Biodegradation Resistance and Bioactivity of Hydroxyapatite Enhanced Mg-Zn Composites via Selective Laser Melting.

Cijun Shuai,Yuanzhuo Zhou,Ping Wu,Pei Feng,Sheng Yang,Chongxian He,Mingchun Zhao,Youwen Yang,Long Liu,Chengde Gao

doi:10.3390/ma10030307

Abstract

Mg-Zn alloys have attracted great attention as implant biomaterials due to their biodegradability and biomechanical compatibility. However, their clinical application was limited due to the too rapid degradation. In the study, hydroxyapatite (HA) was incorporated into Mg-Zn alloy via selective laser melting. Results showed that the degradation rate slowed down due to the decrease of grain size and the formation of protective layer of bone-like apatite. Moreover, the grain size continually decreased with increasing HA content, which was attributed to the heterogeneous nucleation and increased number of nucleation particles in the process of solidification. At the same time, the amount of bone-like apatite increased because HA could provide favorable areas for apatite nucleation. Besides, HA also enhanced the hardness due to the fine grain strengthening and second phase strengthening. However, some pores occurred owing to the agglomerate of HA when its content was excessive, which decreased the biodegradation resistance. These results demonstrated that the Mg-Zn/HA composites were potential implant biomaterials.

Highlights

Over the past decade, Mg alloys have been known as potential bone implants owing to their biodegradability and suitable elastic modulus [1,2,3]
A relatively large dendrite grain was found in the Mg-3Zn alloy (Figure 1a)
The results showed that the HA particles contributed to the grain refinement of Mg-3Zn alloy, which was attributed to the heterogeneous nucleation in the process of solidification

Summary

Introduction

Mg alloys have been known as potential bone implants owing to their biodegradability and suitable elastic modulus [1,2,3]. The biomedical application of Mg-Zn alloys is hindered mainly caused by their too rapid degradation, leading to the loss of the mechanical stability before the formation of new bone [8,9]. Hydroxyapatite (HA, Ca10 (PO4 ) (OH)2 ) possesses a low solubility and can induce the formation of bone-like apatite layer in body environment, which makes it a potential reinforcement for increasing the biodegradation resistance of Mg alloys [10,11,12]. Sunil et al [13] found that nano hydroxyapatite could increase the corrosion resistance of Mg prepared by friction stir processing (FSP). Campo et al [14]

Results

Discussion

Conclusion