Papers by Keyword: Adhesion

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Authors: Yusuke Ushiro, Daisuke Okai, Atsushi Yamamoto
Abstract: The fracture behavior and adhesion strength of CrN/Cr and CrN films on SKD61 substrates were investigated by a three-point bending test. The SKD61 substrates were coated with a film with multilayer of CrN/Cr and a single film of CrN by a physical vapor deposition (PVD). The fracture behaviors of CrN/Cr and CrN films at three-point bending test were observed by scanning electron microscopy (SEM). Adhesions of the CrN/Cr/SKD61 and the CrN/SKD61 were also evaluated using a scratch tester. The scratch test resulted in no great difference in the adhesion strength between the CrN/Cr/SKD61 and the CrN/SKD61. On the other hand, the three-point bending test showed a high adhesion of the CrN/Cr with the intermediate layer of Cr film compared to the CrN on the SKD61.
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Authors: Agnese Pavlova, Aigars Reinis, Liga Berzina-Cimdina, Juta Kroica, Aleksandra Burlakova, Kristaps Rubenis
Abstract: Extrusion is a perspective forming technology for obtaining objects with certain profile, important for the TiO2 application as biomaterial. Extruded samples were calcinated at 1100 °C, thermally treated in different atmospheres: at 1450 °C in air and at 1300 °C in vacuum. An approach was made to examine the adhesion and colonization intensity of Staphylococcus epidermidis and Pseudomonas aeruginosa on TiO2 ceramic in vitro. It was found that Ps.aeruginosa demonstrated higher adhesion and colonization intensity as S.epidermidis and TiO2 samples treated in vacuum demonstrated higher attachment of microorganisms as TiO2 samples treated in air. It was supposed that surface charge promoted the bacterial adhesion on the vacuum treated samples.
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Authors: Gigliola Lusvardi, Ginaluca Malavasi, Ledi Menabue, Maria Cristina Menziani
Abstract: This review presents a combined experimental-computational strategy for the development of potential bioactive zinc–containing silicate glasses and shows how sound relationships among the structural role of some key elements that appear to control bioactivity can by established and exploit for rational glass design.
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Authors: Gang Sun, Yan Fang
Abstract: The microstructure, hydrophobicity and chemical composition of the butterfly and locust wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter and a Fourier transform infrared spectrometer (FT-IR). The hydrophobicity models were established on the basis of the Cassie equation. The wetting mechanism was comparatively discussed from the perspective of biological coupling. The butterfly and the locust wing surfaces are composed of naturally hydrophobic materials, but exhibit different complex wettability. The butterfly wing surface is of low adhesion (sliding angle 1~3°) and superhydrophobicity (contact angle 151.6~156.9°), while the locust wing surface is of extremely high adhesion (sliding angle>180°) and superhydrophobicity (contact angle 155.8~157.3°). The complex wettability of the wing surfaces ascribes to the coupling effect of hydrophobic material and rough structure. The butterfly and locust wings can be used as bio-templates for design and preparation of biomimetic functional surface, intelligent interfacial material and no-loss microfluidic transport channels.
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Authors: N. Donnelly, M. McConnell, Denis P. Dowling, J.D. O'Mahony
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Authors: Gang Sun, Yan Fang
Abstract: The microstructure, hydrophobicity and chemical composition of the locust and moth wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter and a Fourier transform infrared spectrometer (FT-IR). The hydrophobicity models were established on the basis of the Cassie-Baxter equation. The locust and moth wing surfaces are composed of naturally hydrophobic materials, but exhibit different complex wettability. The locust wing surface is of extremely high adhesion (sliding angle>180°) and superhydrophobicity (contact angle 151.5~157.3°), while the moth wing surface is of low adhesion (sliding angle 1~3°) and superhydrophobicity (contact angle 150.5~155.6°). The complex wettability of the wing surfaces ascribes to the cooperative effect of material element and structural element. The locust and moth wings can be potentially used as biomimetic templates for design and preparation of novel functional interface and no-loss microfluidic transport channels.
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Authors: Jun Zhang, Zhong Yao Zhao, Xin Li Wei
Abstract: A modified cohesive zone interface model that has a damage factor couple with the thermal cycle and humidity aging was proposed. The damage factor not only can change the cohesive zone strength acting but also can effect on the energies of separation. The modified cohesive zone interfacial model is developed and implemented in ABAQUS, as a user element subroutine, to simulate the peeling process for the specimen bonding by anisotropic conducive adhesive film (ACF) under the thermal cycle and humidity tests. Finite element explicit code and the constitutive relation of this element has been defined by the user-defined mechanical material behaviour (VUMAT). The bulk material element selected is a 4-node bilinear plane stress quadrilateral element, and the reduced integration and hourglass control are also adopted. The numerical simulated results accorded well to the experiments to illustrate the validity of the new model.
374
Authors: Sharon Kao-Walter, Per Ståhle, Shao Hua Chen
Abstract: The crack tip driving force of a crack growing from a pre-crack that is perpendicular to and terminating at an interface between two materials is investigated using a linear fracture mechanics theory. The analysis is performed both for a crack penetrating the interface, growing straight ahead, and for a crack deflecting into the interface. The results from finite element calculations are compared with asymptotic solutions for infinitesimally small crack extensions. The solution is found to be accurate even for fairly large amounts of crack growth. Further, by comparing the crack tip driving force of the deflected crack with that of the penetrating crack, it is shown how to control the path of the crack by choosing the adhesion of the interface relative to the material toughness.
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Authors: Kang Qi Fan, Chun Hui Xu, Feng Bo Chao
Abstract: There have been increasing research interests in the measurement of the mechanical properties of nanoscale materials by pressing a spherical tip into surfaces of the tested materials. To acquire a better understanding of this process, a model of adhesive contact between a spherical tip and a flat surface is developed by employing the Hamaker hypotheses and molecular dynamics (MD) method. With this model, the deformation characteristics of the tested surface are illustrated by the key snapshots of the deformed surface and the corresponding curves of pressure distribution. The results indicate that the contact can be formed before the tip impresses into the surface. Moreover, the variation of the adhesive force with the distance is recorded during the approach and separation processes, and the adhesion hysteresis is demonstrated by the force-distance curve. Additionally, the stepwise increase of the contact radius with a decrease in the distance is revealed and investigated.
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