Effect Of The Granulation Of Starting Powder On Superplastic Deformation Of Hydroxyapatite

¹Department of Materials and Life Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 1028554, Japan

²Advanced Key Technologies Division, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan

Adv. Mater. Lett., 2016, 7 (2), pp 130-135

DOI: 10.5185/amlett.2016.6135

Publication Date (Web): Jan 04, 2016

Copyright © IAAM-VBRI Press

E-mail: itatani@sophia.ac.jp

Abstract

The effect of the granulation of starting powder on the superplasticity of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) specimen was examined; the tensile elongation of specimen at high temperature was measured in order to evaluate the superplastic deformation. The translucent ceramics were fabricated using HAp powders with and without granulate (HAp and g-HAp) through the pulse current pressure sintering at 1000 ºC for 10 min: the mean grain sizes in both cases were approximately 0.2 mm. The tensile elongation of g-HAp specimen at 1000 ºC was 289 % (strain rate: 1.2 × 10^-3 s^-1). The tensile stress was always lower than 30 MPa with maximum stress of 28.3 MPa, in contrast to the case of HAp specimen showing the maximum stress of 75.3 MPa (tensile elongation: 344 %). The lower stress of g-HAp specimen, compared to the case of HAp specimen, indicated the weak bonding of grains, but the failure being occurred by the concentrated stress at the strong bonding sites.  

Keywords

Hydroxyapatite, superplasticity, pulse current pressure sintering.