Effects of the addition of boron nitride nanoplate on the fracture toughness, flexural strength, and Weibull Distribution of hydroxyapatite composites prepared by spark plasma sintering.

Hydroxyapatite (HA) has inherently low fracture toughness and low flexural strength, thus limiting it from wide scale application as an implant material in the biomedical field. To increase the fracture toughness and flexural strength, HA composites were fabricated by adding boron nitride nanoplatelets (BNNP) as reinforcement. Spark plasma sintering was utilized to achieve fine grain structure. The addition of BNNP facilitated grain size refinement. The BNNP reinforced HA composites exhibited increased fracture toughness (2.3 MPa m) and flexural strength (79.79 MPa) of HA over previous published values (1.0 MPa m). Despite that the Weibull Distribution indicated a sacrifice in mechanical reliability, all the composites fabricated in this study showed a low probability of failure and a factor of safety (~ 5.6) that is consistent with that of human bones (~ 6). In addition, the current study provides an approach to statistically design sintering parameters and mechanical loading for fabrication of ceramics.