Effect of grain size and density of spray-pyrolyzed hydroxyapatite particles on the sinterability of hydroxyapatite disk

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density

“…Nucleation and growth models of hydroxyapatite crystals based upon the degree of supersaturation in a calcium phosphate droplet, which depends upon the initial concentration of the precursor solution and the spray pyrolysis temperature, are believed to be appropriate for explaining the different size reduction and densification behaviors of hydroxyapatite particles during spray pyrolysis.…”

“…The sintering density of hydroxyapatite disks depended critically upon the size and density of their constituent particles, which in turn depended upon the precursor concentration and the spray pyrolysis temperature . The sintering density of hydroxyapatite disks increased as the precursor concentration was decreased, when the spray pyrolysis temperature was fixed; it was also increased by increasing the spray pyrolysis temperature, when the precursor concentration was fixed (Table ).…”

“…It can also be used as a continuous process, and thus is suitable for mass production. However, it is difficult to control the morphology and size distribution of powders produced by pyrolysis, which are known to depend critically upon processing conditions such as reaction temperature, carrier gas flow rate, the concentration of the precursor solution used, and the strength of the droplet generator. Additionally, it is difficult to achieve highly dense particles due to the evolution of gas by the decomposition of reactants during spray pyrolysis at high temperature …”

“…Hydroxyapatite is a bone grafting material that bonds to bone and not the intervening fibrous tissues. Thus, many processing methods have been developed to synthesize hydroxyapatite powder; spray pyrolysis is one of them, but has been rarely used so far due to its delicate processing methods . The biggest problem that must be solved to apply it as a tool for synthesizing hydroxyapatite powder is to achieve small and highly dense particles.…”

Reaction sintering of kaolin-natural phosphate mixtures

“…They have been considered as representative materials for bone grafts due to their similarities to the bone apatite [2]. HAp materials are also used for separation and purification of proteins and in drug delivery systems [3].…”