Influence of deposition conditions on electrical and mechanical properties of Sm2O3 doped CeO2 thin films prepared by EB-PVD (+IBAD) methods part 2. Indentation hardness and effective elastic modulus

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

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Structural and Mechanical Properties of Nanostructured C-Ag Thin Films Synthesized by Thermionic Vacuum Arc Method

Journal of Nanomaterials ◽

10.1155/2018/9632041 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Rodica Vladoiu ◽

Aurelia Mandes ◽

Virginia Dinca-Balan ◽

Vilma Bursikova

Keyword(s):

Electron Microscopy ◽

Thin Films ◽

Mechanical Properties ◽

Elastic Modulus ◽

Silicon Substrate ◽

Vacuum Arc ◽

Average Roughness ◽

Thermionic Vacuum Arc ◽

Induced Aggregation ◽

Ag Film

Nanostructured C-Ag thin films of 200 nm thickness were successfully synthesized by the Thermionic Vacuum Arc (TVA) method. The influence of different substrates (glass, silicon wafers, and stainless steel) on the microstructure, morphology, and mechanical properties of nanostructured C-Ag thin films was characterized by High-Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and TI 950 (Hysitron) nanoindenter equipped with Berkovich indenter, respectively. The film’s hardness deposited on glass (HC-Ag/Gl = 1.8 GPa) was slightly lower than in the case of the C-Ag film deposited on a silicon substrate (HC-Ag/Si = 2.2 GPa). Also the apparent elastic modulus Eeff was lower for C-Ag/Gl sample (Eeff = 100 GPa) than for C-Ag/Si (Eeff = 170 GPa), while the values for average roughness are Ra=2.9 nm (C-Ag/Si) and Ra=10.6 (C-Ag/Gl). Using the modulus mapping mode, spontaneous and indentation-induced aggregation of the silver nanoparticles was observed for both C-Ag/Gl and C-Ag/Si samples. The nanocomposite C-Ag film exhibited not only higher hardness and effective elastic modulus, but also a higher fracture resistance toughness to the silicon substrate compared to the glass substrate.

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A Method to Determine Fracture Toughness Using Berkovich Indenter for Bulk Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.331.456 ◽

2013 ◽

Vol 331 ◽

pp. 456-460

Author(s):

Min He ◽

Duan Hu Shi ◽

Feng Yang ◽

Ning Zhang ◽

Hua Feng Guo

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Elastic Modulus ◽

Penetration Depth ◽

Effective Elastic Modulus ◽

Berkovich Indenter ◽

Bulk Materials ◽

Ductile Materials ◽

Penetration Depths ◽

Determine Fracture Toughness

An indentation approach with Berkovich indenter is proposed to determine fracture toughness for ductile materials. With decrease of effective elastic modulus, an approximate linear relationship between logarithmic plastic penetration depth and logarithmic effective elastic modulus, and a quadratic polynomial relationship between the plastic penetration depths and penetration loads are exhibited by indentation investigation with Berkovich indenter. The damage constructive equation of effective elastic modulus is proposed to determine the critical effective elastic modulus at the fracture point, which is the key problem to calculate the indentation energy to fracture. The critical plastic penetration depth is identified after the critical effective elastic modulus can be predicted by conventional mechanical properties. The fracture toughness is calculated according to the equation of penetration load, plastic penetration depth and the critical plastic penetration depth.

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Characterization of Nanoporous Low Dielectric Polysilsesquioxane Thin Films

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.277-279.907 ◽

2005 ◽

Vol 277-279 ◽

pp. 907-911

Author(s):

Jingyu Hyeon Lee ◽

Yi Yeol Lyu ◽

Mong Sup Lee ◽

Jin Heong Yim ◽

Sang Youl Kim

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Dielectric Constant ◽

Refractive Index ◽

Elastic Modulus ◽

Polymer Matrix ◽

Low Dielectric

Poly(methyl-co-cyclosiloxane bearing silsesquioxane)s (P(M-co-CSSQs)) were prepared. Using poly(e-caprolactone) (PCL) as a template, PCL / P(M-co-CSSQ) nanohybrid films were fabricated. The electrical, morphological, and mechanical properties of the PCL / P(M-co-CSSQ) films were investigated. The dielectric constant of a cured PCL / P(M-co-CSSQ) film at 420°C scaled down from 2.55 to 2.05 and refractive index from 1.41 to 1.33 when 20 vol. % of the PCL was admixed with the polymer matrix. The elastic modulus and hardness of the cured PCL / P(Mco- CSSQ) (2:8, vol./vol.) film were 2.50 and 0.32 GPa, respectively, showing dependency on the PCL content.

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Механизмы возникновения напряжений в тонких пленках и покрытиях

Журнал технической физики ◽

10.21883/jtf.2020.12.50112.38-20 ◽

2020 ◽

Vol 90 (12) ◽

pp. 1971

Author(s):

А.Р. Шугуров ◽

А.В. Панин

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Chemical Composition ◽

Phase Transformations ◽

Stress Generation ◽

Amorphous Films ◽

Misfit Stress ◽

Crystal Lattices ◽

Generation Mechanisms ◽

Deposition Conditions

The paper considers current conceptions of generation of mechanical stresses in epitaxial, polycrystalline and amorphous films during their growth and under different external actions. The mechanism of stress generation in geteroepitaxial films due to misfit in crystal lattices of the film and substrate is described. The relation between arising of the misfit stress in heterostructures and variation of their growth mode is shown. The mechanisms of generation of compressive and tensile stresses in polycrystalline films caused by nucleation and coalescence of islands at the beginning of their growth are considered. Different aspects of evolution of intrinsic stresses in continuous films are discussed in dependence of their deposition conditions, chemical composition, microstructure and mechanical properties. Special attention is given to consideration of generation mechanisms of intrinsic stresses in thin films concerned with formation of pint defects, incorporation of impurities and phase transformations during deposition. Factors leading to arising extrinsic stresses in thin films during their storage and operation are described in details.

