Anisotropic Mechanical Properties of 2-D Materials

Mapping Intimacies ◽

10.5772/intechopen.96598 ◽

2021 ◽

Author(s):

Qiang Li

Keyword(s):

Grain Boundaries ◽

2D Materials ◽

Wide Spectrum ◽

Alloy Coating ◽

Hexagonal Structure ◽

Synthetic Methods ◽

Mechanical Anisotropy ◽

Al Alloy ◽

Crystalline Materials ◽

Unit Cells

While prior reviews and research articles focused on the various synthetic routes and microstructural controls of 2D nanomaterials as well as their functional applications, this chapter discloses the anisotropic behaviors of 2D materials and puts emphasis on the mechanical anisotropy of three distinct 2D materials, namely graphene, MoS2 and Al alloy coating, representative of carbon, inorganic and metallic 2D crystalline materials. Except for the relatively low interlayer cohesive stress, the in-plane anisotropy of the former two materials classes is subjected primarily to the hexagonal structure of the unit cells of the graphene and MoS2. The anisotropy of metallic thin films with high-density grain boundaries with preferential directionality, rendered by the non-equilibrium synthetic methods, results from both the conventional Taylor factor and the directionality of the grain boundaries. Despite 2D materials’ wide spectrum of applications, such as electronics, energy devices, sensors, coating etc., the mechanical anisotropy could be critical for certain mechanical applications, such as friction, and provide instructions on the durability, reliability and property optimization in the various applications of different 2D materials.

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Low-pressure cold metal spray coatings for repair and protection of marine components

10.24868/issn.2515-818x.2018.043 ◽

2018 ◽

Author(s):

M Pal

Keyword(s):

Marine Environment ◽

Alloy Coating ◽

Al Alloy ◽

Metallic Coatings ◽

Material State ◽

Paint Coatings ◽

And Performance ◽

Cuzn Alloy ◽

Cold Metal ◽

Metal Spray

The marine environment is hostile to most engineering materials, a combination of in-service wear and exposure to marine environment leads to an accelerated material degradation. Insufficient or poor protection of the substrates further assists the accelerated material degradation in marine environment. There is a direct relationship between the material-state of a ship and its operational capability, readiness, and service life. The current state-of-the-art practice is to use paint-based coatings to maintain the material-state of ships. However, the protection offered by paint coatings is usually brief due to inherent permeability and low damage tolerance of these coatings. For this reason, the paint coatings require renewal at regular intervals, typically less than 5-years, to maintain a minimum level of protection from the marine environment. The need for regular painting of ships results in a significant negative impact on the through-life availability, operational capability/readiness, and the cost of maintenance/operation of naval ships. Therefore, the fleet owners and operators should look beyond the conventional paint-based coatings to achieve significant breakthrough improvements in maintaining and enhancing the material-state of naval ships. Metallic coatings, if selected and applied appropriately, will outperform the paint coatings in the marine environment. Historically, the cost and performance of metallic coatings, mainly thermal metal spray (TMS) coatings, prevented their widespread use in the marine industry. The TMS coatings also have their own inherent application and performance related limitations that are widely reported in the literature. However, the cold metal spray (CMS) coating process can overcome the application and performance related limitations that are typically associated with the TMS coatings, therefore creating an opportunity for widespread use of metallic coatings in shipbuilding and fleet upkeep/maintenance. In this paper, the ability of low-pressure (LP-CMS) coatings to repair and reclaim damaged marine components, and application of functional coatings to improve in-service damage tolerance of the damaged/new components is investigated. The results of the investigation show that two LP-CMS coatings, Al-alloy and CuZn-alloy, can be used to repair and preserve both new and damaged components. The accelerated salt-spray and natural immersion corrosion testing of the LP-CMS coatings showed that each coating will be better suited to a particular operational environment, i.e. CuZn-alloy coating performed well in both immersion and atmospheric corrosion environments, whereas Al-alloy coating performed well only in atmospheric corrosion environment.

