ADDITIVE MANUFACTURING FOR BONE LOAD BEARING APPLICATIONS - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 247

FIGURE 11.9
Fabrication process of 3D printed structures by powder-bed AM, (a) feeding bed and building bed are indicated,
(b) the compartment moves forward to inject the binder on the building bed, one layer of binder is injected on the
powder bed, compartment moves backward to spread another layer of powder onto the building bed.
FIGURE 11.10
SEM images of HG4 nanocomposite, (a) graphene-coated Hap particles; (b) showing higher magnifications. The
nanoparticles seen in (b) could be attributed to agglomerated graphene oxide sheets.
to fabricate HA/graphene nanocomposite. SEM images of the nanocomposite powder show that HA
flakes are fully decorated by graphene particles (see Figure 11.10 ). This texture can lower the van der
Waals attractive forces between the particles. It was shown that the flowability of the nanocomposite
powder, which is an essence in the manufacturing process, was improved significantly by the addition of
graphene. The samples printed at the layer thickness of 125 m m with the shell binder saturation (SBS) to
core binder saturation level (CBS) of 100/400% showed the highest mechanical strength. As seen in Fig-
ure 11.11 , the compressive strength of the 3D-printed cylinders was increased from ∼ 0.1 to ∼ 7.0 MPa
in the samples with the graphene content of only 0.4 wt%.
In summary, it was realized that the flowability of HA particles decorated with graphene was im-
proved significantly. This phenomenon will enhance the resolution and quality of the structures 3D-
printed through AM. It was also shown that the mechanical strength of HG4 green specimens was almost
70 times more than HG0 specimens. In future efforts to employ the samples for bioimplantation, the
mechanical properties and biocompatibility of the sintered samples should be investigated thoroughly.