Fabrication and Evaluation of Porous Hydroxyapatite by Pressureless Sintering and Capsule-Free HIP Sintering

Development of porous hydroxyapatite is important for organic/inorganic composite biomaterials. In developing new biomaterials, it is fundamental to design and control the porosity characteristics. This study attempted to control the pore characteristics of porous hydroxyapatite using different sintering processes and temperatures. Porous hydroxyapatite was fabricated by the pressureless-sintering method and the capsule-free hot isostatic press (HIP) sintering method using two kinds of starting hydroxyapatite powder, spherical, and whisker-like powder. The pore size distribution in porous hydroxyapatite prepared from starting spherical and whisker powders depended on the sintering temperature. The higher the sintering temperature, the larger the pore diameter. The pore diameter in hydroxyapatite prepared by capsule-free HIPing was larger than that by pressureless-sintering. According to this understanding, various porous hydroxyapatites could be designed and their porosity characteristics controlled.