Colloidal processing and sintering of hydroxyapatite

This paper describes the preparation of hydroxyapatite ceramics through slip casting and pressureless sintering. Based on the surface properties of HAp powder, a combination of two components, polyacrylic acid sodium salt (PAA-Na) and l-glutamic acid (GA), was used as the dispersing agents. HAp slurries with the solid content as high as 63 vol% could be prepared in the presence of the dispersants. After slip casting, green samples exhibited homogeneous microstructure. The samples were further densified at different temperature and soaking time. The microstructure, dehydroxylation behavior and mechanical properties were evaluated. In consideration of dehydroxylation, grain growth and blowhole development, it was found that 1250 °C with 2 h soaking is appropriate for sintering of HAp. Results showed that it was feasible to introduce l-glutamic acid as the second dispersant for improving the slurry stability and making more reliable HAp samples.