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Presents a study which looks at whether cartel formation is influenced by periods of downtown and in industries with significant sunk cost. What can cartel formation be associated with; Investigation on the emergence of the Swiss dyestuff export cartel during the inter-war period; Results of the study.

Finite element (FE) computations have been performed to analyze the thermo-chemo-mechanical behavior of SiC-based refractory parts in linings used in waste-to-energy plants. These parts are in contact on one side with smoke and ashes at high temperature, and on the other side with the pressurized vapor pipe. Three multi-layered lining designs have been studied: two with tiles and one with a concrete panel. A coupled model taking into account the transport of dioxygen in the gas through the porosity, the reaction of dioxygen in contact with silicon carbide particles and the formation of solid components gradually clogging the pores, has been implemented in the finite element code ABAQUS ® . These phenomena affect the mass diffusion rate of dioxygen through the refractory layer and induce a macroscopic swelling of the material. The analysis of the numerical results allows for a better understanding of the influence of the lining design and the nature of the ceramics on the lifespan of such refractory parts. [ABSTRACT FROM AUTHOR]

Highlights: [•] The goal is the prediction of shape of SiC-based refractory part after long term oxidation. [•] The model takes into account oxygen diffusion through porosity and reaction with SiC grains in matrix. [•] The model takes into account the clogs of the porosity network. [•] The mechanical behaviour account for the local expansion induced by oxidation. [•] A long term oxidation test under thermal gradient was performed. [•] There is a good agreement between final experimental shape and numerical prediction. [Copyright &y& Elsevier]

A uniaxial compression test was performed on a green compacted alumina powder. Using Digital Image Correlation (DIC), displacement fields of two perpendicular surfaces of the specimen were measured showing unavoidable bending effect. A constitutive model was calibrated through three Finite Element Model Updating approaches. First, an analysis was performed using average axial strains assessed via DIC and resultant forces to identify the constitutive model. Then, a plane stress analysis was conducted out using the displacements of the boundaries of the regions of interest for each camera separately to obtain the sought parameters. Last, a 3D analysis was carried out using the multi-point constraint method to link displacement fields of both surfaces. Because of bending, the first two approaches give rise to two sets of different parameters. The analysis that considers the 3D nature of bending leads to the set of parameters with the highest degree of confidence. Unlabelled Image • DIC was applied for two perpendicular surfaces of a uniaxially compressed specimen. • Undesirable (but unavoidable) bending effects were characterized. • A 3D analysis was carried out by coupling the DIC displacements fields on the two faces. • Parameters of a constitutive model were calibrated using three different FEMU approaches. [ABSTRACT FROM AUTHOR]

Abstract Cold uniaxial pressed PTFE compacts were subjected to thermal cycles of increasing maximum temperature below melting temperature, and thermal expansion was followed in both the compaction and transverse directions. The measurements reveal that thermal expansion consists of two distinct contributions: i) an irreversible part that is controlled only by the maximum temperature experienced by the sample, and ii) a reversible, or thermo-elastic, part that is observed while cycling below the maximum temperature. Moreover, both of these thermal strains exhibit marked anisotropy, resulting from the cold oedometric compaction of the sample. A quantitative analysis of these eigenstrains is proposed, following a formal analogy with elasto-plasticity. Finally, it is shown that such behavior is specific to cold-pressed compacts as sintered samples exhibit isotropic and purely reversible thermo-elastic behavior. Highlights • Thermal expansion of cold pressed PTFE compacts contains two anisotropic contributions, one reversible and one irreversible. • Dilatometric measurements during repeated cycles of increasing amplitude allows these two contributions to be distinguished. • The irreversible part of the thermal expansion is controlled solely by the maximum temperature experienced by the sample. [ABSTRACT FROM AUTHOR]

The manufacturing of polytetrafluoroethylene products is usually carried out by cold isostatic and/or uniaxial pressing of the powdered polymer, followed by sintering of the “green” parts. During pressing, the air initially present in the loose powder leads to the formation of defects in the material, but the mechanisms involved are not entirely understood. The aim of this study was to better understand the role played by the entrapped air during the cold pressing of polytetrafluoroethylene powder. Observation of the microstructure and determination of some mechanical properties of green and sintered samples, manufactured with different quantities of entrapped air by the cold isostatic pressing process, were carried out. The analysis indicated that defects are formed when the entrapped air pressure in the pressed part leads to internal stresses exceeding the intergranular cohesion resistance of the green part. These defects remain in the microstructure even after sintering, considerably reducing the mechanical strength. [ABSTRACT FROM AUTHOR]

PTFE presents an original secondary crystallization that appears to be independent of the primary one. The conjunction of differential scanning calorimetry and dilatometry experiments has offered complementary data to study both crystallization melted compacted powder and of recrystallized samples. The primary crystallization is responsible for the crystallinity content variation with the cooling rate. It preserves the anisotropy induced by previous compaction that can be observed by dilatometry. Conversely, the secondary crystallization appears to be instantaneous, reversible, kinetic-free and isotropic. It occurs over a wide temperature range between 250°C and 310°C. • Two independent crystallization mechanisms for PTFE are proposed. • The rate-limited primary crystallization sets the final crystallinity content. • It inherits from uniaxial pressing of an anisotropy revealed in dilatometry. • In contrast, the secondary crystallization is instantaneous and fully reversible. • The secondary crystallization appears to be isotropic. [ABSTRACT FROM AUTHOR]