Agency: European Commission | Branch: FP7 | Program: CSA-CA | Phase: NMP-2007-2.1-3 | Award Amount: 717.21K | Year: 2008
Our project aims to gather, improve, catalogue and present characterisation techniques, methods and equipment for nanomechanical testing. European-wide activities coordinated by a new virtual centre will improve existing nanoindentation metrology to reveal structure-properties relationship at the nano-scale. These methods are the only tools to characterise nanocomposite, nanolayer and interface mechanical behaviours in the nanometre range. This work will also lay down a solid base for subsequent efforts for defining and preparing new standards to support measurement technology in the field of nanomaterials characterisation. Steps include development of the classical and the dynamic nanoindentation method and its application to new fields, application of modified nano-indenters to new fields as scratching and wear measurement, firm and uniform determination of instrumental parameters and defining new standard samples for the new applications. The virtual centre will disseminate information based on a new Nanocharacterisation database built on two definite levels: on a broader level partners will inventory and process all novel nanocharacterisation techniques and, in narrower terms, they will concentrate on nanomechanical characterisation. This will be achieved through the synchronisation of efforts set around a core of round robins but the database will include data of other channels as parallel research work and literature recherch. Core activities comprise detailed dissemination activities. Indirect connections to the stakeholders by a webpage with a build-in interactive database will be complemented by direct events such as participation in workshops (oral and poster presentations), and regular technical reports in international journals. Activities above will lead to detailed descriptions of novel characterisation techniques. The development and definition of new standards and good practices will support design of intrinsically safe nanomaterials for wide industrial applications.
Guldin S.,University of Cambridge |
Guldin S.,Ecole Polytechnique Federale de Lausanne |
Kohn P.,University of Cambridge |
Stefik M.,University of South Carolina |
And 6 more authors.
Nano Letters | Year: 2013
Low-cost antireflection coatings (ARCs) on large optical surfaces are an ingredient-technology for high-performance solar cells. While nanoporous thin films that meet the zero-reflectance conditions on transparent substrates can be cheaply manufactured, their suitability for outdoor applications is limited by the lack of robustness and cleanability. Here, we present a simple method for the manufacture of robust self-cleaning ARCs. Our strategy relies on the self-assembly of a block-copolymer in combination with silica-based sol-gel chemistry and preformed TiO2 nanocrystals. The spontaneous dense packing of copolymer micelles followed by a condensation reaction results in an inverse opal-type silica morphology that is loaded with TiO2 photocatalytic hot-spots. The very low volume fraction of the inorganic network allows the optimization of the antireflecting properties of the porous ARC despite the high refractive index of the embedded photocatalytic TiO2 nanocrystals. The resulting ARCs combine high optical and self-cleaning performance and can be deposited onto flexible plastic substrates. © 2013 American Chemical Society.
Agency: European Commission | Branch: FP7 | Program: CP-TP | Phase: NMP.2012.1.4-3 | Award Amount: 2.54M | Year: 2013
Optical coatings are commonly deposited over large areas on different substrates: glass, metals (steel, aluminium...) or polymeric foils (PET...). Production processes involve normally large machinery including many times roll-to-roll processes to deposit multilayers over several square meters of substrates. However, properties of these coatings depend strongly on nanometric properties: composition, crystallography, nanostructure, roughness, homogeneity... Solar selective coatings are considered a special case of optical coatings combining several layers with different properties, mainly: antireflection, solar absorbance and infrared mirror. Nowadays the most demanding solar selective coatings are those used in tubes of high temperature parabolic trough solar collectors. Coatings have to operate in an aggressive environment (temperatures above 400C, thermal cycling) during 20-25 years. Besides, further developments require higher temperatures, improved scratch resistance and working under oxidant atmospheres (small quantities of water vapour and oxygen). In order to get significant advances in this field it is essential to have: 1. Nanoscale structure related requirements (nanoroughness, nanohardness, crystallography, composition, vibrational modes) and the correlation with performance requirements: optical and, more important, life expectancy. 2. Standard characterisation and degradation protocols to serve as a powerful tool to coating developers, producers and end users for life prediction and to push the collector parameters (temperatures and environment) to higher efficiency parameters. The main idea behind this NECSO project is to provide tools to the end users namely solar plants builders, to guarantee that the selective coating will work properly during 20 to 25 years. Novel experimental methods for testing materials under extreme conditions (temperature and radiation) are needed providing a deeper understanding of the interaction of electromagnetic radiation with nanomaterials, as basis for design of new spectrally selective absorber coatings. Nanoscale characterisation (roughness, AFM, nanoindentation, scratch-adhesion, crystallography by FESEM-EBSD, Raman, RX, XPS, etc) will correlate the nanostructure parameters with coating performance. The resulting outcomes are expected to contribute significantly to the infrastructure of the solar energy research, development and industrial activities worldwide. Additionally, the designed testing protocols should help coating developers to compare available layers and newly designed ones, with standard procedures. Finally, testing procedures will also be of utter importance to have a fast quality control on the coatings, typically in 4 meter tubes, over some tens of kilometres in a common cylinder parabolic solar plant.
