Extrinsic Measurement of Carbon Black Aggregate Distribution within a Fluoroelastomer Matrix from Nanoindentation Experiments.

A novel extrinsic method for the measurement of particle surface distribution in a carbon black-filled elastomer via nanoindentation is developed. This method is based on the measurement of the contact stiffness obtained from the continuous stiffness measurement mode. The proposed tip-particle model is held by two main hypotheses: the particles do not deform significantly during indentation so that only the elastomer matrix elastically deforms; particles are physically bounded with the surrounding matrix. Therefore, when the tip comes in contact with a particle, the latter becomes a hard extension of the tip, able to deform the elastomer matrix. Finally, the evolution of the measured contact stiffness is directly related to the increase of the contact area between the tip-particles set and the elastomer matrix. The proposed model is validated through a numerical and an experimental study. Moreover, an evaluation of the measurements bias allows to correct the particle surface distribution. A good agreement is found between the distribution measured from transmission electron microscopy observations and nanoindentation measurements.

Locally measuring the adhesion of InP directly bonded on sub-100 nm patterned Si.

A nano-scale analogue to the double cantilever experiment that combines instrumented nano-indentation and atomic force microscopy is used to precisely and locally measure the adhesion of InP bonded on sub-100 nm patterned Si using oxide-free or oxide-mediated bonding. Surface-bonding energies of 0.548 and 0.628 J m(-2), respectively, are reported. These energies correspond in turn to 51% and 57% of the surface bonding energy measured in unpatterned regions on the same samples, i.e. the proportion of unetched Si surface in the patterned areas. The results show that bonding on patterned surfaces can be as robust as on unpatterned surfaces, provided care is taken with the post-patterning surface preparation process and, therefore, open the path towards innovative designs that include patterns embedded in the Si guiding layer of hybrid III-V/Si photonic integrated circuits.

Development of a synchrotron biaxial tensile device for in situ characterization of thin films mechanical response.

We have developed on the DIFFABS-SOLEIL beamline a biaxial tensile machine working in the synchrotron environment for in situ diffraction characterization of thin polycrystalline films mechanical response. The machine has been designed to test compliant substrates coated by the studied films under controlled, applied strain field. Technological challenges comprise the sample design including fixation of the substrate ends, the related generation of a uniform strain field in the studied (central) volume, and the operations from the beamline pilot. Preliminary tests on 150 nm thick W films deposited onto polyimide cruciform substrates are presented. The obtained results for applied strains using x-ray diffraction and digital image correlation methods clearly show the full potentialities of this new setup.

Ti-Si-C thin films produced by magnetron sputtering: correlation between physical properties, mechanical properties and tribological behavior.

Ti-Si-C thin films were deposited onto silicon, stainless steel and high-speed steel substrates by magnetron sputtering, using different chamber configurations. The composition of the produced films was obtained by Electron Probe Micro-Analysis (EPMA) and the structure by X-ray diffraction (XRD). The hardness and residual stresses were obtained by depth-sensing indentation and substrate deflection measurements (using Stoney's equation), respectively. The tribological behavior of the produced films was studied by pin-on-disc. The increase of the concentration of non-metallic elements (carbon and silicon) caused significant changes in their properties. Structural analysis revealed the possibility of the coexistence of different phases in the prepared films, namely Ti metallic phase (alpha-Ti or beta-Ti) in the films with higher Ti content. The coatings with highest carbon contents, exhibited mainly a sub-stoichiometric fcc NaCI TiC-type structure. These structural changes were also confirmed by resistivity measurements, whose values ranged from 10(3) omega/sq for low non-metal concentration, up to 10(6) omega/sq for the highest metalloid concentration. A strong increase of hardness and residual stresses was observed with the increase of the non-metal concentration in the films. The hardness (H) values ranged between 11 and 27 GPa, with a clear dependence on both crystalline structure and composition features. Following the mechanical behavior, the tribological results showed similar trends, with both friction coefficients and wear revealing also a straight correlation with the composition and crystalline structure of the coatings.

TEM-nanoindentation studies of semiconducting structures.

This paper reviews the application of nanoindentation coupled with transmission electron microscopy (TEM) to investigations of the plastic behaviour of semiconducting structures and its implication for device design. Instrumented nanoindentation has been developed to extract the mechanical behaviour of small volumes scaled to those encountered in semiconductor heterostructures. We illustrate that TEM is a powerful complementary tool for the study of local plasticity induced by nanoindentation. TEM-nanoindentation allows for detailed understanding of the plastic deformation in semiconducting structures and opens practical routes for improvement of devices. Performances of heterostructures are deteriously affected by dislocations that relax the lattice mismatched layers. Different ways to obtain compliant substructures are being developed in order to concentrate the plastic relaxation underneath the heterostructure. Such approaches allow for mechanical design of micro- and opto-electronic devices to be considered throughout the fabrication process.

Detecting enteropathogenic strains of Escherichia coli of porcine origin. 2. Relationship between O and K antigens and the production of enterotoxin in strains isolated from the piglet after weaning.

The production of enterotoxin by biological tests (Yl adrenal cells and the suckling mouse) has been examined in 96 strains of Escherichia coli, isolated from sick piglets after weaning. There is a good correlation between the presence of the capsular antigen K88 and that of the thermolabile fraction (LT) of the enterotoxin (69.2 per cent of the enteropathogenic strains studied). However, the presence of the thermostable fraction (ST) of the enterotoxin of strains which, according to their serological grouping, possess in theory the two fractions LT + ST or only the ST fraction is only confirmed in a small number of strains (16 per cent) by the biological test.

Detecting enteropathogenic Escherichia coli strains of porcine origin. 1. Correlations between O and K antigens and the enterotoxin production in strains isolated from the newborn piglet.

A study of enterotoxin production by means of biological tests (Y1 adrenal cells and suckling mice) using 67 Escherichia coli strains responsible for diarrhea in newborn piglets, confirmed the advantages of these methods and demonstrated the correlation between antigenic specificity and enterotoxin production. In particular the presence of capsular antigen K 88 is related to the thermolabile (LT) fraction of the enterotoxin in 73.9 % of the enteropathogenic strains studied.