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排序方式: 共有2885条查询结果,搜索用时 15 毫秒
81.
Xianzi Lv Quantong Jiang Jie Zhang Jianxin Zhang Zaiwang Huang Jizhou Duan Baorong Hou 《Materials》2020,13(23)
The electrochemical behaviors of the Ni-base superalloy CMSX-4 were carried out in 3.5 wt.% NaCl solution using electrochemical technique. The electrochemical corrosion process was divided into four stages, and reactions at the alloy surface and corrosion morphology at each stage were analyzed. The passivity mechanism at the stable passivation stage and the occurrence of pitting corrosion at the transpassivation state were discussed especially. The corrosion parameters including Ecorr, Epass, ipass and Epit were compared at different temperatures to reveal the relationship between the temperature and the corrosion resistance properties. The corrosion products were investigated by the aid of X-Ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). By designing different preoxidation procedures, the corrosion mechanism of oxide scales was analyzed for the preoxidized samples. 相似文献
82.
In this paper, effects of sodium phosphate (Na3PO4) and sodium nitrite (NaNO2) on the pitting corrosion of X70 carbon steel in 0.10 mol/L NaCl solution were investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) method, scanning electron microscope (SEM) and scanning electrochemical microscope (SECM). The SECM equipment was used to observe the dynamic processes of the pitting corrosion in situ. Na3PO4 or NaNO2 in the sodium chloride solution decreased the local anodic dissolution and increased the pitting resistance of the specimen. By analysis and comparison, it can be concluded that the inhibition effect of Na3PO4 is mainly due to the formation of a salt film, while the corrosion inhibition of NaNO2 is principally attributed to a protective oxide film on the electrode surface. 相似文献
83.
Jun Ding Sheng-Lai Zhang Quan Tong Lu-Sheng Wang Xia Huang Kun Song Shi-Qing Lu 《Materials》2020,13(24)
The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni3Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0–60° and 60–90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni3Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni3Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni3Al layers are dominated by twinning area growth resulting from extended dislocations. 相似文献
84.
Xiaoli Song Juan Wang Xiadan Luo Chunlan Xu Aiping Zhu Rong Guo 《Journal of biomaterials science. Polymer edition》2014,25(10):1062-1075
Polymers with targeted ligands are widely used as the anti-cancer drug delivery materials. For applications of chitosan as an anti-liver cancer drug delivery, poly (ethylene glycol)/lactobionic acid-grafted chitosan (PEG/LA-CS) was prepared and investigated since lactobionic acid can be specifically recognized by the hepatocytes. The structure of the PEG/LA-CS was characterized by Fourier transform infrared spectrometry and elemental analysis. The self-assembly behaviors of the PEG/LA-CS were monitored by steady-state fluorescence spectroscopy and electronic transmission microscope. The protein adsorption of the PEG/LA-CS was detected with bovine serum albumin (BSA) by electrochemical impedance spectroscopy. The results showed that the PEG/LA-CS almost did not adsorb protein. To study the effects of PEG/LA-CS on the structure of BSA, the interactions between the PEG/LA-CS and BSA were detected by ultraviolet spectrum, fluorescence spectrum, and circular dichroism. All the data gave one result that BSA maintained its original folded confirmation in PEG/LA-CS solution. The hemocompatibility of PEG/LA-CS was investigated by observing the effects of PEG/LA-CS on the hemolysis rate and the plasma recalcification time (PRT). The results showed that the PRT was prolonged greatly and the hemolysis rate was less than 5%. Furthermore, PEG/LA-CS also showed good cytocompatibility with K562, Hep G2, and LO2 cells. Therefore, the PEG/LA-CS is believed to have great potential for producing injectable anti-liver cancer drug delivery. 相似文献
85.
P. Chakraborty Banerjee Ren Ping Woo Sam Matthew Grayson Amrita Majumder R. K. Singh Raman 《Materials》2014,7(8):6092-6104
The protective performance of zeolite coating on AZ91D magnesium alloy was evaluated using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) in 0.1 M sodium chloride solution (NaCl). Electrical equivalent circuit (EEC) was developed based upon hypothetical corrosion mechanisms and simulated to correspond to the experimental data. The morphology and the chemical nature of the coating were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Post corrosion morphologies of the zeolite coated and the uncoated AZ91D alloy were investigated using SEM. The corrosion resistance of the zeolite coated specimen was at least one order of magnitude higher than the uncoated specimen. 相似文献
86.
