Advanced Materials Research Vols. 1030-1032

Abstract: The mechanism of the increased crystallization stability (the difference between glass incipient crystallization temperature and transition temperature) of Sb₂O₃ —doped vanadium phosphate sealing glass investigated by X-ray photoelectron spectroscopy (XPS) is reported in the present study. Experimental results showed that after doping with Sb₂O₃, the rate of bridging oxygen increased while the rate of no-bridging oxygen decreased, and the ratio of V⁴⁺/V_total also increased, too. This two changes led to the break of V=0 bond which is essential for the formation of V₂O₅ crystalline phase, thus inhibited the formation of that crystalline phase and improved glass crystallization stability.

Abstract: A double sealing coating was prepared on ultrasonic micro-arc oxidized pure magnesium substrate by adding nano-SiO2 particles as additive in the plating solution and coating SiO2 sol as sealing agent. The bonding characters of SiO2 sol was analyzed by Fourier transformed infrared spectrometry (FTIR). The compositions and morphology of seal coating were characterized by energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM), respectively. The corrosion resistance of the micro-arc oxidized and the sealed pure magnesium substrate were studied. The results showed that the Si content increased gradually with the addition of nano-SiO2 particles and the SiO2 sol sealing. It was benefit to create bioactive MgSiO3, which promoted the bone growth. The double sealed pure magnesium had a self-corrosion potential shifted positively by 60mV as well as a self-corrosion current density decreased by a half in a 3.5wt% NaCl solution, showing good corrosion resistance.

Abstract: pyrotechnic mixtures are sensitivity with the influence of humidity and are susceptible to explosive decompositions. The aim of this paper is to provide thermal decomposition data under different humidity conditions. The method of TG-DSC simultaneous analysis has been used to study the thermal decomposition mechanism of a typical red pyrotechnic mixture. The kinetic parameters were calculated by kissinger method. The thermal stability is evaluated by decomposition peak temperature (T_m), mass loss (△m) and activation energy (E), which shows that the decomposition peak temperature and activation energy decreased obviously. Therefore, the thermal safety under humidity atmosphere become lower.

Abstract: Li₂O-Al₂O₃-SiO₂ glass-ceramics doped with Nd₂O₃ were prepared by the melting method. The effects of Nd₂O₃ on the crystallization behavior of Li₂O-Al₂O₃-SiO₂ glass-ceramics were studied by DTA, XRD and SEM. With the increase of Nd₂O₃ content, the glass crystallization temperature arised. The SEM result indicates that the main crystal phase of Li₂O-Al₂O₃-SiO₂ glass-ceramics doped with Nd₂O₃ is β-quartz solid solution, for without doping Nd₂O₃ it is β-spodumene solid solution. These results shows that the crystallization temperature increases significantly by doping Nd₂O₃, and phase transition from β-quartz to β-spodumene is suppressed. The grain size increases with the increase of Nd₂O₃ content.

Abstract: Hydrolysis is one of the crucial steps in the product of titanium white pigment via sulfate process, and determines quality of the final products. Feed Speed have important effect to the quality and the numbers of seeds of early hydrolyzing. Using low concentration TiOSO₄ as raw materials, fine rutile white titanium pigment was prepared by optimizing the key parameters of the hydrolysis process via the achromatic force and the level of whiteness of the samples. The samples were characterized by SEM, particle size distribution and pigment properties test. Resultes have shown that the feeding speed of 1 min is 1.1times to the speed after 1 min. In this conditions, the obtained titanium white pigment showed better pigment performance.

Abstract: Using unconcentrated industrial TiOSO₄ solution as raw material, rutile TiO₂ white pigment was prepared via the self-seeded thermal hydrolysis sulfate process. The effects of pre-adding water volume ratio on the hydrolysis process and pigment properties of the TiO₂ white pigments were investigated. The samples were characterized by XRD, particle size distribution and pigment properties test. The pre-adding water volume ratio had great effects on the quantity and active of seed crystal, hydrolysis process, eventually determined particle size distribution and its pigment properties. The optimized pre-adding water volume ratio was of 0.22. The as-prepared rutile white pigment was with appropriate particle size, narrow particle size distribution and good pigment properties.

Abstract: Relative percentage content of Fe in tailings decreased from 15.92% to 10.71% after treated by using sulfuric acid mixed with oxalic acid at 350K for 60 min. And the relative content of Si decreased from 16.3% to 11.9% after treated by molten sodium hydroxide at 1073K for 30 min. Titanium content increased from 6.315% (original tailings) to 8.512% after removed Fe, and continued to go up to 10.44% after removed Si. The contents of Ca, P and Mn were slightly changed in entire enrichment process by XRF analysis. The phase change of the entire process was studied by XRD, and results indicated that tailings had very complex phases, and after removed Si the phase of tailings partly changed into FeTiO₃.

Abstract: In order to solve the problems of feasibility and conditions for synthetic reaction of SiO₂ in sputtering target of CoCrPt-SiO₂.The Co₃O₄ powder and Si powder were used in synthetic reaction experiments. It was found for experimental results that reaction product including SiO₂, Co₂SiO₄, Co₂Si and CoSi₂ at 1100°C, and keep the same with thermodynamics result. The reaction products under different temperature were listed in detail by thermodynamic calculation. It was showed in calculation results that the higher temperature the more reaction products. When reaction temperature below 828.07°C, the SiO₂ is only reaction product. So the method of synthetic reaction of SiO₂ in sputtering target of CoCrPt-SiO₂ is feasible, and reaction temperature must not higher than that characteristic temperature.

Abstract: In this study, CA fibers were fabricated using electrospinning technique with the mixture of acetic acid/acetone as the solvent system with the ratio of 3:1. The morphological structure of the fibers obtained was observed using scanning electron microscope (SEM). The SEM results showed that 10% of CA produced beads only, 12% of CA produced spindle beads with few fibers, 13% of CA produced fibers with few beads and 14% w/v concentration of CA produced continuous and smooth ribbon-like fibers with average diameter of 199.23nm.

Abstract: In this study, PCL microsphere has been synthesised using the double emulsion technique and a freeze dry technique. Bovine Serum Albumin (BSA) was added as a model protein and Hydroxyapatite (HA) to enhance osteoconductivity properties of the microsphere. Poly (caprolactone) (PCL)-based microspheres were synthesized and characterized. Microspheres were produced with 5%, 10%, and 15% (w/v) PCL solution (30mL) by dissolving different amounts of PCL in dichloromethane (DCM). Microspheres produced from 5% (w/v) PCL concentration had an average diameter of 100 – 120 μm. Bovine serum albumin (BSA) (0.04% w/v) and 10% w/w of HA powder were added into the microspheres produced from 5% (w/v) PCL concentration. The microsphere was then characterized using different techniques and in vitro release study of BSA was conducted. Prepared microsphere showed good potential for bone tissue engineering.