Search

The contact surface corrosion of friction high-strength bolt (FHSB) joints was analyzed to examine the characteristics of corrosion products and influence factors in steel bridges. Samples were selected from the Dongying Shengli Yellow River Bridge, which has been in service for 33 years. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were utilized to analyze the microscopic morphology and chemical composition of the corroded surface of the samples. The study identifies that construction quality issues accelerate corrosion of the contact surface and that the contact surface of the aluminum spraying layer transforms from rugged and dense to smooth and porous as corrosion increases. The findings also suggest that the friction coefficient of the FHSB connection node initially decreases and then increases as the corroded surface changes. Corrosion products contained S, Cl, Mn, Si, FeS, and their oxides, indicating that atmospheric, industrial, and Yellow River soil environments contribute to joint corrosion. The study proposes sandblasting and coating the corroded contact surface and deck steel plate with inorganic zinc-rich paint to prevent media penetration and delay substrate corrosion. Adopting ultra-high-performance concrete (UHPC) as the deck structure is also recommended to reduce top plate tensile stress, deck cracking, and media invasion. This study provides insights into the characteristics and mechanisms of FHSB joint corrosion to aid the maintenance, repair, and protection of steel bridges. [ABSTRACT FROM AUTHOR]

Magnesium oxide (MgO, pure) and zinc added MgO nanoparticles were synthesised by a simple microwave assisted solvothermal method. The concentrations of impurity used in the present work were 0.25 M and 0.50 M. All samples were annealed at 400°C for 1 h to improve the ordering. The prepared pure and zinc added magnesium oxide nanoparticles were characterised by powder X-ray diffraction (PXRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). PXRD studies of pure and zinc added MgO nanoparticles showed that all samples belong to crystalline nature with cubic structure. The grain size of all samples were determined from the XRD results and it belongs to nanometre scale. The EDS confirmed the presence of zinc, magnesium and oxide elements in the respective prepared samples. The scanning electron microscope images confirmed that the prepared samples possess nanometer dimensions. The electrical properties such as AC conductivity, dielectric constant and dielectric loss were measured at different temperatures in the different frequency range by involving the impedance analyser of all the prepared samples. [ABSTRACT FROM AUTHOR]

The paper reports the results of the analyses performed on a Roman quadrans dating back to the first century ad, belonging to a group of more than 8.000 coins found in the bed of river Tiber during an archaeological research in 1987–1988. The quadrans was examined by means of X‐ray diffraction, scanning electron microscopy, energy dispersion spectroscopy, and X‐ray photoelectron spectroscopy. Energy dispersion spectroscopy analytical results confirmed that the coin is made of pure copper. The compounds present in the patina have been identified through X‐ray diffraction. The spectrum is the overlapping of several peaks, and the results show that the patina substantially consists of malachite Cu2CO3(OH)2, cupric chloride CuCl2, and nantokite CuCl. X‐ray photoelectron spectroscopy only evidences nantokite because of the different analysis depths of the two techniques. This means that nantokite forms a thin outer layer in the concretion covering the quadrans. [ABSTRACT FROM AUTHOR]

A series of copper-based systems containing two different nanocomposites (Cu2O/CuO and Cu2O/Cu) was synthesized by the egg white assisted auto-combustion route. This method was distinguished by the simplicity of its steps, low cost, one-pot synthesis process at low temperature and, short time. The characterization of the as prepared nanocomposites was carried out by using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Scanning electron microscope (SEM) and transmission electron micrograph (TEM), Energy dispersive spectrometry (EDS) techniques. Surface and magnetic properties of the obtained systems were determined by using N2 adsorption/desorption isotherms at 77 K and the vibrating sample magnetometer (VSM) technique. XRD results confirmed the formation of Cu2O/CuO and Cu2O/Cu nanocomposites with different ratios of well crystalline CuO, Cu2O, and Cu phases. FTIR results of the combusted product displays the presence of both CuO and Cu2O, respectively. SEM/EDS and TEM results confirm the formation of a porous nanocomposite containing Cu, O, and C elements. The change in concentration of the oxygen vacancies at the surface or interface of both Cu2O/CuO and Cu2O/Cu nanoparticles resulted in different changes in their magnetization. Based on this study, it is possible to obtain nanocomposite-based copper with multiple valances by a simple and inexpensive route which can be suitable for the fabrication of different transition metal composites. [ABSTRACT FROM AUTHOR]