Hausild P.,Czech Technical University |
Nohava J.,CSM Instruments Inc. |
Pilvin P.,University of Southern Brittany
Strain | Year: 2011
Deformation-induced martensite in metastable austenitic steel was characterised by the grid nanoindentation method. Distribution of nanohardness was found out in specimens with different martensite volume fractions. Bimodal distribution of hardness was only slightly affected by the values obtained on or near γ-α' phase boundary. This approach was verified by independent phase identification using electron back scattered diffraction. © 2010 Blackwell Publishing Ltd.
Zhou B.,CSM Instruments Inc. |
Li Y.,University of Pittsburgh |
Randall N.X.,CSM Instruments Inc. |
Li L.,University of Pittsburgh
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2011
The frictional property of soft contact lenses could have a great impact on their clinical performance. However, to date, only a handful of studies have been conducted to understand the friction mechanism(s) of the soft contact lens. In the current paper, the friction of senofilcon-A contact lenses has been studied with a stainless steel ball as the counterface in a saline solution. The load applied was between 0.5 mN and 100 mN and the sliding velocity ranges from 0.01 cm/s to 0.5 cm/s. It was found that the friction force is proportional to normal load as described by Amonton's law and this unexpected behavior can be attributed to the fact that viscous flow contributes little to the overall friction and that solid-solid contact dominates the friction of senofilcon-A. It was also found that the coefficient of the friction increases with the velocity and the quantitative relationship between them can be explained reasonably well with a previously proposed "repulsion-adsorption" model. The impacts of material chemistry, water content, test media, applied load and the sliding velocity on the friction mechanism(s) are also discussed. © 2011 Elsevier Ltd.
Gong J.,Harvard University |
Lipomi D.J.,Harvard University |
Deng J.,Harvard University |
Nie Z.,Harvard University |
And 4 more authors.
Nano Letters | Year: 2010
This paper describes the use of a nanoindenter, equipped with a diamond tip, to form patterns of indentations on planar substrates (epoxy, silicon, and SiO2). The process is called "Indentation Lithography" (IndL). The indentations have the form of pits and furrows, whose cross-sectional profiles are determined by the shapes of the diamond indenters, and whose dimensions are determined by the applied load and hardness of the substrate. IndL makes it possible to indent hard materials, to produce patterns with multiple levels of relief by changing the loading force, and to control the profiles of the indentations by using indenters with different shapes. This paper also demonstrates the transfer of indented patterns to elastomeric PDMS stamps for soft lithography, and to thin films of evaporated gold or silver. Stripping an evaporated film from an indented template produces patterns of gold or silver pyramids, whose tips concentrate electric fields. Patterns produced by IndL can thus be used as substrates for surface-enhanced Raman scattering (SERS) and for other plasmonic applications. © 2010 American Chemical Society.
Hausild P.,Czech Technical University |
Materna A.,Czech Technical University |
Nohava J.,CSM Instruments Inc.
