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Information × Registration Number 0302U005144, 0100U003281 , R & D reports Title Physics, technology and diagnostics of hydroxyapatite-based nanodisperse biomaterials popup.stage_title Одержання біоматеріалів з нанодисперсного порошку та їх діагностики Head Zyman Z.Z., Registration Date 25-03-2002 Organization Kharkov National University named after V.N.Karazin popup.description2 The object of research are the biomaterials based on nanodispersive HA powder and their diagnostic. The aim of the work is physical processes study which are take place at the dense and porous ceramics production based on nanodispersive HA powder. The methods of research are {-ray analysis, IR spectroscopy, optical and electron microscopy, dilatometry. It has been shown that one of the methods of hydroxyapatite sintering temperature reduction connectes with the use of a powder, which has the particles consisting of crystalline and amorphous-like constituents. Shrinkage of the pressings which were made from this powder starts at middle temperatures (600-700 oC) and realizes according to particles mutual sliding mechanism. With the increasing of the pressings firing temperature, this stage transfers to another one, which is realized by a diffusion mechanism (over 900 oC). A shrinkage curve on the sliding stage has a stepped character. It is caused by a stopping effect of the gas pressure on the shrinkage, which exudes as a result of crystallization of the amorphous-like constituent, and partly accumulates in closed cavities and pores. The contribution of the two mechanisms to the shrinkage process is determined by the crystallinity degree of the powder (i.e. the ratio between the crystalline and the amorphous-like constituents). If a powder has a higher crystallinity degree, the first stage transfers to higher temperatures area and the stepped character of the shrinkage curve becames smoother. The sliding stage for pressings of crystalline powder is practically lacking, and a noticeable shrinkage starts at high temperatures (over 900 oC) when diffusive processes develop. In accordence with the dense ceramics sintering data the producing method of porous HA granules with 4-6 mm in diameter and the fixed macro- and microporosity has been developed. Spherical macropores with 350-600 mkm in diameter can occupy up to 50% of granule volume and micropores, which are the complex of interconnected channels, can occupy up to 25-35% of granule volume. The structure of porosity is similar to that one of the human bone mineral carcass and this similarity has to improve the healing of bone defects at the surgical osteoplastics uses. Product Description popup.authors popup.nrat_date 2020-04-02 Close