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

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.

1999 ◽  
Vol 574 ◽  
Author(s):  
Norifumi Fujimura ◽  
Tamaki Shimura ◽  
Toshifumi Wakano ◽  
Atsushi Ashida ◽  
Taichiro Ito

AbstractWe propose the application of ZnO:X (X = Li, Mg, N, In, Al, Mn, Gd, Yb etc.) films for a monolithic Optical Integrated Circuit (OIC). Since ZnO exhibits excellent piezoelectric effect and has also electro-optic and nonlinear optic effects and the thin films are easily obtained, it has been studied as one of the important thin film wave guide materials especially for an acoustooptic device[1]. In terms of electro-optic and nonlinear optic effects, however, LiNbO3 or LiTaO3 is superior to ZnO. The most important issue of thin film waveguide using such ferroelectrics is optical losses at the film/substrate interface and the film surface, because the process window to control the surface morphology is very narrow due to their high deposition temperature. Since ZnO can be grown at extremely low temperature, the roughness at the surface and the interface is expected to be minimized. This is the absolute requirement especially for waveguide using a blue or ultraviolet laser. Recently, lasing at the wavelength of ultraviolet, ferroelectric and antiferromagnetic behaviors of ZnO doped with various exotic elements (exotic doping) have been reported. This paper discusses the OIC application of ZnO thin films doped with exotic elements.


2013 ◽  
Vol 05 (02) ◽  
pp. 1350012 ◽  
Author(s):  
HONG-PING ZHAO ◽  
YECHENG WANG ◽  
BING-WEI LI ◽  
XI-QIAO FENG

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.


Author(s):  
W. Liu ◽  
Y. G. Wang ◽  
L. Li

It is a very important problem to obtain high critical current density Jc in high critical temperature Tc superconductors. For high Tc thin film superconductors, the Jc value can reach >106 A/cm2 at 77K. We have prepared YBa2Cu3Oy (YBCO) thin films by magnetron sputtering method, the Jc values ranged from 104 -106 A/cm2, the films were deposited both on (100) SrTiO3 and (100) LaAlO3 substrates. It is well known that Jc is closely related to the microstructure of the film, in this paper we report the observation by high resolution electron microscopy of the boundary between film and substrate and analysis the result with relation to the Jc values of the films.The cross sectional specimens of the film and substrate boundary were prepared by cutting the film-substrate sample into thin slices, then stick the slices with film surface face to face by epoxy resin.


2011 ◽  
Vol 121-126 ◽  
pp. 4295-4299
Author(s):  
Hao MA Yun ◽  
Lu Ping Chao ◽  
J. S Hsu

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.


2006 ◽  
Vol 976 ◽  
Author(s):  
Yun-Hee Lee ◽  
Yong-Il Kim ◽  
Hoon-Sik Jang ◽  
Seung-Hoon Nahm ◽  
Ju-Young Kim ◽  
...  

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.


2006 ◽  
Vol 315-316 ◽  
pp. 766-769
Author(s):  
Yong Zhi Cao ◽  
Ying Chun Liang ◽  
Shen Dong ◽  
T. Sun ◽  
Bo Wang

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.


2013 ◽  
Vol 470 ◽  
pp. 521-524
Author(s):  
Ban Quan Yang ◽  
Jun Du ◽  
Xue Jun Chen ◽  
Wei Hai Sun ◽  
Hong Qian Chen ◽  
...  

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.


Author(s):  
A. Hossain ◽  
A. Mian

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.


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