Structural design and experimental analysis of a selective laser sintering system with nano-hydroxyapatite powder

Hydroxyapatite (HA) is a ceramic transposition material which has been widely used for artificial bone. However, its applications are limited to a small implantation for non-bearing bone repair due to its high brittleness, low strength and poor mechanical properties. Thus, nanotechnology has been employed to improve the mechanical properties (torsion modulus, tensile strength and fatigue resistance, etc.) of HA for bone implantation. In this study, we developed a selective laser sintering system for fabrication of artificial bone with nano-HA powder. The key characteristics of this novel system is the laser with fast heating and fast cooling properties, which efficiently prevents the nanosize particles from forming micron size ones in the process of the sintering. The microstructure of the sintered nano-HA scaffolds produced in this system was investigated under Scanning Electron Microscopy (SEM). We showed that the size of nano particles were increased with the prolonged sintering time. Moreover, they are more in shape of granules instead of the original shape of needle. We suggest that the nano HA scaffolds which meet the requirements for the mechanical and biological properties of bone can be obtained by optimizing the sintering time.