Investigating the mechanical behavior of hydroxyapatite-reduced graphene oxide nanocomposite under different loading rates

Abstract

In this study, the hydroxyapatite (HA)-reduced graphene oxide (rGO) nanocomposite was investigated for its mechanical properties. The nanocomposite used in this study was made in two stages. The HA-rGO powders were first synthesized by hydrogen gas injected hydrothermal method, and then consolidated by spark plasma sintering. HA-rGO nanocomposite was subjected to Vickers indentation experiments with different loading rates. Various analyzes have been used in this study, including x-rays diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, fast fourier transform, and inverse fast fourier transform. The findings of this study showed that the HA in this nanocomposite was reinforced with rGO sheets coated with HA. As the loading rate increased, the slope of the curves in the elastic region was increased, indicating that the elastic modulus was increased. Also, the contact depth at higher loading rates was increased. Plastic deformation was higher at higher loading rates and the hardness had increased. As the loading rate increased from 300 mN to 1 N, the hardness and elastic modulus increased with more slope than when the loading rate changed from 1 N to 2 N. The presence of rGO sheets had partially controlled the HA brittleness.

Characterization of hydroxyapatite-reduced graphene oxide nanocomposites consolidated via high frequency induction heat sintering method

“…This increase was higher than in previous reports. For example, in a report with similar conditions [10], an elastic modulus of 115 GPa was reported, which is lower than the values reported in this study (146.3 GPa) and a hardness of 5 GPa was reported, which is lower than the values reported in this study (7.39 GPa). This was due to the increase in mechanical properties because of the use of solvents, the injection of nitrogen gas (gas injection increases the reduction rate of GO and increases the crystallinity of HA.…”

“…But despite the extraordinary properties mentioned, the poor mechanical behavior of HA has limited its practical scope. High brittleness, low fracture toughness, and poor wear resistance are among the mechanical characteristics of HA that are very effective in implant applications and need to improve [10][11][12].…”

Comparison of the effect of argon, hydrogen, and nitrogen gases on the reduced graphene oxide-hydroxyapatite nanocomposites characteristics

“…Reduced graphene oxide has an amorphous structure and its broad peak is covered with (002) planes of HA at 2theta≈26. In a previous report, pure GO was exposed to similar hydrothermal conditions, and the results of XPS confirmed that it was well reduced [24]. The TEM image of the HA particles shows that the morphology of these particles is nanorods with diameters of about 40 nm and longitudinally variable.…”

“…HA (Ca 10 (PO 4 ) 6 (OH) 2 ) has unique biomaterial properties such as resemblance to bone mineral, biocompatibility, bioactivity, osteoconductivity, non-immunogenicity, and non-toxicity. But still, it has poor mechanical properties such as intrinsic brittleness, low fracture toughness (fracture toughness of 0.28-1.08 MPa.m 0.5 ), poor tensile strength, and weak wear resistance which have limited the scope of its applications [22][23][24][25][26][27][28][29][30][31]. Researchers have tried various ways to overcome this weakness, including reducing particle size using nanotechnology techniques and adding reinforcing materials.…”

Improved Mechanical Properties of Ultra-High Shear Force Mixed Reduced Graphene Oxide/Hydroxyapatite Nanocomposite Produced Using Spark Plasma Sintering

“…A load test force of 0.5 Newtons was employed to measure the Vickers hardness of the sintered specimens. A previous study showed that the Vickers hardness increases with an increasing load [ 45 ]. At low loading rates, the energy is spent on plastic and elastic deformation.…”