scholarly journals Analysis of the specific vibration modes of goethite (α-FeOOH) by terahertz spectroscopy and calculations of the vibration frequencies of a single molecule using density functional theory

2018 ◽  
Vol 8 (1) ◽  
pp. 29 ◽  
Author(s):  
Ryo Hasegawa ◽  
Takashi Kimura ◽  
Tadao Tanabe ◽  
Katsuhiro Nishihara ◽  
Akira Taniyama ◽  
...  
Keyword(s):  
Single Molecule ◽  
Density Functional ◽  
Steel Sheet ◽  
Corrosion Products ◽  
Metal Corrosion ◽  
Galvanized Steel ◽  
Molecular Vibration ◽  
Thz Spectroscopy ◽  
Vibration Modes ◽  
Terahertz Waves

Steel sheet with an insulator to prevent corrosion is used for various purposes including in building and car manufacture. Terahertz waves, for which insulators are highly permeable and metal surfaces are highly reflective, have been studied in order to establish a new inspection technology for these steel plates. In our previous research, spectroscopic measurements in the 1.0-4.0 THz range, generated by a GaP crystal, were carried out in order to collect information on the infrared activity of the metal corrosion products formed on Zn-Al hot-dip galvanized steel sheet. In the previous work, the infrared activity of Fe-based corrosion products was not examined. To examine these products, we conducted THz spectroscopy on goethite (α-FeOOH) in the range from 8.4 to 11.0 THz, generated by a GaSe crystal. The results of Attenuated Total Reflectance (ATR) FTIR spectral measurements and molecular vibration calculations were analyzed, on the basis of which the natural vibration modes of α-FeOOH in the THz frequency range were assigned.

Molecular Vibration Theoretical Analysis of Two-Dimensional Photoelectric Conversion Material WSe2

2018 ◽  
Vol 765 ◽  
pp. 16-23
Author(s):  
Rui Zhang ◽  
Hong Bo Li ◽  
Guo Qiang Hao ◽  
Wen Bo Liu ◽  
Xiao Jun Ye ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Density Functional ◽  
Molecular Vibration ◽  
Raman Shift ◽  
Vibration Modes ◽  
Photoelectric Conversion ◽  
Functional Theory ◽  
Conversion Materials ◽  
Direct Band ◽  
New Generation

Monolayer WSe2is flexible, nearly transparent and direct band-gap semiconductor with the potential to be new generation thin film photoelectric conversion materials. The molecule vibration modes of monolayer and bulk WSe2was analyzed by factor group and the phonons dispersion and vibration frequency was calculated by first-principles based on density functional theory. Furthermore, the comparison between the above calculations and experiment values of Raman shift of monolayer and bulk WSe2was made to verify the accuracy of theoretical analysis and theoretically explain the differences of monolayer and bulk WSe2materials in Raman spectra.

Effective corrosion inhibition performance of La(NO3)3 doped sol-gel coating on galvanized steel sheet

2014 ◽  
Vol 61 (6) ◽  
pp. 370-379 ◽  
Author(s):  
Akshya K. Guin ◽  
M. Bhadu ◽  
Mahua Sinhababu ◽  
Ankita Mundhara ◽  
T.K. Rout ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Steel Sheet ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Sol Gel ◽  
Galvanized Steel ◽  
Molecular Vibration ◽  
Suitable Alternative ◽  
Content Type ◽  
Passivation Treatment

