Y2O3 and CaO zirconia as reinforcement for hydroxyapatite biocomposite

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Date
2016-09-01
Authors
Zaw Linn Htun
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Zirconia reinforced hydroxyapatite (ZrO2/HAp) biocomposites were fabricated to improve the strength and fracture toughness of monolithic HAp. Commercial Y2O3- ZrO2 and CaO-ZrO2 were selected as the reinforcement for the HAp matrix. The ZrO2/HAp samples were produced by conventional ceramic processing route. The samples were initially produced by pure mixing as well as milling-mixing system. Better physical and mechanical properties were observed from milling-mixing. 5 wt% of commercial Y2O3-ZrO2 was used to reinforce HAp and various amount of CaF2 (1, 3, 5, 7 and 9 wt%) were added to the ZrO2/HAp biocomposite as sintering aid. Samples were compacted with a uniaxial pressure of 90 MPa. The samples were then sintered from 1050°C to 1250°C for 5 hours. The optimum flexural strength of 61.10 MPa and fracture toughness of 1.15 MPa.m1/2 was achieved by 3 wt% of CaF2 addition. From this study, 3 and 5 wt% of CaF2 were selected as optimum addition. Subsequently, 5 and 10 wt% of CaO-ZrO2 were incorporated to HAp to improve the strength and toughness of the HAp as compared with Y2O3-ZrO2 addition. The selected amounts of CaF2 were also added to CaO-ZrO2/HAp biocomposites. The mechanical properties of CaO-ZrO2/HAp biocomposite were found to be better than the optimum properties of monolithic HAp. The biocomposite achieved better flexural strength of 54.77 MPa with higher density 3.14 gcm-3 and fracture toughness of 1.33 MPa.m1/2. The bioactivity test on both Y2O3 and CaO-ZrO2 reinforced HAp biocomposites revealed the formation of apatite layer on the surfaces, indicating the biocompatibility and potential bone forming ability.
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