Philippe Thomas

Contribution to the Understanding of Tribological Properties of Graphite Intercalation Compounds with Metal Chloride

Intrinsic tribological properties of lamellar compounds are usually attributed to the presence of van der Waals gaps in their structure through which interlayer interactions are weak. The controlled variation of the distances and interactions between graphene layers by intercalation of electrophilic species in graphite is used in order to explore more deeply the friction reduction properties of low-dimensional compounds. Three graphite intercalation compounds with antimony pentachloride, iron trichloride and aluminium trichloride are studied. Their tribological properties are correlated to their structural parameters, and the interlayer interactions are deduced from ab initio bands structure calculations.

Macro- and Nanotribological Properties of Graphite Tribofilms: Influence of the Sliding Interface

Macrotribological studies of microcrystalline graphite powder reveal a drastic decrease in the friction coefficient when the experiments are carried out in the presence of low-viscosity liquids. The friction reduction is attributed to the simultaneous presence of particles and liquid in the sliding contact, but the mechanisms involved remain unclear. In order to contribute to the understanding of liquid action in friction reduction mechanisms, nanoscale investigations of the tribofilms have been performed using lateral force microscopy. Attention is devoted to the nanostructure of the film surfaces and their nanofriction behavior using an atomic force microscope. The influence of the tip/sample interfaces on friction properties is investigated by using AFM tips constituted of different compounds (silicon, gold/chromium alloy, silicon nitride or carbon-covered AFM tip) and by performing the nanofriction tests in air or liquid environments. The results indicate that the friction reduction observed at macroscale is attributed neither to the lowering of the shear strength of the carbon/carbon interface in the presence of liquid nor to the nanostructure of the film surface. Collective liquid/particles effects inside the contact during sliding are probably involved.

FIB, TEM and AFM Quantitative Investigation of Nanostructure and Nanoscale Friction Properties of Single Partially Fluorinated Carbon Nanofibres

1. Groupe de Technologie des Surfaces et des Interfaces (GTSI EA 2432) 2. risation des Mat des Antilles et de la Guyane, Campus Fouillole, BP 250 97 157 Pointe à Pitre – Guadeloupe-FranceFrench West Indies 3. EDF R&D, Department MMC and MAI, Avenue des Renardiè res, 77818 Moret sur Loing Cedex 4. Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF, UMR 6296), Inorganic Materials team, 63177 Aubière, France

Analytical Transmission Electron Microscopy Investigation of the Fluorination Process of Carbon Nanoparticles.

1 Groupe de Technologie des Surfaces et des Interfaces (GTSI EA 2432) 2 Centre Commun de Caractérisation des Matériaux des Antilles et de la Guyane, Université des Antilles et de la Guyane, Campus Fouillole, BP 250 97 157 Pointe à Pitre – Guadeloupe-France-French West Indies 3 Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF, UMR 6296), Inorganic Materials team, 63177 Aubière, France