Purpose – The aim of this work was to study the effect of La(NO 3 ) 3 on the corrosion behavior of sol-gel coating prepared by hydrolysis of 3-glycidoxypropyl)methyldiethoxysilane and 3-aminopropyltriethoxysilane. Generally, galvanized steel is subjected to a hexavalent chromium passivation treatment. Hexavalent chromium passivation is not an environment friendly product and researchers are looking for a suitable alternative for chromium passivation treatment. Some of the potential alternatives are silicate conversion coating or the use of silane-based coatings. In this context, sol-gel coating was investigated as a potential replacement for hazardous hexavalent chromium passivation treatment. Design/methodology/approach – The sol-gel film was deposited on galvanized steel sheet by the dip coating method. The molecular vibration and chemical properties of sol-gel solution and coated films were obtained by infrared spectroscopy. Images from a scanning electron microscope were obtained to characterize the morphology of the film. The corrosion resistance of the coated samples was evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves and salt spray tests. Findings – The results indicated that La(NO 3 ) 3 -doped coatings were more resistance to corrosion than undoped coating. The coating doped with 0.5 per cent La(NO 3 ) 3 offered improved corrosion protection due to the inhibitive action of the La3+ ion. Originality/value – This result can provide a reference for the development of chromium-free passivation for galvanized sheeting.

Study on shear performance and calculation method for self-pierce riveted joints in galvanized steel sheet

2021 ◽  
Vol 161 ◽  
pp. 107490
Author(s):  
Zhiqiang Xie ◽  
Ailin Zhang ◽  
Weiming Yan ◽  
Yanxia Zhang ◽  
Tingting Mu ◽  
...  
Keyword(s):  
Calculation Method ◽  
Steel Sheet ◽  
Galvanized Steel ◽  
Riveted Joints ◽  
Shear Performance

The Effect of Composition and Microstructure on Corrosion Behavior in SST of Zn-Al-Mg Galvanized Steel Sheet

2013 ◽  
Vol 442 ◽  
pp. 64-69
Author(s):  
Feng Li ◽  
Jia Shun Lv ◽  
Hong Gang Yang ◽  
Fang Zhou ◽  
Leng Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Steel Sheet ◽  
Alloy Composition ◽  
Element Distribution ◽  
Galvanized Steel ◽  
Good Corrosion Resistance ◽  
Excellent Corrosion Resistance

Z11A3M, Z6A3M, Z1.6A1.6M, Z1A1M and Z1M coating samples were prepared in HDPS by traditional continuous hot dipping method. The microstructure, element distribution and phase was analyzed by SEM, EPMA and XRD. The corrosion resistance was checked in SST. The result was, MgZn2 and eutectic could be found in all ZAM coating. The ZAM coatings showed excellent corrosion resistance in SST than GI. The corrosion resistance was 4.1 to 11 times of GI. There was no strong relativity between alloy composition and corrosion resistance due to Mg enrichment on the surface of coating. Edge-unsealed ZAM samples showed good corrosion resistance than edge-sealed sample.

scholarly journals The formation of formates: 3a review of metal formates on heritage objects

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Gerhard Eggert ◽  
Andrea Fischer
Keyword(s):  
Degradation Products ◽  
Dominant Role ◽  
Copper Alloys ◽  
Wood Products ◽  
Corrosion Products ◽  
Metal Corrosion ◽  
Irreversible Damage ◽  
Preventive Conservation ◽  
Calcium Formate ◽  
Metal Formates

AbstractMetal formates sometimes occur as degradation products on heritage objects due to the use of wood products or other sources of formic acid and formaldehyde. They are often related to alkaline surfaces which transform formaldehyde directly into formate. The dominant role of formate on alkaline surfaces, for example in glass-induced metal corrosion (GIM) or calcium carbonate degradation, was explored in the Stuttgart research on rare heritage corrosion products. This review discusses these findings together with those from the literature: ocurrences of sodium and potassium formate on glass, calcium formate and calcium acetate-formate phases on calcareous materials, magnesium formate on Sorel cement and dolomitic sandstone, lead formate on metal and pigments, cadmium formate on coated objects, as well as various copper and zinc formates on copper alloys. In the latter cases, formates dominate as glass-induced metal corrosion products. The formation of formates constitutes irreversible damage, degrading the material of heritage objects. Therefore, preventive conservation needs to remove all sources of carbonyl pollutants in order to avoid such corrosion.

