IMPROVEMENT OF THE PEELING STRENGTH OF THIN FILMS BY A BIOINSPIRED HIERARCHICAL INTERFACE

2013 ◽  
Vol 05 (02) ◽  
pp. 1350012 ◽  
Author(s):  
HONG-PING ZHAO ◽  
YECHENG WANG ◽  
BING-WEI LI ◽  
XI-QIAO FENG
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Interface Model ◽  
Cohesive Interface ◽  
Flat Interface ◽  
Peeling Strength ◽  
Wavy Interface ◽  
Sinusoidal Shape ◽  
Film Substrate ◽  
Curved Interface

The peeling behavior of a thin film bonded to a substrate is investigated by using the cohesive interface model. We compare the peeling processes of film/substrate interfaces with three different geometric shapes, including a flat interface, a curved interface of sinusoidal shape, and a wavy interface with two-level sinusoidal hierarchy. The effect of the peeling angle on the maximal peeling strength is also examined. It is demonstrated that the peeling strength can be significantly improved by introducing a hierarchical wavy morphology at the film/substrate interface. This study may be helpful for the design of film/substrate systems with enhanced mechanical properties.

Appling of New Optical Measurement and Theory in Mechanical Properties of Thin Film

2011 ◽  
Vol 121-126 ◽  
pp. 4295-4299
Author(s):  
Hao MA Yun ◽  
Lu Ping Chao ◽  
J. S Hsu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Thermal Stresses ◽  
Optical Measurement ◽  
Phase Shifting ◽  
Deposition Condition ◽  
Full Field ◽  
Evaporation Technique ◽  
Film Substrate

The thesis aims to characterize the mechanical properties and stresses for thin films deposited on the circular substrates. First, the thin films with the same deposition condition were successively deposited on the distinct substrates using the evaporation technique. The phase-shifting Twyman-Green interferometer (PSTGI) was then employed to measure the warpage of the film-substrate structures and therefore the intrinsic stresses and thermal stresses can be calculated from the well-known Stoney’s formula. The coefficients of thermal expansion (CTE) and Young’s modulus of thin films were also obtained from the Stoney’s theory. Furthermore, the merit of full-field character of optical interferometry was used to propose a novel methodology using the Chen and Ou’s theory to improve the accuracy and to reduce the experiment procedures in the traditional measurement of the aforementioned mechanical properties. Finally, the measured results corresponding to the traditional and proposed methods were respectively substituted into their adopted theories to compare their difference. The results reveal that the accuracy of proposed methodology is considerably improved and the experimental procedures are reduced to those of the traditional methods.

On the Characterization of Thin Film-only Mechanical Property Based on the Indentation Image Analysis

2006 ◽  
Vol 976 ◽  
Author(s):  
Yun-Hee Lee ◽  
Yong-Il Kim ◽  
Hoon-Sik Jang ◽  
Seung-Hoon Nahm ◽  
Ju-Young Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Penetration Depth ◽  
Volume Ratio ◽  
Hardness Measurement ◽  
Relative Depth ◽  
Au Thin Films ◽  
Film Substrate ◽  
Indenter Penetration

AbstractConventional nanoindentation testing generally uses a peak penetration depth of less than 10 % of thin-film thickness in order to measure film-only mechanical properties, without considering the critical depth for a given thin film-substrate system. The uncertainties in this testing condition make hardness measurement more difficult. We propose a new way to determine the critical relative depth for general thin-film/substrate systems; an impression volume analyzed from the remnant indent image is used here as a new parameter. Nanoindents made on soft Cu and Au thin films with various indentation loads were observed by atomic force microscope. The impression volume calculated from 3D remnant image was normalized by the indenter penetration volume. This indent volume ratio varied only slightly in the shallow regime but decreased significantly when the indenter penetration depth exceeded the targeted critical relative depth. Thus, we determined the critical relative depth by empirically fitting the trend of the indent volume ratio and determining the inflection point. The critical relative depths for Cu and Au films were determined as 0.170 and 0.173, respectively, values smaller than 0.249 and 0.183 determined from the hardness variation of the two thin films. Hence the proposed indent volume ratio is highly sensitive to the substrate constraint, and stricter control of the penetration depth is needed to measure film-only mechanical properties.

Effects of the Substrate on the Determination of SEBS Thin Film Mechanical Properties by Nanoindentation

2006 ◽  
Vol 315-316 ◽  
pp. 766-769
Author(s):  
Yong Zhi Cao ◽  
Ying Chun Liang ◽  
Shen Dong ◽  
T. Sun ◽  
Bo Wang
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Polymer Film ◽  
Young’S Modulus ◽  
Penetration Depth ◽  
Young's Modulus ◽  
Polymer Film Substrate ◽  
Film Substrate ◽  
Composite Hardness

In order to investigate nanoindentation data of polymer film-substrate systems and to learn more about the mechanical properties of polymer film-substrate systems, SEBS (styreneethylene/ butylene-styrene) triblock copolymer thin film on different substrate systems have been tested with a systematic variation in penetration depth and substrate characteristics. Nanoindentation experiments were performed using a Hysitron TriboIndenter with a Berkvoich tip. The resulting data were analyzed in terms of load-displacement curves and various comparative parameters, such as hardness and Young’s modulus. The results obtained by the Oliver and Pharr method show how the composite hardness and Young’s modulus are different for different substrates and different penetration depth.

