Physico-mechanical and morphological features of zirconia substituted hydroxyapatite nano crystals

S F Mansour,S I El-Dek,M K Ahmed

doi:10.1038/srep43202

S F Mansour, S I El-Dek + Show 1 more

Open Access

https://doi.org/10.1038/srep43202

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Abstract

Zirconia doped Hydroxyapatite (HAP) nanocrystals [Ca10(PO4)6−x(ZrO2)x(OH)2]; (0 ≤ x ≤ 1 step 0.2) were synthesized using simple low cost facile method. The crystalline phases were examined by X-ray diffraction (XRD). The crystallinity percentage decreased with increasing zirconia content for the as-synthesized samples. The existence of zirconia as secondary phase on the grain boundaries; as observed from scanning electron micrographs (FESEM); resulted in negative values of microstrain. The crystallite size was computed and the results showed that it increased with increasing annealing temperature. Thermo-gravimetric analysis (TGA) assured the thermal stability of the nano crystals over the temperature from room up to 1200 °C depending on the zirconia content. The corrosion rate was found to decrease around 25 times with increasing zirconia content from x = 0.0 to 1.0. Microhardness displayed both compositional and temperature dependence. For the sample (x = 0.6), annealed at 1200 °C, the former increased up to 1.2 times its original value (x = 0.0).

Highlights

Kmita et al They reported that the transformation of ZrO2 from monoclinic to tetragonal phase was responsible for the reinforcing mechanism[16]
Miecznik et al have studied the addition of zirconia on HAP hot pressed materials and the results presented extraordinary enhancement of hardness and mechanical strength compared to pure HAP27
The influence of zirconia incorporation in HAP matrix on (PO4)3− crystallographic site have been scarcely reported. In this piece of work, we aimed to investigate the effect of zirconia doping content on HAP microstructure and explore the physical properties of the obtained nanocrystals

Summary

Introduction

One of the most common applications is the use of HAP as a coating layer on zirconia (ZrO2) nano particles This resulted in higher bonding strength, improved mechanical properties, biocompatibility and high corrosion resistance[22]. Silva et al synthesized composite of partially stabilized zirconia/HAP They discussed the hypothetical incorporation of Ca2+ by Zr4+ in the HAP structure. Matsumotoa et al, studied HAP/zirconia composite with microporous structure and they found that the later exhibited high protein adsorption and encouraged cellular affinity. They argued that the investigated composite possesses excellent strength which is equivalent to that of cortical bones[26]

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