Effect of lanthanum oxide additive on the sinterability, physical/mechanical and bioactivity properties of hydroxyapatite-alpha alumina composite

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Pazarlıoğlu S. S. , Salman S.

Journal of the Australian Ceramic Society, vol.1, no.1, pp.1-14, 2019 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 1 Issue: 1
  • Publication Date: 2019
  • Doi Number: 10.1007/s41779-019-00336-4
  • Title of Journal : Journal of the Australian Ceramic Society
  • Page Numbers: pp.1-14


The aimof this study was to evaluate the effect of lanthanumoxide (La2O3) additive on the microstructural, physical, mechanical,

and in vitro bioactivity properties of hydroxyapatite (HA)-alpha alumina (α-Al2O3) composite. The monolithic HA as well as

composites of HA-5 wt% α-Al2O3 and HA-5 wt% Al2O3-(0.5 wt%, 1.5 wt%, and 2.5 wt%) La2O3 were uniaxially pelleted at

350 MPa with a size of ∅11 and 11 mm2 and sintered at the temperatures ranging from 1100 to 1300 °C for 4 h. The highest

mechanical strength values of 130.20 ± 6.22 MPa, 60.27 ± 9.93 MPa, and 0.96 ± 0.05 MPa m1/2 for compressive strength

(σcompressive), three-point bending strength (σthree-point bending), and fracture toughness (Kıc) were obtained for monolithic HA,

respectively. While the decomposition (transformation of HA to secondary phases such as beta-tricalcium phosphate (β-TCP),

alpha-tricalcium phosphate (α-TCP), and calcium oxide (CaO)) ratio was about 5.7% for monolithic HA, it attained to 27.4% for

HA-5wt% α-Al2O3 composite. However, addition of La2O3 to HA-5 wt% α-Al2O3 composite contributed to decreasing of

decomposition from 27.4 to 22.0%. The mechanical strength values of σcompressive of 214 ± 32.50 MPa, σthree-point bending of 75.70

± 2.40MPa, and Kıc of 1.95 ± 0.10 MPa m1/2 were obtained for HA-5wt% α-Al2O3 composite. SEM images exhibited that α-

Al2O3 led to decreasing the in vitro bioactivity ofHA. However, La2O3 additive contributed to improvement of the mechanical as

well as bioactivity properties of HA-5 wt% α-Al2O3 composite. HA-5 wt% α-Al2O3-0.5 wt% La2O3 composite can be used as a

bioceramic in human body, because it has enough mechanical properties as well as its desirable in vitro bioactivity.