scholarly journals Remedial Treatment of Corroded Iron Objects by EnvironmentalAeromonasIsolates

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Wafa M. Kooli ◽  
Thomas Junier ◽  
Migun Shakya ◽  
Mathilde Monachon ◽  
Karen W. Davenport ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Building Materials ◽  
Solid Phase ◽  
Corrosion Products ◽  
Metal Corrosion ◽  
Economic Losses ◽  
Cytotoxic Activities ◽  
Iron Corrosion ◽  
Pathogenic Potential ◽  
Wide Range

ABSTRACTUsing bacteria to transform reactive corrosion products into stable compounds represents an alternative to traditional methods employed in iron conservation. Two environmentalAeromonasstrains (CA23 and CU5) were used to transform ferric iron corrosion products (goethite and lepidocrocite) into stable ferrous iron-bearing minerals (vivianite and siderite). A genomic and transcriptomic approach was used to analyze the metabolic traits of these strains and to evaluate their pathogenic potential. Although genes involved in solid-phase iron reduction were identified, key genes present in other environmental iron-reducing species are missing from the genome of CU5. Several pathogenicity factors were identified in the genomes of both strains, but none of these was expressed under iron reduction conditions. Additionalin vivotests showed hemolytic and cytotoxic activities for strain CA23 but not for strain CU5. Both strains were easily inactivated using ethanol and heat. Nonetheless, given a lesser potential for a pathogenic lifestyle, CU5 is the most promising candidate for the development of a bio-based iron conservation method stabilizing iron corrosion. Based on all the results, a prototype treatment was established using archaeological items. On those, the conversion of reactive corrosion products and the formation of a homogenous layer of biogenic iron minerals were achieved. This study shows how naturally occurring microorganisms and their metabolic capabilities can be used to develop bio-inspired solutions to the problem of metal corrosion.IMPORTANCEMicrobiology can greatly help in the quest for a sustainable solution to the problem of iron corrosion, which causes important economic losses in a wide range of fields, including the protection of cultural heritage and building materials. Using bacteria to transform reactive and unstable corrosion products into more-stable compounds represents a promising approach. The overall aim of this study was to develop a method for the conservation and restoration of corroded iron items, starting from the isolation of iron-reducing bacteria from natural environments. This resulted in the identification of a suitable candidate (Aeromonassp. strain CU5) that mediates the formation of desirable minerals at the surfaces of the objects. This led to the proof of concept of an application method on real objects.

scholarly journals Mono- and Bi-Molecular Adsorption of SF6 Decomposition Products on Pt Doped Graphene: A First-Principles Investigation

2018 ◽  
Vol 8 (10) ◽  
pp. 2010 ◽  
Author(s):  
Yongqian Wu ◽  
Shaojian Song ◽  
Dachang Chen ◽  
Xiaoxing Zhang
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Energy Gap ◽  
Adsorption Parameters ◽  
Functional Theory ◽  
Decomposition Products ◽  
Before And After ◽  
Doped Graphene ◽  
Sf6 Decomposition

Based on the first-principles of density functional theory, the SF6 decomposition products including single molecule (SO2F2, SOF2, SO2), double homogenous molecules (2SO2F2, 2SOF2, 2SO2) and double hetero molecules (SO2 and SOF2, SO2 and SO2F2, SOF2 and SO2F2) adsorbed on Pt doped graphene were discussed. The adsorption parameters, electron transfer, electronic properties and energy gap was investigated. The adsorption of SO2, SOF2 and SO2F2 on the surface of Pt-doped graphene was a strong chemisorption process. The intensity of chemical interactions between the molecule and the Pt-graphene for the above three molecules was SO2F2 > SOF2 > SO2. The change of energy gap was also studied and according to the value of energy gap, the conductivity of Pt-graphene before and after adsorbing different gas molecules can be evaluated.

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