Je-Hwang Ryu Gi-Ja Lee Wan-Sun Kim Han-Eol Lim Mallory Mativenga Kyu-Chang Park Hun-Kuk Park 《Materials》2014,7(3):1975-1983
We demonstrate the fabrication of an all-carbon electrode by plasma-enhanced chemical vapor deposition for use in flexible electrochemical applications. The electrode is composed of vertically aligned carbon nanotubes that are grown directly on a flexible graphite foil. Being all-carbon, the simple fabrication process and the excellent electrochemical characteristics present an approach through which high-performance, highly-stable and cost-effective electrochemical applications can be achieved. 相似文献
87.
Mastura Shafinaz Zainal Abidin Tahsin Morshed Hironori Chikita Yuki Kinoshita Shunpei Muta Mohammad Anisuzzaman Jong-Hyeok Park Ryo Matsumura Mohamad Rusop Mahmood Taizoh Sadoh Abdul Manaf Hashim 《Materials》2014,7(2):1409-1421
The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100) substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100°C for 1 s. All annealed samples show single crystalline structure in (100) orientation. A significant appearance of Si-Ge vibration mode peak at ~00 cm−1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of SixGe1−x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance. 相似文献
88.
Jun-Sik Kim Jae-Pyeong Ahn Yang-Hee Kim Kyung Won Seo Homayoun Zadeh Seong-Hun Kim 《The Angle orthodontist》2019,89(2):292
Objectives:To evaluate nanoscale molecular interactions in the interface between human bone and orthodontic titanium implants.Materials and Methods:An orthodontic implant (sandblasted with large grit and with an acid-etched surface treated with Ti6A14V alloy) retrieved from the mandible of human after 2 months of healing was used to analyze the molecular interactive mechanism between the implant and the surrounding bone tissue. To preserve the natural state of the sample as much as possible, cryofixation and scanning electron microscope/focused ion beam milling without any chemical treatment were used during sample preparation. Atom probe tomography was used to investigate the chemical composition and structure at the interface between the implant and human bone tissue.Results:Three-dimensional (3D) reconstruction of the whole sample revealed a 20 × 50-nm2 plate-like bony element diffusion layer in the sample. The iso concentration analysis of the diffusion layer indicated that the bony element, calcium, and the implant element, titanium oxide, were interspersed with each other. Detailed ionic distribution was illustrated by 3D reconstruction with partial region of interest and one-dimensional concentration profiles of the implant-bone interface.Conclusions:The study results advance nanoscale understanding of osseointegration and suggest a potential nanostructure for increasing bond strength of biomaterials to bone. 相似文献
89.
90.
Gruener S Sadjadi Z Hermes HE Kityk AV Knorr K Egelhaaf SU Rieger H Huber P 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(26):10245-10250
During spontaneous imbibition, a wetting liquid is drawn into a porous medium by capillary forces. In systems with comparable pore length and diameter, such as paper and sand, the front of the propagating liquid forms a continuous interface. Sections of this interface advance in a highly correlated manner due to an effective surface tension, which restricts front broadening. Here we investigate water imbibition in a nanoporous glass (Vycor) in which the pores are much longer than they are wide. In this case, no continuous liquid-vapor interface with coalesced menisci can form. Anomalously fast imbibition front roughening is experimentally observed by neutron imaging. We propose a theoretical pore-network model, whose structural details are adapted to the microscopic pore structure of Vycor glass and show that it displays the same large-scale roughening characteristics as observed in the experiment. The model predicts that menisci movements are uncorrelated, indicating that despite the connectivity of the network the smoothening effect of surface tension on the imbibition front roughening is negligible. These results suggest a new universality class of imbibition behavior, which is expected to occur in any matrix with elongated, interconnected pores of random radii. 相似文献