Mesoporous zirconia microspheres, with a diameter of 900 mm, were prepared as an inert accelerator driven system (ADS) transmutation element matrix by the sol-gel method. The purpose of mesopores is to improve the adsorption capacity of inert matrix fuel (IMF) for minor actinides. The study indicated that the mesoporous zirconia performance was improved after the microspheres were hydrothermally treated at 150 degrees C, the specific surface area increased from 28.29 m(2)/g to 61.28 m(2)/g, and hydrothermal treatment avoided the cracking of the microspheres. Pre-decomposition of the organics during the hydrothermal process stabilized the mesoporous structure. The average pore diameter of mesoporous microsphere was 14.3 nm. (C) 2016 Elsevier B.V. All rights reserved.

The effect of the strain of 316L stainless steel on its corrosion resistance in borate buffer solution was investigated by in site tensile test and the electrochemical impedance spectroscopy measurements. It was found that the corrosion resistance of the 316L stainless steel decreased with the increasing of in site strain. The lower corrosion resistance of the stainless steel during in site strain was mainly attributed to the higher doping concentration in passive film. Especially, with the increasing of in site strain, the concentrations of acceptor (i.e., cation vacancies) in the passive films significantly increased. More acceptor concentrations reduced the compactness of the passive film and its corrosion resistance. Moreover, two exponential relationships were found between in site strain and the charge transfer resistance of the passive film and between in site strain and total doping concentrations in passive film, respectively.

The effect of grain refinement on corrosion resistance of alloy 690 was investigated. The electron work function value of coarse grained alloy 690 was higher than that of nano/ultrafine grained one. The grain refinement reduced the electron work function of alloy 690. The passive films formed on coarse grained and nano/ultrafine grained alloy 690 in borate buffer solution were studied by potentiodynamic curves and electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the grain refinement improved corrosion resistance of alloy 690. This was attributed to the fact that grain refinement promoted the enrichment of Cr2O3 and inhibited Cr(OH)(3) in the passive film. More Cr2O3 in passive film could significantly improve the corrosion resistance of the nano/ultrafine grained alloy 690. (C) 2015 Elsevier B.V. All rights reserved.

The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α′-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α′-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution.

The ultrafine grained 2205 duplex stainless steel with an average grain size of 300nm was obtained by cold rolling down to 95% reduction in thickness and reversion annealing at 900°C for 200s. The ultrafine grained sample showed higher corrosion resistance than coarse grain one in borate buffer solution at room temperature, indicating that the passive film formed on the surface of the ultrafine grained 2205 duplex stainless steel is more protective. Comparing the doping concentrations between coarse grain and ultrafine grained samples from the Mott–Schottky plots, higher corrosion resistance of ultrafine grained sample was probably attributed to lower donor density and the thicker passive film in borate buffer solution. The results of electrochemical impedance spectroscopy were further supported by Raman spectra and XPS analysis.

The effect of sensitization at 600 degrees C on passive films on the surface of 2205 duplex stainless steel was investigated by the double loop electrochemical potentiokinetic reactivation technique, potentiodynamic polarization curves, electrochemical impedance spectroscopy and X-ray Photoelectron Spectroscopy. With the increasing of the passivation potential, the passivation property of the solid solution annealed sample decreased. Moreover, the corrosion resistance of the passive film on sensitized sample was lower than that on solid solution annealed sample, especially at 0.6 V-SCE. These results were supported by X-ray Photoelectron Spectroscopy and Mott-Schottky analyses. (C) 2015 Elsevier B.V. All rights reserved.

OBJECTIVE:To investigate the structure, mechanical and low temperature aging properties of colored dental zirconia ceramics.METHODS:5 graded colored dental zirconia ceramics were made by adding colorants and their combinations into a 3Y-TZP (tetragonal zirconia stabilized by 3mol% yttrium) powder, the green body were compacted at 200 MPa, pre-sinter at 1,050 degrees C and maintained for 2 h, then densely sintered at 1,500 degrees C for 2 h. Specimens were cut from each of the 5 graded colored blocks. Physical, mechanical properties as well as chemical stability were tested, microstructure were observed, crystalline phase were identified by X-ray diffraction (XRD), aging properties were assessed by measurement of the relative content of monoclinic phase and bending strength testing.RESULTS:The overall density of colored zirconia ceramics was over 99.7%, linear shrinkage was about 20%, while thermal expansion coefficient was about 11 x 10(-6) x degrees C(-1), the crystalline phase was tetragonal, bending strength was over 900 MPa which was slightly lowered than that of the uncolored zirconia, fracture toughness was slightly higher. Good chemical stability in acetic acid was observed. After aging treatment, tetragonal-to-monoclinic phase transformation was detected up to 40%, while bending strength was not significantly degraded.CONCLUSION:The results showed that colored 3Y-TZP ceramics presented good mechanical properties even after aging treatments, and was suitable for dental clinical use.

The setting behavior of fast-setting calcium phosphate cement (FSCPC) with mineral phase of bone was investigated to evaluate the possible value of the CPC for medical and dental application. Various aspects of the setting behavior such as setting time, mechanical strength and phase change of cement with time were measured by the Vicat needle method, diametral tensile strength measurement, and quantitative powder X-ray diffraction (XRD) analysis, respectively. The change of microstructure during the setting process was observed by Scanning Electron Microscope (SEM). The setting time of the CPC was 10-15min. As a result of its fast setting, set specimens of FSCPC showed high mechanical strength. Powder XRD analysis' revealed faster conversion of FSCPC into HAP. SEM observation showed that the specimens are mainly formed with micropores and crystallites, and the phase composition of the set specimens is mainly low-crystallinity HAP at last.

ZnO-Al2O3-SiO2 glasses with different surface conditions were surface crystallized by different heat treatment process. Differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and scanning electronic microscope (SEM) were used to investigate the crystallization behavior of glasses, the crystalline components and microstructure of the as-got glass-ceramics. According to the DTA results, different heat treatment processes of surface crystallization on the glass were adopted. The SEM results show that surface conditions of glasses are important for the surface crystallization, and the thickness of surface crystalline layer increases with heat treatment time.