a b s t r a c tThe role played by graphene in the friction and wear behaviour of graphene/silicon carbide (SiC) composites, tested under dry sliding conditions and using silicon nitride balls as counterbodies, is investigated as a function of the graphene nanoplatelets (GNPs) content and the graphene source. GNPs composites show an enhanced wear resistance as compared to monolithic SiC, with maximum improvements of ∼70% for the material containing up to 20 vol.% of GNPs; whereas the friction performance depends on the sliding distance and GNPs content. The analysis of the wear debris by micro-Raman spectroscopy evidenced that the tribological behaviour of the GNPs/SiC materials is linked to the formation of an adhered lubricating and protecting tribofilm. Multilayered graphene fillers participate more actively in the protecting tribofilm than other graphene sources such as reduced graphene oxide or in-situ grown graphene flakes.

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Abstract-Scalability and photonic integration of packet switched cross-connect nodes that utilize all-optical signal processing is a crucial issue that eventually determines the future role of photonic signal processing in optical networks. We present a 1 4 all-optical packet switch based on label swapping technique that utilizes a scalable and asynchronous label processor and label rewriter. By combining in-band labels at different wavelengths Index Terms-Label processor, label rewriter, label swapping, optical packet switching, optical signal processing, semiconductor optical amplifier (SOA), wavelength converter.

The tribological performance of silicon carbide (SiC)/graphene nanoplatelets (GNPs) composites is analysed under oscillating sliding tests lubricated with isooctane, looking to explore their potential as components for gasoline direct injection (GDI) engines. High graphene filler contents (20 vol.% of GNPs) are required to substantially reduce the friction coefficient of SiC ceramics, attaining decreases on friction up to 30% independently of the applied load. For all materials and testing conditions a mild wear regime is evidenced. SiC/20 vol.% GNPs composite also enhances the wear resistance up to 35% at low load, but the addition of GNPs produces a deleterious effect as the load augments. The tribological behaviour depends on the formation and destabilization of a solid lubricant carbon-based tribofilm and strongly correlates with the mechanical properties of the tested materials.

The aim of this work is to investigate the effect of large graphene nanoplatelets (GNPs) additions on the friction and wear of silicon nitride (Si 3 N 4 ) ceramics using linear reciprocating ball-on-plate tests lubricated with isooctane. All Si 3 N 4 /GNPs composites, with up to 20.6 vol.% of graphene fillers, exhibit better tribological response than Si 3 N 4 , in particular, a 50% reduction in the friction that continuously decreases with the GNPs content is attained, jointly with an improvement in the wear resistance of up to 63%.The survival of a self-lubricant carbon-rich tribolayer formed on the worn surfaces controls the tribological properties of the materials. These results are very promising to further explore the use of Si 3 N 4 /GNPs composites in high pressure gasoline direct injection systems.