http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Microstructure Change of Nanosilica-Cement Composites Partially Exposed to Sulfate Attack
Qian Huang,Liang Zhao,Chenggong Zhao,Dongsheng Liu,Chaoqiang Wang 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3
The deterioration of cement composites containing nanosilica partially exposed to sulfate attack was studied, and the microstructure change of the composites was analysed by a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that nanosilica-cement composites had better sulfate resistance compared to plain cement composite under partial exposure to sulfate attack, and their sulfate resistance increased as the nanosilica content increased (in the range of 0 to 5 wt% replacing cement by weight). The main sulfate products were gypsum and ettringite within the surface and inner parts, respectively in both the immersed and evaporation portions of the nanosilica-cement composites, which was consistent with the plain cement composite. Thus, the incorporation of nanosilica did not change the distribution characteristics of the sulfate products within the composites partially exposed to sulfate attack. However, the addition of nanosilica reduced the amount of sulfate products in both the immersed and evaporation portions, and their amount decreased with the increase of nanosilica content. The evaporation portions of the composites suffered chemical sulfate attack rather than sulfate salt crystallization. Nanosilica-cement composites could be applied in real partial exposure environments containing sulfate ions.
A novel ceramic GEM used for neutron detection
Zhou, Jianrong,Zhou, Xiaojuan,Zhou, Jianjin,Jiang, Xingfen,Yang, Jianqing,Zhu, Lin,Yang, Wenqin,Yang, Tao,Xu, Hong,Xia, Yuanguang,Yang, Gui-an,Xie, Yuguang,Huang, Chaoqiang,Hu, Bitao,Sun, Zhijia,Chen, Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6
A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to <sup>3</sup>He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10<sup>2</sup>-10<sup>4</sup> in the mixture gas of Ar and CO<sub>2</sub> (90%:10%) and its energy resolution was about 27.7% by using <sup>55</sup>Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.