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Breaking the acoustic diffraction limit with an arbitrary shape acoustic magnifying lens

Scientific Reports ◽

10.1038/s41598-021-92297-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ali Abdolali ◽

Hooman Barati Sedeh ◽

Mohammad Hosein Fakheri ◽

Chen Shen ◽

Fei Sun

Keyword(s):

Arbitrary Shape ◽

Design Principle ◽

Focused Ultrasound ◽

Effective Medium Theory ◽

Wide Spectrum ◽

Diffraction Limit ◽

Far Field ◽

Biomedical Sensors ◽

Focused Ultrasound Surgery ◽

Unit Cells

AbstractBased on the transformation acoustics methodology, the design principle for achieving an arbitrary shape magnifying lens (ASML) is proposed. Contrary to the previous works, the presented ASML is competent of realizing far-field high resolution images and breaking the diffraction limit, regardless of the position of the utilized sources. Therefore, objects locating within the designed ASML can be properly resolved in the far-field region. It is shown that the obtained material through the theoretical investigations becomes an acoustic null medium (ANM), which has recently gained a significant attention. Besides the homogeneity of ANM, which makes it an implementable material, it is also independent of the perturbation in the geometry of the lens, in such a way that the same ANM can be used for different structural topologies. The obtained ANM has been implemented via acoustics unit cells formed by membranes and side branches with open ends and then was utilized to realize an ASML with the aid of effective medium theory. It is shown that the far-field results of an ideal ASML abide well with the results of the implemented sample, validating the proposed design principle. The presented acoustic magnifying lens has a wide spectrum of possible applications ranging from medical imaging, and biomedical sensors to focused ultrasound surgery.

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Topological crystallography of gas hydrates

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273315008864 ◽

2015 ◽

Vol 71 (4) ◽

pp. 444-450 ◽

Cited By ~ 2

Author(s):

Sergey V. Gudkovskikh ◽

Mikhail V. Kirov

Keyword(s):

Hydrogen Bonding ◽

Gas Hydrates ◽

Periodic Boundary ◽

Periodic Boundary Conditions ◽

Hexagonal Structure ◽

New Approach ◽

Quotient Graphs ◽

Disordered Structure ◽

Unit Cells ◽

Cubic Structure

A new approach to the investigation of the proton-disordered structure of clathrate hydrates is presented. This approach is based on topological crystallography. The quotient graphs were built for the unit cells of the cubic structure I and the hexagonal structure H. This is a very convenient way to represent the topology of a hydrogen-bonding network under periodic boundary conditions. The exact proton configuration statistics for the unit cells of structure I and structure H were obtained using the quotient graphs. In addition, the statistical analysis of the proton transfer along hydrogen-bonded chains was carried out.

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Image Simulations of Ge Twin Boundaries.

MRS Proceedings ◽

10.1557/proc-295-173 ◽

1992 ◽

Vol 295 ◽

Cited By ~ 1

Author(s):

Stuart Mckernan ◽

C. Barry Carter

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

High Angle ◽

Structural Units ◽

Twin Boundaries ◽

Large Unit ◽

Unit Cells ◽

The Individual ◽

Image Simulations

AbstractGeneral high-angle tilt grain boundaries may be described by an arrangement of repeating structural units. Some grain-boundary defects may also be modeled by the incorporation of structural units of related boundary structures into the boundary. The simulation of these structures requires the use of prohibitively large unit cells. The possibility of modeling these boundaries by the superposition of image simulations of the individual structural units isinvestigated.

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DESIGN, SYNTHESIS AND ANTICONVULSANT PROFILE OF 5-(BENZO [D][1,3]DIOXOL-5-YL)-3-TERT-BUTYL-4, 5-DIHYDROPYRAZOLE DERIVATIVES

International Journal of Pharmacy and Pharmaceutical Sciences ◽

10.22159/ijpps.2017v9i6.17520 ◽

2017 ◽

Vol 9 (6) ◽

pp. 180

Author(s):

Mohammed Farrag El-behairy ◽

Hanan Naeim Hafez Attia

Keyword(s):

