Physicomechanical, Phase Composition, and In Vitro Study of High-Temperature Sintered ZTA/HA Composites
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RODUCTION
THE great need for biocompatible materials with high mechanical properties has induced scientists to look for new materials. Bioceramics are currently treated as one of the most biomaterials which possess promising applications in the biomedical technology field.[1,2] Implanted bioceramics possessed the advantage of being compatible with the human body environment. Their biocompatibility is arising from their chemical composition, which includes ions commonly found in the physiological environment (such as Ca2+, Mg2+, K+, Na+, etc…).[3] Due to the excellent bioactivity and biocompatibility of hydroxyapatite and tricalcium phosphate (b-TCP), they are widely applied as bone substitute materials. The essential drawback of such materials is their unfavorable low mechanical strength, which restricts their application as a load-bearing bone substitute. To make such bioactive ceramics suitable for loadbearing bone repair applications, introducing of reinforcing material is preferred. ZrO2, Al2O3, and zirconiatoughened alumina (ZTA) are excessively used to improve the mechanical properties of bioceramic materials due to their excellent mechanical properties.[4–10]
S.M. NAGA, M. SAYED, and H.F. El-MAGHRABY are with the National Research Centre, Ceramics Department, El-Bohous Str., Dokki, Cairo 12622, Egypt. Contact email: [email protected] Manuscript submitted January 7, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS A
The greatest disadvantage of ZrO2 is its bioinert behavior, which might lead to the formation of a fibrous tissue layer surrounding the implant. Such a formed fibrous layer encourages debonding between the implant and the living tissue.[11,12] To overcome the abovementioned problem, either ZTA was coated with a bioactive material[13–18] or a composite formulated from ZTA/ bioactive material was created.[19–25] To prepare the nanohydroxyapatite (HA)/ZTA composite, nano-HA prepared by the precipitation method was mixed with different weight percentages of zirconiatoughened alumina (ZTA) powder prepared via the solgel technique. ZrO2-Al2O3 powder was prepared by the colloidal procedure, which used the electrostatic force between the ZrO2 sol and the Al2O3 starting material. The results showed that the addition of 15 wt pct ZA to nano-HA notably improved the bending strength, while the addition of 30 wt pct ZA reduced both the bending strength and the fracture toughness of the produced composite. The decrease in the bending strength and fracture toughness was attributed to the formation of tricalcium phosphate (TCP) and porosity, which resulted from the increase in the contact area between ZrO2 and HA.[21] ZTA powder fabricated by combined precipitation and calcined at 1250 C was mixed with HA powder, fabricated via a wet chemical route, and either MgF2 or CaF2 as a source for fluorine to improve the sinterability of the prepared ZTA/HA composites. The results showed that with the increase in the HA content, the mechanical properties of the composite were enhanced.
The produced composites were bioa
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