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Study on the Influence of the Grind Percentage Over the Surface Hardness and Modulus of Elasticity of Parts Made of ABS, P6.6 and POM through Nanoindentation

Materiale Plastice ◽

10.37358/mp.19.1.5124 ◽

2019 ◽

Vol 56 (1) ◽

pp. 65-70

Author(s):

Gheorghe Radu Emil Maries ◽

Constantin Bungau ◽

Dan Chira ◽

Traian Costea ◽

Danut-Eugeniu Mosteanu

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Surface Hardness ◽

Acrylonitrile Butadiene Styrene ◽

The Other ◽

Indentation Hardness ◽

Indentation Modulus ◽

Maximum Hardness ◽

New Material ◽

Butadiene Styrene

This paper analyzes the indentation hardness and the indentation elastic modulus variation depending on the variation of the grind percentage of polymer, when the other factors that can influence the injection molding remain unchanged. The analyzed polymers were: acrylonitrile butadiene styrene ABS MAGNUM 3453, polyamide PA 6.6 TECHNYL AR218V30 Blak and polyoxymethylene POM EUROTAL C9 NAT. The samples that were studied had different compositions in new and grinding material. The G-Series Basic Hardness Modulus at a Depth method was used. The increase of the grind percentage of ABS (from 0 to 100 %) leads to insignificant changes in the indentation hardness, indentation modulus, and maximum force applied to samples of tested material. The maximum hardness (0.137 GPa) of PA 6.6 is recorded in the case of the sample with 80% grind content, and the maximum hardness of POM is recorded as well in the case of the sample with 80% grind content, as being 0.215 GPa. The variation of the grind content in the analyzed samples determines changes in the evaluated parameters, depending on the type of polymer. Combining the new material with grind in proportions experimentally established for each techno polymer leads to changes in their mechanical properties.

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A Direct Comparison of Three Buckling-Based Methods to Measure the Elastic Modulus of Nanobiocomposite Thin Films

10.26434/chemrxiv.12746579 ◽

2020 ◽

Author(s):

Taylor C. Stimpson ◽

Daniel A. Osorio ◽

Emily D. Cranston ◽

Jose Moran-Mirabal

Keyword(s):

Thin Film ◽

Thin Films ◽

Mechanical Properties ◽

Elastic Modulus ◽

Elastic Moduli ◽

Input Parameter ◽

Layer By Layer ◽

Free Standing ◽

Film Composition ◽

Parameter Values

<p>To engineer tunable thin film materials, accurate measurement of their mechanical properties is crucial. However, characterizing the elastic modulus with current methods is particularly challenging for sub-micrometer thick films and hygroscopic materials because they are highly sensitive to environmental conditions and most methods require free-standing films which are difficult to prepare. In this work, we directly compared three buckling-based methods to determine the elastic moduli of supported thin films: 1) biaxial thermal shrinking, 2) uniaxial thermal shrinking, and 3) the mechanically compressed, strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) method. Nanobiocomposite model films composed of cellulose nanocrystals (CNCs) and polyethyleneimine (PEI) were assembled using layer-by-layer deposition to control composition and thickness. The three buckling-based methods yielded the same trends and comparable values for the elastic moduli of each CNC-PEI film composition (ranging from 15 – 44 GPa, depending on film composition). This suggests that the methods are similarly effective for the quantification of thin film mechanical properties. Increasing the CNC content in the films statistically increased the modulus, however, increasing the PEI content did not lead to significant changes. The standard deviation of elastic moduli determined from SIEBIMM was 2-4 times larger than for thermal shrinking, likely due to extensive cracking and partial film delamination. In light of these results, biaxial thermal shrinking is recommended as the method of choice because it affords the simplest implementation and analysis and is the least sensitive to small deviations in the input parameter values, such as film thickness or substrate modulus.</p>

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Measuring the elastic modulus and residual stress of freestanding thin films using nanoindentation techniques

Journal of Materials Research ◽

10.1557/jmr.2009.0360 ◽

2009 ◽

Vol 24 (9) ◽

pp. 2974-2985 ◽

Cited By ~ 14

Author(s):

Erik G. Herbert ◽

Warren C. Oliver ◽

Maarten P. de Boer ◽

George M. Pharr

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Residual Stress ◽

Thermal Expansion ◽

Elastic Modulus ◽

Dimensional Analysis ◽

Experimental Verification ◽

Cu Films ◽

Proposed Model ◽

The Difference

A new method is proposed to determine the elastic modulus and residual stress of freestanding thin films based on nanoindentation techniques. The experimentally measured stiffness-displacement response is applied to a simple membrane model that assumes the film deformation is dominated by stretching as opposed to bending. Dimensional analysis is used to identify appropriate limitations of the proposed model. Experimental verification of the method is demonstrated for Al/0.5 wt% Cu films nominally 22 µm wide, 0.55 µm thick, and 150, 300, and 500 µm long. The estimated modulus for the four freestanding films match the value measured by electrostatic techniques to within 2%, and the residual stress to within 19.1%. The difference in residual stress can be completely accounted for by thermal expansion and a modest change in temperature of 3 °C. Numerous experimental pitfalls are identified and discussed. Collectively, these data and the technique used to generate them should help future investigators make more accurate and precise measurements of the mechanical properties of freestanding thin films using nanoindentation.

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