Wide Spectrum ◽

Biological Evaluation ◽

Synthetic Methods ◽

Molecular Hybridization ◽

Lead Compound ◽

Design Synthesis ◽

Reference Drug ◽

Spectral Techniques ◽

Tert Butyl ◽

In Series

Objective: Utilisation of the ligand-based design and molecular hybridization to design promising candidates with prospective efficacy and safety. Synthesis of the designed candidates using different synthetic methods. Biological evaluation of the newly synthesised candidates as anticonvulsant agents.Methods: Three novel series of 5-(benzo[d][1,3]dioxol-5-yl)-3-tert-butyl-4,5-dihydropyrazoles have been designed via ligand-based drug discovery and molecular hybridization. Proper synthetic routes have been followed in the preparation of compounds (2-23) which have been characterised by different spectral techniques. Antiepileptic potential was assessed by biological evaluation using ‘classical’ animal models of epilepsy, in addition to rotarod test for toxicity.Results: 4-Nitrophenyl derivatives (5, 13, and19) displayed the highest potency. Compound 5was the most active substituent in series A (N'-aroyl-3-tert-butyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide). It was 2.7 and 1.3 times more active than reference drug Stiripentol (I) and lead compound III, respectively. Compound13 was the best candidate in series B (N'-arylidene-3-tert-butyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide). It was 3.3, 1.5, and 1.2 times more potent than Stiripentol, lead compound III and new compound 5, respectively. Two members (19 and 21) of series C (1,3,4-oxadiazole derivatives) achieved 100 % protection at lower doses than I and III, being 2.6 and 2.4 times more active than Stiripentol. In scPTZ screen, the most active congeners (5, 13, 19) exhibited ED50 values of 45, 48, and 81 mg/kg, respectively, which are highly superior as compared to that of reference drug Stiripentol(I) and lead compound III (ED50 115 and 110 mg/kg, respectively).Conclusion: Ligand-based design together with molecular hybridization in drug design succeeded to produce potent and wide spectrum candidates.

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Fundamental Property of Metals – Grain Boundaries Phase Transition as a Basis of Nanostructured Layers, Materials and Composites Production

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1852 ◽

2010 ◽

Vol 654-656 ◽

pp. 1852-1855 ◽

Cited By ~ 3

Author(s):

Y.A. Minaev

Keyword(s):

Phase Transition ◽

Grain Boundaries ◽

Fundamental Property ◽

Hard Metal ◽

Surface Layers ◽

Crystalline Materials ◽

First Order Phase Transition ◽

Hard Metals ◽

Nanostructured Layers ◽

First Order Phase

The obtained generalized equation for description of a fundamental property of solid crystalline materials i.e. first-order phase transition of the grain boundaries with formation of two-dimensional liquid has been used for calculating of transition temperature of any metals, which value lies in range 0.55 – 086 of melting point. Based on these conclusions to develop strategies for effective forming of coatings by synthesis of nitrides and carbonitrides on surface layers of hard metals and chromium steels have been made. It was shown the hardening of thin surface layer (0.1-0.5mm) due enriched of a nitrides in steels and carbonitrides with diamond like structure and strengthening the following layer by recristallization of W carbides in WC-Co and WC-TiC-Co hard metal. These result to increase of alloys hardness, ductility, and resistance to wear and decrease of sensibility to fragile rupture. Industrial tests have been made.

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Effect of Aluminum Concentration And Boron Dopant on Environmental Embriitlement In Feal Aluminides

MRS Proceedings ◽

10.1557/proc-213-527 ◽

1990 ◽

Vol 213 ◽

Cited By ~ 15

Author(s):

C. T. Liu ◽

E. P. George

Keyword(s):

Aluminum Alloys ◽

Grain Boundaries ◽

Aluminum Concentration ◽

Al Alloy ◽

Test Environment ◽

Environmental Embrittlement ◽

Boron Doped ◽

Weak Boundaries ◽

Boron Dopant ◽

Strong Segregation

ABSTRACTThe room-temperature tensile properties of FeAl aluminides were determined as functionsof aluminum concentration (35 to 43 at. % Al), test environment, and surface (oil) coating. The two lower aluminum alloys containing 35 and 36.5% Al are prone to severe environmental embrittlement, while the two higher aluminum alloys with 40 and 43% Al are much less sensitive to change in test environment and surface coating. The reason for the different behavior is that the grain boundaries are intrinsically weak in the higher aluminum alloys, and these weak boundaries dominate the low ductility and brittle fracture behavior of the 40 and 43% Al alloys. When boron is added to the 40% Al alloy as a grain-boundary strengthener, the environmental effect becomes prominent. In this case, the tensile ductility of the boron-doped alloy, just like that of the lower aluminum alloys, can be dramatically improved by control of test environment (e.g. dry oxygen vs air). Strong segregation of boron to the grain boundaries, with a segregation factor of 43, was revealed by Auger analyses.

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