Materials and Design | Year: 2012
The local stress-strain relations were characterized by instrumented indentation with spherical indenter. The results obtained by indentation with different indenter radii were compared with tensile stress-strain curves of two metastable austenitic stainless steels (grade A301 and A304) and analyzed using finite element model. A forward finite element analysis was also carried out with model material behavior (elastic-perfectly plastic, linear hardening, piece-wise linear hardening and power-law hardening). The limitations of identified stress-strain relations arising from the indenter shape, uneven contact and non-linear material behavior due to the deformation induced martensitic transformation are discussed. © 2012 Elsevier Ltd.
Li H.,Harvard University |
Randall N.X.,CSM Instruments Inc. |
Vlassak J.J.,Harvard University
Journal of Materials Research | Year: 2010
Indentation experiments on thin films are analyzed by using a rigorous solution to model elastic substrate effects. Two cases are discussed: elastic indentations where film and substrate are anisotropic and elastoplastic indentations where significant material pileup occurs. We demonstrate that the elastic modulus of a thin film can be accurately measured in both cases, even if there is significant elastic mismatch between film and substrate. © 2010 Materials Research Society.
Mahabadi O.K.,University of Toronto |
Randall N.X.,CSM Instruments Inc. |
Zong Z.,CSM Instruments Inc. |
Grasselli G.,University of Toronto
Geophysical Research Letters | Year: 2012
The mechanical response of geomaterials is highly influenced by geometrical and material heterogeneity. To date, most modeling practices consider heterogeneity qualitatively and their choice of input parameters can be subjective. In this study, a novel approach to combine a detailed micro-scale characterization with modeling of heterogeneous geomaterials is presented. By conducting grid micro-indentation and micro-scratch tests, the instrumented indentation modulus and fracture toughness of the constituent phases of a crystalline rock were obtained and used as accurate input parameters for the numerical models. Additionally, X-ray micro Computed Tomography (CT) was used to obtain the spatial distribution of minerals, and thin section analysis was performed to quantify the microcrack density. Finally, a Brazilian disc test was modeled using a Combined Finite-Discrete element method (FEM/DEM) code. Compared with the laboratory results of a sample that was initially CT scanned, the simulation results showed that by incorporating accurate micromechanical input parameters and the intrinsic rock geometric features such as spatial phase heterogeneity and microcracks, the numerical simulation could more accurately predict the mechanical response of the specimen, including the fracture patterns and tensile strength. It is believed that the proposed micromechanical approach for evaluating the material properties and the sample geometry can be readily applied to other problems to accurately model the mechanical behavior of heterogeneous geomaterials. Copyright 2012 by the American Geophysical Union.
Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: NMP.2012.4.0-2 | Award Amount: 492.57K | Year: 2012
This project will further develop, validate and draft standards for nano-scratching, which is an important new tool to investigate the tribological properties of materials on a scale relevant to the fundamental mechanisms of wear. It will facilitate the development of new coatings and engineered surfaces that will give impact through improved competitiveness of industry and a better quality of life for EU citizens. Nano-scratching clearly operates at a different length scale to macro- and micro-scratch tests, but can be a straightforward extension of the capability of nanoindentation equipment. This is an area where European industry is very strong, three European SMEs have a dominant role in production of such instruments. In scratching a sharp, stiff tool is moved on the surface of the sample while a normal force is applied on the tool tip. At different threshold values of the force the tip penetrates into the sample by various mechanisms. These threshold forces, or more precisely the stresses that are generated at these thresholds, are characteristic parameters for the failure of the substrate-coating system in question. Test procedures and software for nano-scratching are in their infancy compared to those for nanoindentation. Development of nanoindentation equipment started on a firm theoretical basis, while nano-scratching (as macro-scratching) has no uniform methodology till now. One part of the NANOINDENT FP-7 project (NMP3-CA-2008-218659) dealt with the development of nano-scratching metrology, guidelines for determining scratching data were constituted. Based on these studies, NANOINDENT partners have set up this new proposal to start a standardisation process. The overall aim of the project is to draft a New Working Item Proposal (NWIP) for a standard in nano-scratching that will be submitted to the appropriate CEN technical committee (TC 352) through a workshop of the main European stakeholders from industry, academia, and research organizations.