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Okner R.,Hebrew University of Jerusalem | Favaro G.,CSM Instruments SA | Radko A.,Hebrew University of Jerusalem | Domb A.J.,Hebrew University of Jerusalem | Mandler D.,Hebrew University of Jerusalem
Physical Chemistry Chemical Physics | Year: 2010

The electrochemically assisted codeposition of sol-gel thin films on stainless steel is described. Specifically, electrodeposition of films based on aminopropyltriethoxysilane (APTS), and its codeposition with propyltrimethoxysilane (PrTMOS) and phenyltrimethoxysilane (PhTMOS) has been accomplished by applying negative potentials. The latter increases the concentration of hydroxyl ions on the stainless steel surface and thus catalyzes the condensation and deposition of the sol-gel films. The films were characterized by profilometry, electrochemical impedance spectroscopy (EIS), alternating current voltammetry (ACV), goniometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM and SEM analysis of codeposited APTSPrTMOS films disclosed the structural changes induced by altering the deposition solution composition and the applied potential. Codeposited APTSPhTMOS did not show any structural differences from their electrodeposited homopolymers, while Nano Scratch Test clearly revealed the changes in the elastic and adhesion properties, suggesting the formation of an APTSPhTMOS composite. EIS of the films showed good resistance towards penetration of hydrophilic species, such as hexacyanoferrate. ACV measurements of the homo and codeposits showed the decrease of the interfacial capacity as a result of the electrochemical deposition. In essence, controllable sol-gel films with tunable chemical and physical properties based on controlling the combination of the precursors, pH and electrochemical properties can be electrodeposited on conducting surfaces. The application of this approach has been demonstrated by coating a stainless steel coronary stent. © 2010 the Owner Societies.

Ginzburg-Turgeman R.,Hebrew University of Jerusalem | Guion J.-B.,CSM Instruments SA | Mandler D.,Hebrew University of Jerusalem
Journal of Solid State Electrochemistry | Year: 2011

Indium tin oxide (ITO) is the most commonly used transparent conducting substance. It has been used in numerous applications such as light-emitting diodes. In most applications and studies, the ITO surface is further coated with additional layers. The interface between the ITO and the coating is of utmost importance since it affects the physical and chemical properties of the final device. Improving the adhesion between ITO and a coating layer can be achieved by applying a "molecular adhesive" as an inter-phasing molecular layer. In this study, we used 3-(trimethoxysilyl)propyl methacrylate as a "molecule adhesive" for better connection between ITO and a polymethacrylate layer. The samples were studied by electrochemistry, contact angle goniometry, atomic force microscopy, and nano scratch microscopy. These studies clearly show that a simple silanization process formed a thin molecular adhesive layer, which did not influence the physical and chemical properties of the final coated electrode and at the same time increased significantly the adhesion between the ITO and the polymethacrylate coating. © Springer-Verlag 2011.

Topic M.,Research Accelerator | Favaro G.,CSM Instruments SA | Bucher R.,Research Accelerator
Surface and Coatings Technology | Year: 2011

The effects of annealing on coating morphology and scratch resistance have been studied in several single and multilayered Pt-V coated systems. The changes in coating morphology included the formation of distinctive "square shape precipitates", increased surface roughness, coating thickening and cracking. The results show that scratch resistance was affected by coating thickness, the sequence of deposited layers and Pt-V phases induced by annealing. The scratch resistance was improved for all coated systems by annealing. However, there is an indication that a large volume fraction of PtV 3 formed at 900°C/45min significantly increased the critical load at which the coating failed. This result will be the base for further study on the development of targeted phases to improve the surface characteristics for specific coating applications. © 2011.

Nohava J.,CSM Instruments SA | Bonferroni B.,University of Modena and Reggio Emilia | Bolelli G.,University of Modena and Reggio Emilia | Lusvarghi L.,University of Modena and Reggio Emilia
Surface and Coatings Technology | Year: 2010

In order to improve the knowledge on the use and significance of instrumented indentation and scratch testing on thermally-sprayed materials, a wide range of tests was performed on thermally-sprayed ceramic, cermet and metal coatings. A scale-dependent behavior of hardness was observed as a function of indentation depth for all coatings: at low penetration depths, the hardness value depends on the intralamellar material properties, whereas at larger depths it reflects the long-range cohesive strength of the coating. In all cases, hardness becomes independent of the indentation depth above a threshold value of ~. 2000. nm. The elastic modulus is also scale-dependent, but it never stabilizes to a depth-independent value, probably on account of crack opening/closing mechanisms. Scratch test on the cross-section has been deeply investigated and identified as a comparative method to quantify the cohesion of the coatings. © 2010 Elsevier B.V.

Vilemova M.,Czech Institute of Plasma Physics | Matejicek J.,Czech Institute of Plasma Physics | Musalek R.,Czech Institute of Plasma Physics | Nohava J.,CSM Instruments SA
Journal of Thermal Spray Technology | Year: 2012

Mechanical and thermal properties of thermal sprayed coatings, especially ceramics, are strongly influenced by cracks and pores that are present in the coating microstructure. In the recent past, there have been efforts to find an analytical model describing the coating properties based on the microstructural characteristics. Various analytical models were developed and published in the literature. In this study, several major models were applied to ceramic and metal coatings to describe their elastic modulus and thermal conductivity. The sensitivity of the models to the variations in the microstructure and relevancy of their use in specific cases were examined. The results were compared with those obtained by FEM modeling and experimentally measured values. © ASM International.

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