Modeling Relations between Processing, Microstructure and Mechanical Properties of Porous Bioceramics

Abstract

Biphasic calcium phosphate (BCP) bioceramics, for use as resorbable bone substitutes, containing both isolated macropores and interconnected micropores, have been fabricated by sintering, using naphtalen particles as a porogen to produce macropores. The resulting ceramics contain ~ 45% macropores and various amounts of microporosity. Mechanical properties (compression and bending strength, toughness and hardness) have been measured and modeled by combining two approaches, at two different scales: the one describes the mechanical properties of a partly sintered stacking of grains, supposed to account for the interconnected microporosity, the other one holds in the case of closed and isolated macropores within a continuous matrix. The material is then represented as a quasi-continuous matrix containing macropores, the matrix being itself microporous. The model also considers that fracture always initiates on a macropore, which allows to set a correspondence between fracture toughness and fracture stress equations. The mechanical tests performed on the sintered ceramics tend to validate the modeling approach.