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Kong L.,Shijiazhuang University | Kong L.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Du Y.,Shijiazhuang University
Journal Wuhan University of Technology, Materials Science Edition | Year: 2015

The chemical and physical interactions in the interfacial transition zone (ITZ) between three different types of coarse aggregates (limestone, granite and basalt) and cement paste were investigated. The results show that all the aggregates are chemically active. Significant amounts of Ca2+, K+, and Na+ are absorbed by all the aggregates from the cement solution, granite and basalt also absorb significant amounts of OH− and release significant amounts of Si4+ into cement solution. The XRD, EDXA and pore structure results of the ITZ also show that more clinkers participate in the cement hydration in the ITZ of granite and basalt, and more hydrates are generated, hence resulting in a denser ITZ structure with a lower content of macropores. Although the limestone has the least activity, the connection between it and cement paste is tight, due to its rough surface and higher water absorption. Whereas the granite with smooth surface and lower water absorption has a loose connection with cement paste, many pores and cracks are visible, which is very detrimental to the concrete durability. © 2015, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg. Source


Li Y.,Shijiazhuang University | Sun X.,Shijiazhuang University | Sun X.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Wang Y.,Shijiazhuang University | And 3 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2014

SiO2/TiO2 nanoparticles doped with the different contents of La were prepared by a flow-together neutralization process and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and UV-Vis. The effects of La content and calcination temperature on the photocatalytic activity were investigated by the photodegradation of methyl orange under ultraviolet light irradiation. The possible mechanism was also analyzed primarily. The results of FT-IR showed that the Ti-O-Si and Ti-O-La bonds were formed at the interface of the coating layer and TiO2 particles. The presence of La3+ in SiO2/TiO2 could inhibit the phase transformation from anatase to rutile, and enhance the thermal stability of TiO2. The XRD patterns indicated that the percentage of rutile phase was still very low in La-doped SiO2/TiO2 sample at 800°C, which was equal to that at 120°C. The TEM images demonstrated that La-doped SiO2/TiO2 nanoparticles had uniform size distribution and polished surface. The absorption spectra indicated an extension of light absorption into the visible light region for the as-prepared samples. Among all the samples, the largest red-shift could be found in La doped SiO2/TiO2 sample with 3.0%(mole fraction) La, the band gap reduced from 2.98 to 2.41 eV. The photodegradation results showed that the composite powder with 3.0% La had the best ability of photo-degradation. In comparison with pure TiO2 nanoparticles, the photodegradation efficiency could be improved to 55.1% after reaction for 20 min. In addition, the effect of calcination temperature on the photocatalytic activity of undoped TiO2 was obvious, the photodegradation efficiency decreased from 69% to 10.7% for 25 min with calcination temperature increasing from 120 to 800°C. For La-doped SiO2/TiO2 sample, the effect of calcination temperature was negligible. Source


Du Y.,Shijiazhuang University | Du Y.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Zhang Y.,Shijiazhuang University | Wang J.,Shijiazhuang University | And 3 more authors.
Hecheng Shuzhi Ji Suliao/China Synthetic Resin and Plastics | Year: 2016

The novel non-toxic thermal stabilizer is prepared in this article by mixing process of gallic zinc/calcium(Zn/Ca) soap, gallic epoxy resin and o-cresol formaldehyde epoxy resin which are newly synthesized respectively. Evaluation of these compounds as thermal stabilizers for poly(vinyl chloride)(PVC) are measured. The results show that gallic Zn/Ca soap compound, gallic Zn/Ca soap mixing gallic epoxy resin compound and gallic Zn/Ca soap mixing o-cresol formaldehyde epoxy resin compound all exhibit greater thermal stability than that of traditional Zn/Ca stabilizers. Among which, the initial thermal degradation temperature of the sample containing gallic Zn/Ca soap mixing o-cresol formaldehyde epoxy resin compound (which has the best synergistic effect and thermally stable)rises by 41.6℃ than that of the sample containing traditional Zn/Ca stabilizers, meantime the static thermal stability time increases by 65%. © 2016, Research Institute of Beijing. All right reserved. Source


Si H.-Y.,Shijiazhuang University | Si H.-Y.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Wang L.-J.,Lanzhou University | Feng W.-J.,Shijiazhuang University | And 5 more authors.
New Journal of Chemistry | Year: 2015

Novel dendron encapsulated conjugated organic molecular wire (Den-OPE)-CdSe quantum dot (QD) nanostructures have been designed. By tailoring the size of dendrimers, different amounts of Den-OPEs could be attached to CdSe, which forms different sizes of core-shell Den-OPE-CdSe composites. With an increase in the size of dendrimers, the emission intensity of CdSe QDs increased due to the higher Förster energy transfer (FRET) efficiency from the bigger size Den-OPEs to CdSe QDs. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015. Source


Duan S.,Shijiazhuang University | Duan S.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Qin C.,Shijiazhuang University | Qin C.,Hebei Provincial Key Laboratory of Traffic Engineering Materials | Li B.,Shijiazhuang University
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Laser quenching was carried out on semi high speed steel(semi-HSS) 5Cr5MoSiV through synchronous powder feeding way with transverse flow CO2 laser processing machine, and microstructure and properties of the hardened layers were studied. The results indicate that the hardened layer of laser treated semi-HSS is divided into 4 regions as follow: fully quenched region, incomplete quenched region, the transition region and the substrate region. The microstructure of fully quenched region is martensite, retained austenite and a small amount of carbides. The hardness of the hardened layer increases by 1.5 times compared with the substrate. The change of laser power or scanning speed has a little influence on the surface hardness, but has significant influence on the depth of hardened layer. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved. Source

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