分类: 物理学 >> 核物理学 提交时间: 2023-11-16
摘要: The corrosion behavior of 316H stainless steel (SS) in the impure and purified NaCl-KCl-MgCl2 salt was investigated at 700 C . Results indicate that the main deleterious impurity induced corrosion in the impure salt was the absorbed moisture, present in the form of MgCl26H2O. 316H SS occurred severe intergranular corrosion with a corrosion depth of 130 m for 1000 h in the impure NaCl-KCl-MgCl2 salt. In contrast, the purification treatment of molten chloride salt by the dissolved Mg metal can remove the absorbed moisture, and the corresponding reactions were also discussed. As a result, the corrosiveness of NaCl-KCl-MgCl2 salt is reduced significantly. 316H SS occurred slight uniform corrosion with a depth of less than 5 m for 3000 h in the purified NaCl-KCl-MgCl2 salt.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Corrosion behavior of thermal sprayed Al and Al/nano-Al2O3 composite coatings in artificial seawater in the presence of Escherichia coli bacteria were investigated. A biofilm has been built-up on the coating surfaces following the colonization of the bacteria after 7 days soaking in the solution. The bacteria- related biofilm was used as the simplified model for examining the anti-biocorrosion performances of the marine coatings. The biofilm enhances the corrosion resistance of the Al-based coatings in early stages. Simulated results using equivalent circuit models provide direct electrochemical information about the liquid/surface interfaces, further elucidating the anti-biocorrosion mechanisms of the coatings.
提交时间: 2017-05-02
摘要: Nd24Fe65.5-xRMxB0.97Tb7.0Dy1.1Co1.0Al0.2Cu0.23 [RM=Nb, Zr, Ti; x=0.2, 0.4, 0.6] magnets with high property were prepared by powder metallurgy process. The measurements of high temperature magnetic properties indicate that the value of alpha [temperature c
提交时间: 2017-05-02
摘要: Here we report aluminum-alumina composite coatings fabricated by flame spraying for potential marine applications against both corrosion and wear. Microstructure examination suggested dense coating structures and the evenly distributed alumina splats form
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Four CrN coatings were deposited on 316L stainless steel by multi-arc ion plating. The tribological behaviors of the CrN coatings were investigated by ball-on-disk tribometer in seawater. The microstructure and wear track were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and profilometer. The result shows delamination is critical to wear failure of CrN coatings in seawater and micro- cracks play an important role in the evolution of delamination. The most effective approach to eliminate the delamination is fabricating a proper multilayer structure, which could limit crack propagation only to the layer. A comprehensive wear model is established.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Degradation of metals due to corrosion causes serious economic problems throughout the world, and different corrosion protection techniques are being used to extend the service life of metallic structures. It has been sug- gested that some microorganisms can inhibit electrochemical corrosion of metals. Here we isolated a new marine inhibitory bacterium, Vibrio neocaledonicus sp., and EIS results showed that the corrosion resistance of carbon steel increased by more than sixty fold in the presence of this bacterium. This is the highest corrosion inhibitory effect reported for bacteria and is comparable with some industrial coatings such as electroless Ni. This bacterium affected corrosion by the formation of an inhibitory layer on the metal surface in the first hours of attachment, with the consumption of oxygen by electron transport proteins. Extracellular polymeric substances produced by this bacterium also have a corrosion inhibitory effect. Thus we propose a new, natural, non-toxic, and cost- effective system for controlling corrosion processes using this bacterium or extracellular polymeric substances produced by this bacterium.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The Br and the (BH)max get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase.
分类: 核科学技术 >> 核科学与技术 提交时间: 2024-02-19
摘要: In this study, the interactions between a Ga-based liquid metal,GaInSn, and several metal materials, including pure metals (Ni and Ti) and alloys (316H stainless steel (SS) and GH3535), at 650 °C were investigated. The aim was to evaluate the corrosion performance and select a suitable candidate material for use as a molten salt manometer diaphragm in thermal energy storage systems. The results indicated that the alloys (316H SS and GH3535) exhibited less corrosion than pure metals (Ni and Ti) in liquid GaInSn. Ga-rich binary intermetallic compounds were found to form on the surfaces of all the tested metal materials exposed to liquid GaInSn, as a result of the decomposition of liquid GaInSn and its reaction with the constituent elements of the metal materials. The corrosion mechanism for all the tested materials exposed to liquid GaInSn was also investigated and proposed, which may aid in selecting the optimal candidate material when liquid GaInSn is used as the pressure-sensing medium
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-04-06
摘要: Cylindrical Nd-Fe-B magnets with different height reductions were prepared by hot deformation method. The inhomogeneity of the magnetic performance along the radial direction was revealed with a closed circuit B-H apparatus while that along the axial dire
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2024-02-20
摘要: The synergistic damage effect of irradiation and corrosion of reactor structural materials has been a prominent research focus. This paper provides a comprehensive review of the synergistic effects on the third- and fourth-generation fission nuclear energy structural materials used in pressurized water reactors and molten salt reactors. The competitive mechanisms of multiple influencing factors, such as the irradiation dose, corrosion type, and environmental temperature, are summarized in this paper. Conceptual approaches are proposed to alleviate the synergistic damage caused by irradiation and corrosion, thereby promoting in-depth research in the future and solving this key challenge for the structural materials used in reactors.
