly enhanced compressive yield strength of 171.5 MPa, which was 31.6% higher than that of the Zn biocomposite reinforced by nano-SiC without pre-oxidation. Moreover, the ZS1000 biocomposite presented slightly accelerated degradation which might be ascribed to the facilitated electron transfer by the interface product (Zn2SiO4). In addition, the ZS1000 biocomposite also showed appropriate biocompatibility for MG-63 cell adhesion, growth, and proliferation. This study shows the potential practical applicability for the preparation of Zn-based biocomposites with strong interface bonding and mechanical properties for orthopedic applications.