Effect of Sintering Temperature on Some Physical And Mechanical Properties of Fabricated Hydroxyapatite Used For Hard Tissue Healing

This work focuses on studying the role of drying and calcination on stiochiometry and crystallinity of deposited HA. Also, studying the effect of sintering temperature on phases generated, physical and mechanical properties of sintered HA powder compact at a range of (800-1200) ̊ C. Both Ca/P ratio and crystallinity were increased after calcination, where the Ca/P ratio raised from 1.7 to 1.9 and the height of Hydroxyapatite peak intensity was also increased .Secondary phases also appeared. X-ray diffraction patterns and electrical microscopic pictures of polished surfaces of the Hydroxyapatite compact after sintering had revealed the process of densification and crystallization of Hydroxyapatite . The increase of sintering temperature leads to grain growth, while surface cracking and other defects became lower i.e. porosity and surface voids. Both hardness and fracture strength were increased for samples sintered at high temperatures where they reached their maximum values at sintering temperature (1200)oC .The maximum linear shrinkage was 20% at sintering temperature 1200oC. The maximum bulk density was (2.173) g/cm at sintering temperature of 1200oC and the maximum apparent density was (2.58) g/cm at sintering temperature 900oC. The maximum apparent and open porosities were 47.136% and 47.058% respectively at sintering temperature 900oC. The maximum water absorption was 39.13% at sintering temperature 800oC.