分类: 核科学技术 >> 裂变堆工程技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: To investigate the corrosion products of Cr in molten FLiNaK salt (46.5 mol% LiF11.5 mol% NaF42 mol% KF), the corrosion test of the pure metal Cr was performed in molten FLiNaK salt at 700 ℃ for 200 h. The FLiNaK salt after the corrosion test was thoroughly investigated by X-ray absorption near-edge structure spectroscopy, a transmission electron microscope, and X-ray diffraction. The results demonstrate that the predominant oxidation state of Cr in FLiNaK salt is Cr3+, and the main corrosion product in cooled FLiNaK salt is K2NaCrF6.
分类: 核科学技术 >> 裂变堆工程技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Nb can improve the resistance of Ni-based Hastelloy N alloy to Te-induced intergranular embrittlement. First-principles calculations are performed to research this mechanism by simulating the Ni(111) surface and the 5(012) grain boundary. The calculated adsorption energy suggests that Te atoms prefer diffusing along the grain boundary to forming the surface-reaction layer with Nb on surface of the Ni alloy. First-principles tensile tests show that the Nb segregation can enhance the cohesion of grain boundary. The strong Nb-Ni bonding can prevent the Te migration into the inside of the alloy. According to the Rice-Wang model, the strengthening/embrittling energies of Nb and Te are calculated, along with their mechanical and chemical components. The chemical bonds and electronic structures are analyzed to uncover the physical origin of the different effects of Te and Nb. Our work sheds lights on the effect of Nb additive on the Te-induced intergranular embrittlement in Hastelloy N alloy on the atomic and electronic level.
分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-05-09
摘要: In order to improve the mechanical durability, polyurethane (PU) needs to be modified to enhance the tribological and anti-corrosion properties. In this work, we fabricated a series of PU composite coatings reinforced with functionalized graphene (FG) and functionalized graphene oxide (FGO). The structural and morphological features of the composite coatings were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The results showed that the dispersion and compatibility of graphene and graphene oxide were improved via chemical modification. Moreover, they effectively enhanced the tribological and anti-corrosion properties of PU composite coatings, whose optimized additive range was between 0.25 wt% and 0.5 wt%. The effect depends on the balance of lubrication and barrier of fillers and cracks generated by them. Finally, in comparison with FG/PU coatings, the FGO/PU coatings exhibited a better tribological property but worse anti-corrosion property owing to the abundant oxygenated groups of GO. They led to stronger interfacial interactions between FGO and the PU matrix, but destroyed the graphene lattice structure to some extent.
提交时间: 2017-04-06
摘要: CrCN coatings were deposited using the multi-arc ion plating with different C2H2 flow rates. Microstructures, mechanical and tribological performances were systematically investigated. The results showed that the peak intensity correlated to Cr7C3 crystal
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: In this work, a novel electroactive silsesquioxane precursor, N-(3-triethoxysilylpropylureido) aniline tetramer (TESPAT), was synthesized via one-step coupling reaction between phenyl-capped aniline tetramer (AT) and 3-(triethoxysilyl)propyl isocyanate (TESPIC) under mild conditions. The chemical structure and electroactivity of the resulting silsesquioxane precursor were investigated by FTIR, NMR, UV-vis spectra, and cyclic voltammetry. Subsequently, the sol–gel reactions of TESPAT with triethoxymethylsilane (TEMS) at various compositions were carried out to achieve new electroactive siliceous hybrid materials with good thermal stability. Furthermore, polarization curves and electrochemical impedance spectroscopic (EIS) measurements indicated that the obtained hybrid materials exhibit remarkably enhanced corrosion protection on Q235 electrodes as compared to pure silica coating. The significantly improved anticorrosion performance is attributed to the redox catalytic capabilities of the AT units in the hybrid materials.