Microstructure study of porous biphasic calcium phosphate ceramics

Porous hydroxyapatite (HAP)/β-tricalcium phosphate (β-TCP) ceramic is similar to natural bone in many features and is widely used as implant materials as well as bone augment. 40% β-TCP and 60% HAP coprecipitated powders were synthesized by the wet chemical method, and porous biphasic calcium phosphate ceramics (BCPC) were fabricated. An aqueous solution of lactic acid (0.01M) was used to etch β-TCP from the HAP matrix. We used digital image processing and scanning electron microscopy (SEM) and X-ray diffraction (XRD) to study the microstructure of porous BCPC systematically. Based on SEM images, the digital image process was used to reconstruct the boundary of HAP/β-TCP grains and to provide quantitative information about microstructure parameters of BCPC, such as mean sizes and number distributions of micro- and macropores, mineral area fraction (MAF) as well as preferred orientation of macropores. The polar distribution map of macropores along the Z-axis was used to express the preferred orientation of macropores. The macro- and micropores distributed normally. The β-TCP agglomeration and distribution in irregular form in HAP matrix indicated that the coprecipitated powders of HAP/β-TCP were not homogeneously coprecipitated