Influence of glass/mould interfaces on sticking

The sticking of glass on mould materials is a critical problem since it can lead to the Interruption of glass Container production. This study is a contribution to understanding the phenomena at the origin of sticking. The experiments involve loading and spreading glass gobs on flat metallic Substrates. They are performed directly on a glassmaking machine, thus the thermal conditions of the processes are simulated as closely as possible. Special attention is paid to characterizing the metal and glass surfaces before and after contact using a surface profilometer, AFM, and SEM with an EDX spectrometer. The influence on sticking of mould temperature, surface roughness and surface chemistry (nonoxidized, pre-oxidized and lubricated) is investigated

Wetting and energetics in nanoparticle etching of graphene

Molten metallic nanoparticles have recently been used to construct graphene nanostructures with crystallographic edges. The mechanism by which this happens, however, remains unclear. Here, we present a simple model that explains how a droplet can etch graphene. Two factors possibly contribute to this process: a difference between the equilibrium wettability of graphene and the substrate that supports it, or the large surface energy associated with the graphene edge. We calculate the etching velocities due to either of these factors and make testable predictions for evaluating the significance of each in graphene etching. This model is general and can be applied to other materials systems as well. As an example, we show how our model can be used to extend a current theory of droplet motion on binary semiconductor surfaces

An Overview on Ancient Quarries of Southeastern Attica. The Ancient Quarries of Hymettus Revisited

Based upon the information about the quarries of southeastern Attica presented in Kokkorou-Alevras et al. (2014), the research group of the National and Kapodistrian University of Athens has tried to throw light on the quarrying activity, that took place in these quarries during the antiquity and to update, to a certain degree, the data from past publications. New investigations were conducted in areas where ancient quarries had been located in the past (e.g. in Rhamnous, Marathon, Brauron, etc.) and important knowledge has been added about the quarrying activity of that region in antiquity. Our research focused on the Hymmetus marble quarries and was based upon both a new systematic investigation of the ancient quarry-faces on mount Hymettus and a search for possible unknown and smaller quarries on the mountain. Our work led us to a re-evaluation of the attested quarry-marks and the quarrying techniques on the extensive working-faces, as well as to a better understanding of the actual scale of the extraction and thus to a re-estimation of the bulk of the extracted blocks. Furthermore, we came to new conclusions about the scale of stone extraction during the Archaic period, judging from the distinctive technical features observed on the quarried rock

Wetting, interfacial interactions and sticking in glass/steel systems

Wetting and sticking of soda-lime glass on two types of stainless steel as well as on platinum and vitreous carbon substrates are studied in a neutral gas atmosphere between 860 and 1200degreesC. Wetting is measured by the "transferred drop" version of the sessile drop technique, enabling fully isothermal spreading kinetics to be monitored. Sticking is investigated by measuring the temperature of glass drop detachment from the substrate during cooling below the vitreous transition temperature. Characterization of substrate and glass surfaces after separation is carried out using surface profilometry, atomic-force microscopy (AFM) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy. The character of molten glass wetting on metal (reactive or non-reactive) and the type of interactions ensuring ultimate wetting and adhesion (physical or chemical) are identified and discussed. The factors controlling glass spreading kinetics and those governing glass/steel sticking are also evidenced. (C) 2004 Elsevier B.V. All rights reserved

Metal matrix syntactic foams produced by pressure infiltration—The effect of infiltration parameters

Metal matrix syntactic foams (MMSFs) were produced by pressure infiltration. Two parameters of the infiltration process (pressure and time) were varied and the infiltrated length was measured as the function of infiltration parameters in order to get data for the implementation of pressure infiltration as mass-production of MMSFs similar to injection mould casting, especially in the short infiltration time range (<10 s). The infiltrated length was found to be linear function of pressure and square-root function of time. The effect of the infiltration parameters on the microstructure and mechanical properties of MMSFs were investigated by optical microscopy and standardised compression tests. The microscopic images were used to qualify the pressure infiltration and showed that more than one combination of infiltration parameters can be found for successful production of a part with given required dimensions. Considering the compression tests, the main characterising properties were mapped as function of infiltration parameters. The registered values showed dependency on the infiltration parameters and indicated that a given infiltration length produced by higher pressure and shorter time has better mechanical properties. The infiltrated specimens were isotropic, anisotropy was not observed in the reference measurements

A tight-binding potential for atomistic simulations of carbon interacting with transition metals: Application to the Ni-C system

We present a tight-binding potential for transition metals, carbon, and transition metal carbides, which has been optimized through a systematic fitting procedure. A minimal basis, including the s, p electrons of carbon and the d electrons of the transition metal, is used to obtain a transferable tight-binding model of the carbon-carbon, metal-metal and metal-carbon interactions applicable to binary systems. The Ni-C system is more specifically discussed. The successful validation of the potential for different atomic configurations indicates a good transferability of the model and makes it a good choice for atomistic simulations sampling a large configuration space. This approach appears to be very efficient to describe interactions in systems containing carbon and transition metal elements