Effect of the Mechanical Properties and Geometric Parameters on the Crack Density of the Thin Film/Substrate System under Residual Stress and Uniaxial Tensile Loading

2013 ◽  
Vol 470 ◽  
pp. 521-524
Author(s):  
Ban Quan Yang ◽  
Jun Du ◽  
Xue Jun Chen ◽  
Wei Hai Sun ◽  
Hong Qian Chen ◽  
...  
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Crack Density ◽  
Tensile Loading ◽  
Interface Layer ◽  
Geometric Parameters ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Loading ◽  
Film Substrate

The effect of the mechanical properties and geometric parameters on the crack density of the thin film/substrate system under residual stress and uniaxial tensile loading is investigated in this work. The numerical results show that the crack density of the thin film increases with the increase of the Youngs modulus of the thin film and (or) the shear modules of the interface layer, and it decreases with the increase of the thickness of the thin film and (or) the fracture strength of the thin film. These results can help us more deeply understand the fracture behavior of the brittle thin film on the substrate under residual stress and external tensile loading.

Factors Affecting Spherical Nano-Indentation of Thin Film/Substrate Systems

2014 ◽  
Author(s):  
A. Hossain ◽  
A. Mian
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Indentation Test ◽  
Element Analysis ◽  
Factors Affecting ◽  
Nano Indentation ◽  
Fea Modeling ◽  
Soft Biological Materials ◽  
Film Substrate

Great interests have been made over the last few years in the development of techniques to measure the mechanical properties of many engineering materials at the nano scale. In nano-indentation, a hard tip with known mechanical properties is pressed into a sample whose properties are unknown. The load, indentation depth and deformed area resulting from this test are then used to determine the desired mechanical properties, such as hardness and modulus. In this study, the computer-based finite element analysis (FEA) method is used to investigate factors effecting nano-indentation to ensure reliable measurement of thin film properties. First, the FEA method is used to predict the mechanical response of bulk aluminum (Al) using a spherical indenter. The numerical prediction is then compared with existing published results to validate the FEA modeling scheme. Once the model is validated, additional numerical analyses are conducted to investigate the response of Al-film deposited on different substrate materials. New mathematical formulations are proposed to determine the film modulus from nano-indentation test. The film modulus obtained from the new and existing mathematical formulations are also compared. Results obtained from this research can be used to characterize the mechanical properties of soft biological materials such as biofilm or tissue scaffolds.

Instability Analysis of Strained Interfaces Via a Discrete Atom Method

1994 ◽  
Vol 356 ◽  
Author(s):  
Jong K. Lee
Keyword(s):  
Thin Film ◽  
Morphological Evolution ◽  
Equilibrium Shape ◽  
Morphological Instability ◽  
Interfacial Waves ◽  
Substrate Interface ◽  
Film Substrate ◽  
The Waves ◽  
Curved Interface ◽  
Dimensional Crystal

AbstractThe morphological instability of an epitaxially-strained, thin film is studied by means of a discrete atom method in a dislocation-free, two-dimensional crystal. The instability of the film-substrate interface is also examined in conjunction with the migration of the free surface. The results show that a mobile film-substrate interface can accelerate merger between the two surfaces, and anisotropic effects facilitate island formation. In addition, the instability of a curved interface is discussed with the results on the morphological evolution of coherent precipitates. A circular, soft precipitate in an isotropic matrix undergoes a series of shape transitions before reaching its equilibrium shape. As in the strained thin film case, transition begins with interfacial waves induced by the coherency strain. The waves then develop small lobes, which coarsen into a lower density of larger lobes. The larger lobes eventually coarsen as the equilibrium shape is approached. Anisotropic effects suppress some of the interfacial waves.

Correlation between Adhesion Strength and Thin film/Substrate Mechanical Properties using the Nano-Scratch Technique

2011 ◽  
Vol 1297 ◽  
Author(s):  
Bo Zhou ◽  
Nicholas Randall ◽  
Barton Prorok
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Adhesion Strength ◽  
Film Surface ◽  
Scratch Testing ◽  
Coating Failure ◽  
Failure Loads ◽  
Load Mode ◽  
Film Substrate ◽  
Scratch Tests

ABSTRACTScratch testing, as a mature technique for coating adhesion quantification, has been widely adopted by both industrial and academic fields in recent years. Following the urgent needs of very small materials characterization, nano-scratch testing has gradually replaced the traditional pull-off test for the study of ultra-thin film properties. In this research, the relationship between the adhesion strength and film/substrate mechanical properties was investigated to provide fundamental but crucial knowledge of the scratch mechanism. Scratch tests were performed on different film/substrate combinations using a Nano Scratch Tester with a sphero-conical diamond indenter. A progressive load mode was employed to cause coating failure during scratch on the film surface. The critical values of different failure mechanisms, such as cracking and delamination were accurately determined according to the scratch panorama image, penetration and residual depth data. In addition, the hardness (H) and modulus (E) values of the thin films and substrates were measured with an Ultra Nanoindentation Tester. The scratch critical failure loads were then plotted versus film/substrate H and E ratios. A unique relationship was found between these parameters that could help understand the true mechanism behind scratch adhesion and leverage this methodology to a new theoretical level.

Thermo-Mechanical Ni50Ti50/Si Composite Thin Film Switch

1994 ◽  
Vol 360 ◽  
Author(s):  
T. Kim ◽  
Quanmin Su ◽  
Manfred Wuttig
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Composite Thin Film ◽  
Substrate Stiffness ◽  
Substrate Thickness ◽  
Substantial Influence ◽  
Mechanical Constraints ◽  
Switch Type ◽  
Film Substrate ◽  
Type Composite

AbstractThe mechanical properties of Ni50Ti50 deposited on Si and 3C-SiC substrates were studied focussing on the interaction of the film and substrate. This interaction determines the transformation characteristics through interface accommodation and mechanical constraints exerted by the substrate stiffness. Substrate stiffness, controlled by the film/substrate thickness ratio, was found to have a substantial influence on the output energy of the film/substrate composite. A switch type composite based on this knowledge was fabricated and tested.

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