Papers by Author: Qing Xia Zhu

Abstract: In-vitro experiment method was used to study biomineralization properties of carbonate apatite bulk and electrophoresis coating with different carbonate contents. The mineralization processes in SBF solution were investigated by means of XRD, SEM and so on. Research results show that the apatite with poor crystallization and small grain size induced by the carbonate substitution is beneficial to the sintering of the bulk and the formation of the bone-like hydroxyl-carbonate apatite (HCA) layer on the surface after soaking in the SBF. However, the carbonate substitution greatly reduces the pore size and porosity of coating, which is not conducive to the deposition and growth of the mineralized layer, thus weakens the biomineralization properties of the coating.

Abstract: Aluminum titanate (Al₂TiO₅) powder has been synthesized at low temperature via nonhydrolytic sol-gel method by using aluminum powder as aluminum source, titanium tetrachloride as titanium source, anhydrous ethanol as oxygen donor with different catalysts. The phase transformation of aluminum titanate xerogel powder during heat treatment and the influence of the mixing orders of raw materials, catalyst kinds on the synthesis of aluminum titanate were investigated by means of differential-thermal analysis (DTA-TG), X-ray diffraction (XRD), transmission electron microscope (TEM). The results indicated that aluminum titanate powder was easily synthesized at 750 °C by using AlCl₃ as catalyst with a mixing order of adding TiCl₄ before AlCl₃ into aluminum alcohol mixture. The catalytic order of the different catalysts in the preparation process of aluminum titanate is: FeCl₃> AlCl₃> MgCl₂. The catalyst promoted the activation of metal aluminum powder and played a major role in the synthesis of aluminum titanate powder at low temperature via nonhydrolytic sol-gel method.

Abstract: ron-zircon pigment has been synthesized by non-hydrolytic sol-gel method using zirconium chloride and tetraethoxysilane as precursors, anhydrous ferric chloride as colorant, lithium fluoride as mineralizer and anhydrous ethanol as solvent. Iron-zircon pigment has been characterized by means of DTA-TG, XRD, Colorimeter and TEM. The results show that only a small fraction of iron is incorporated in the zircon crystal structure while the remaining iron cations are trapped within the zircon matrix. The iron-zircon with the red value (a*) of 20.64 can be synthesized at 700°C with the optimum Fe/Zr molar ratio of 0.2.

Abstract: The nanosized fluorhydroxyapatite (FHA) had been synthesized by aqueous precipitation method. The effects of synthesis temperature,fluoride ion concentration and pH value on the fluoride substitution were investigated.The phase composition and the change of crystal structure were characterized by X-ray diffraction and fourier transform infrared spectroscopy. The results show that crystal lattice parameters and bond energy make changes by incorporation of F in the structure.The size of FHA crystals increase as the precipitation temperature. The phase composition of FHA is mainly controlled by the pH value.

Abstract: Carbonated hydroxyapatite (CHA) was synthesized by solid-ion-exchange reaction of hydroxyapatite (HA) powders in CO2 atmosphere. The effects of the treatment atmosphere, temperature and time on carbonate substitution were investigated. The phase composition of the powders were characterized by X-ray diffraction and the content and type of the carbonate substitution were studied using Carbon-sulfur elemental analysis and Fourier transform infrared spectroscopy, respectively. The results show that the carbonate ion can enter the HA crystal lattice to form CHA giving priority to A-type by controlling the treatment temperature, atmosphere and time. Wet atmosphere treatment favors the reconstitution of hydroxyl and treatment in dry CO2 atmosphere favors the formation of A-Type substitution. The appropriate reaction temperature is 900 . Carbonate content increases with the treatment time and a further extension of treatment time tends to a slower increase of carbonate content.

Abstract: Carbonated hydroxyapatite (CHA) and hydroxyapatite (HA) were prepared by the wet chemical method. The contact angle was measured to calculate the surface energy. The biomineralization process in SBF solution of HA and CHA were investigated in vitro. The cell attachment and proliferation behavior of CHA and HA were compared by the cell culture experiments. The results show that the polar component of surface energy of B-type CHA is higher than that of HA. Osteoblastic cells attach and proliferate very well on the surface, which indicates the excellent cell compatibility. The CHA have high bioactivity owing to rapid formation of hydroxyl-carbonate-apatite (HCA) mineralized layer on the biomaterial’s surface in SBF.

Abstract: Stability of hydroxyapatite(HA) structure is influenced by preparation conditions and afterwards heat treatment. In this paper, the powders with different Ca/P molar ratio were calcined to investigate the influence of Ca/P and heat treatment on thermal decomposition and reconstitution of HA. The results show that the Ca/P has little change even calcined at a high temperature of 1500°C. The Ca/P molar ratio close to 1.67 is beneficial to form high purity HA. HA gradually releases its OH- ions in the temperature range of 800-1200°C. The decomposition takes place at about 1200°C and will become more and more severe with the increase of temperature. Cooling with slow rate and post-heat treatment in wet atmosphere are beneficial to both the rehydration and the recovery of HA from the decomposition products (TTCP and α-TCP).