In horizontal continuous casting or in meniscus free continuous casting, the appearance of corrugations or marks at the surface of the cast products cannot be related with the partial solidification of the meniscus of the free surface of the liquid metal, like in the case of the classical vertical continuous casting process. In order to find their origin, an experimental work has been carried on with two different experimental devices. The first one provides solidified metallic samples to be observed and analysed. With the other one, it is possible to directly look at the formation of the skin on the mould during the solidification of transparent organic compounds. Here, we firstly present the results of the observation of the surface of samples cast in very different casting conditions. In a companion paper, we propose a description of the formation of the marks and corrugations in terms of basic phenomena which occur during solidification.

The work presents results of investigations and microstructural analyses for Mg- SiCp cast composites. The metallographic examination shows that the distribution of SiC particles is uniform. Quantitative image analysis of the microstructure shows the magnesium grain size to be smaller and more uniform than in the base metal. The studies at the level of the interfaces suggest that the bonding between the matrix and the reinforcement is of the adhesive type. The presence of the Mg2Si compound in the composites has also been revealed. Additionally, some compounds seem to be present at the SiC/matrix interface. The performed analyses have allowed to propose a model description of the process of the formation of the Mg-SiC composite structure. Mechanical testing has shown that composites have increased YoungÕs modulus and proof stress (R$_{{\rm p 0,2}}$) and decreased impact strength.

In order to explain and simulate the behaviour of real, complex gas-solid reactive systems, we developed a new kinetic model which describes the coupled phenomena of chemical reaction, diffusion, heat transfer and porosity evolution. The model was successfully applied to the hydrofluorination of uranium dioxide. The difference in reactivity between two dioxides has been related to their initial pore structure and its evolution.

The influence of tensile stresses coupled with temperature cycling has been determined on a Cu-Zn-Al shape memory alloy that transforms above room temperature. It is shown that the application of increasing stresses during thermal cycles leads to an increasing martensite stabilization. The repeated thermal cycling with constant stress as well as slow temperature rates increase the stabilization. This phenomenon is attributed to a pinning of austenite-martensite interfaces by vacancies. This hypothesis is confirmed by the comparison of experiments with continuous and with stepwise temperature variations.

C-Mn steels and their welds are sensitive to the dynamic strain ageing (DSA) phenomenon. The DSA sensitivity of different weld zones is not well known. Therefore, the influence of microstructure in the heat affected zones, the effect of post weld heat treatment and the effect of the chemical composition (manganese content) of the deposited metal were studied by correlation between tensile tests and internal friction tests (mechanical spectroscopy).

Polypyrrole films are electrodeposited on zinc and other common metals in a one- step process by using a salicylate salt in a pH 5 aqueous solution of pyrrole. This electrolyte passivates the substrate and makes it possible to obtain strongly adherent PPy films, with controlled thickness by electrolysis at constant current. With this technique, the current efficiency is high and the deposition rate is high enough to be compatible with the imperatives of industrial production (2 μm in 3 s with a 200 mA/cm2 current density).

Deposition of zirconia inside hollow substrates in remote Ar-O2-H2 post- discharges is considered. The inner surface of cylindrical substrates is coated by a thin film of monoclinic zirconia at 573 K and above. A complete modelling, required to control the process, is developed by solving the conservation equations of continuity, momentum and energy. By this means, the thickness homogeneity of the layers is improved and almost constant deposition rates are obtained along the substrate.

The observation and Raman analysis of the surface of a PET polymer after the impact of an aluminium particle, combined with thermal modelling, have shown the presence of a zone with modified crystallization. This heat affected zone, with a thickness of a few microns, has different shapes depending on the geometry of the splat particle which is at its origin. This is the sign of a sharp temperature increase followed by a very rapid cooling. As a result, the proposition of crystallized phase is gradually decreased, and an amorphous phase is formed in a thin layer close to the surface. These results have been used to develop a protective plasma spraying technique for the coating of organic parts.

The acoustic near field method consists in studying the alteration of the resonance curve of a horn whose tip, the probe, is immersed in the sample. The operating mode in a medium in which strong variations of the rheological properties take place, is modelled for two horn shapes, one with a conical probe, the second one with a stepped cylindrical probe. The experimental curves obtained during the cement setting prove the validity of the simulations. The sensitivity of the horn to a given step of the setting is achieved by adjusting the probe shape.