Boshytska N. Scientific principles of creation of ferromagnetic, oxide and nitride powders with controlled level of physicochemical and biological properties for medical application

The dissertation is devoted to the development of conception for creation of ferromagnetic, oxide and nitride powders with controlled level of physicochemical and biological properties aimed at solving the scientific-engineering problem of production of objects for medical application through establishment of their stability in the biological media of living organism. Physicochemical stability of powders of different chemical nature in inorganic and biological media of living organism has been investigated. Principal regularities and possible mechanisms of interaction of powders of various types with inorganic and biological media of wide spectrum of chemical compositions have been established through determination of changes in their particle size, specific surface area, phase composition, particle morphology particles in the media under study. The mechanisms of interphase interaction in ZrO2, SiO2, Al2O3 and TiO2 samples were investigated on the basis of the kinetics of their wetting in systems containing inorganic and biological media, thanks to which the possibility of using them as dispersion-strengthening additives to hydroxyapatite-based implant materials in order to improve physicomechanical characteristics has been shown. Stability of Si3N4 and AlN powders of various dispersity in human blood plasma was studied, and perspectiveness of using them as components of composite materials in dentistry was shown. Also, the intensity of wetting hydroxyapatite samples was established to depend on the porosity of solid phase and the optimal porosity of hydroxyapatite basic component in orthopedic implants was determined to be ~8 %. The mechanisms of titanium implant oxidation was studied in terms of the implant interaction with the mouth media. A corrosion-resistant (in physiological solution) and biocompatible composite coating on the medical titanium-aluminum-vanadium Ті-6АL-4V (VТ-6) alloy has been produced using deposition of an electric-spark TiAl3 coating followed by laser melting of slip hydroxyapatite plaster. Nanosized Fe3O4 powder with a specific surface area of 34,2 m2/g has been obtained by method of decomposition/reduction of iron oxalates. Nanosized ferromagnetic ?-Fe powder with a specific surface area of 31,4 m2/g and high stability in human blood plasma has been obtained by method of low temperature (250-400 °С) decomposition/reduction of citric acid salts in a hydrogen atmosphere and recommended as a magnetic component of bioresorbable composite materials. Carbon nanotubes have been manufactured on an iron catalyst, and dissolution of the iron on their surfaces in biological media has been studied, which made it possible to recommend them as magnetic sorbents of therapeutic compounds during short-term work in the organism. It was also established that stability of iron powders clad with nickel-phosphorus under various production conditions is higher than that of commercial powders. They are therefore recommended as a base of materials for medical instruments made by powder metallurgy methods instead of rolled steel. Hence, the important scientific-engineering problem that consists in developing and experimentally testing the conception of creation of powdered materials for medical application with physicochemical and biological properties required to provide their successful functioning in the living organism has been solved through complex investigation into stability of powders of different chemical nature in wide spectrum of inorganic and biological media. Keywords: nanopowder, biomedia, ferromagnetic powder, nitride, oxide, hydroxyapatite, blood serum, magnetic characteristics.