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Lv G.C.,University of Science and Technology of China | Wang Z.S.,China Science and Technology Museum | Wu L.M.,University of Science and Technology of China | Xu C.,Beijing University of Chemical Technology
Anti-Corrosion Methods and Materials | Year: 2011

Purpose: The purpose of this paper is to investigate the microstructures, slag inclusions, morphology and composition of ancient Chinese iron coins exhumed from Emei Mountain and Baoji after 818-966 years of being imbedded underground. Design/methodology/approach: Metallography, scanning electron microscopy, energy dispersive spectrometry, X-ray photoelectron spectrometry and Fourier transform infrared spectroscopy were employed. Findings: The results showed that archaeological coins exhibited characteristics of a typical hypoeutectic white cast iron, with slag inclusions of FeS strips and phosphate. Porous or hexagonal platey corrosion products were discovered on the archaeological iron coin, which were mainly identified as Fex, FeOOH, Fex(OH)1-xCO3 and Fex(OH)1-xSO4. The possible corrosion mechanisms for the iron coins were discussed based on the corrosion products. Originality/value: This study revealed the characterization of corrosion products on archaeological iron coins and may provide guidance for the preservation of archaeological iron. © Emerald Group Publishing Limited. Source

Qu D.-D.,Beijing Institute of Technology | Qu D.-D.,Beijing Aerospace Times Laser Inertial Technology Co. | Zhao Y.-J.,Beijing Institute of Technology | Ren Y.,China Science and Technology Museum
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2010

Foldable segmented mirrors satisfy the requirement of next generation telescope which requires larger, lighter and foldable. Detecting the piston error between individual segments with high accuracy is critical to avoiding the image degradation due to segments misalignment with large mirrors. It is also critical to realize the grand scale of the segment mirror. The relationship of piston error and the distance of the main peak point of diffractive spot from the center point of image was proved to be linear within one wavelength range. A method to detect the piston error based on the location of the main peak of diffraction theory was presented. The optical system was simple and the measurement accuracy was high. The accuracy of the peak location was required high enough to satisfy the requirement for piston detecting of segmented mirrors. A peak location method based on Gaussian fitting was used and the location accuracy may arrive to 600 nm on the condition of 10 sampling points or so with the sample interval of 5 μm. The experimental results show that it is a valid method to detect the piston error of the segmented mirrors. The measurement accuracy of piston can achieve within one wavelength range. Source

Zhou X.-J.,Finnish Center for Radiation and Nuclear Safety | Du J.,RAE KLH Technologies Beijing Co. | Tang G.,China Science and Technology Museum | Chen D.-L.,Finnish Center for Radiation and Nuclear Safety
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2013

The high risk transportable radiation source is widely used in industrial radiographic inspection and radioactivity logging industries. The radiological protection of the potential hazard radiation source is attracted more and more attentions now. As one of the effective technical method of radiation source management, the paper introduced and studied the design of front-end hardware and the software management platform of the transportable radiation source in detail. Source

Meng G.,Qinghai University | Gao D.,Qinghai University | Gao D.,Zhejiang University | Wang S.,Qinghai University | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

Along with the booming development of the photovoltaic industry, the later maintenance of photovoltaic power station and the improvement of photovoltaic power generation efficiency have gradually become the focus of attention. Under the condition of blown sand in high altitude desert areas, dust accumulation on the surface of solar panel has become one of the most significant factors which influences the consistency and efficiency of photovoltaic power station. The effects of dust deposition on photovoltaic conversion efficiency and dust removal methods were studied. The mechanism of dust particle adhesion was analyzed at first in this paper. Due to the surface free energy of the dust particle and solar panel, they interacted. The van der Waals force between spherical dust particles and the panel was derived from Lifshitz's macro molecular interaction theory and the order of magnitudes van der Waals force was calculated. The electrostatic image force was simulated based on two known dust charge empirical expressions. The relationship between the radius of dust particle and the double layer electrostatic force was investigated by taking different values of the contact potential difference, which ranged from 0 to 0.5 V. Compared with the dust particle, the solar panel surface can be taken as an infinite disk. The relationship between the parameters and electric field force was obtained. Meanwhile, the gravity of dust particle was analyzed when the photovoltaic panels were mounted with an angle with respective to the horizontal plane. Through the analyses of all interactive forces, the conclusions that Van der Waals force of dust particle increased with increasing of the surface free energy were drawn. The dust particle radius ranged from 0.2×10-6 to 40×10-6 m, and the distance between molecules ranged from 10-9 to 10-7 m. Combined with Lifshitz constant (0.96-14.4 eV), the magnitude of dust van der Waals force was calculated as 10-10-10-9 N. The magnitudes of electrostatic image force and double layer electrostatic force were calculated as 10-13-10-12 N based on the charges (10-18-10-16 C) of dust surface and the contact potential difference (0-0.5 V). The radius of dust and the distance between molecules had smaller effects on the electrostatic image force and double layer electrostatic force than electrostatic image force. The dust particle radius R had no effects on the electric field strength. The electric field force increased with the increasing of R. The distance between molecules didn't affect the electric field force. The magnitude of electric field force was calculated as 0-10-13 N. The gravity of dust particle was affected by the radius and density of dust particle, and its magnitude was approximated as 10-10-10-9 N. The interactions between the dust particles were more complex, which was affected by the numbers of particles, the porous ratio, particle clearance and radius. Through analyzing all interactions between dust particle and solar panel surface, it is concluded that van der Waals force > gravity > electrostatic force when the dust radius was smaller (R<20×10-6 m), and gravity > van der Waals force > electrostatic force when the dust radius was larger (R>20×10-6 m). The adhesion force between the dust particle and solar panel surface increased with the increasing of dust radius, and its magnitude ranged from 10-10 to 10-8 N. In the dry and windy desert area, the combination of gravity and van der Waals force plays an important role without considering the chemical interactions. Source

Mei L.,University of Science and Technology of China | Liao L.,University of Science and Technology of China | Wang Z.,China Science and Technology Museum | Xu C.,Beijing University of Chemical Technology
Advances in Materials Science and Engineering | Year: 2015

Alpha, beta, gamma, and delta hydroxyl ferric oxides (FeOOH), as the most common rust layers on iron surface, play different roles in iron preservation. Using modern surface analysis technologies such as X-ray diffraction (XRD), infrared spectra (IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), we studied the interactions between these four types of synthetic FeOOH and phosphoric and tannic acid of different concentrations and proportions. A 3% tannic acid + 10% phosphoric acid + FeOOH was the most suitable formula for rust stabilizer and its reaction products were made up of iron phosphate and chelate of iron and tannin. This research provided technical basis in distinguishing FeOOH and selecting rust layer stabilizer for the preservation of iron, especially iron cultural relics. © 2015 Lefu Mei et al. Source

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