Interfacce nei compositi a matrice inorganica

Study of the interfaces in the inorganic-matrix composites. Different kinds of composites have been synthetized and characterized, focusing the attention on the role of the interfaces between the matrix and the dispersed phase. One aim of the research activity was the optimization of the sintering process of particle-reinforced glass matrix composites to obtain densities as close as possible to the theoretical value and improved mechanical properties in comparison with the parent glass matrix. A pressureless sintering process has been studied by means of heating-microscopy, differential scanning calorimetry and dilatometry on glass powders and mixtures of glass and reinforcement powders. Particular attention was focused on the oxidation and reduction reactions, as well as on the dissolution phenomena develpoed at the inerface between the oxidized surface layer of metal paticles and the softened glass marix during the sinering process. The chosen glass matrix composites have the following compositions: (1) 5, 10 and 20 wt% Ti particle-reinforced ZnO-B2O3-PbO based glasses; and (2) 5, 10 and 20 wt% Ti particle-reinforced TiO2-ZnO-B2O3-PbO based glasses. These glasses were suitable as 'model' glasses, and the method was then extended to other glass matrixces, in particular to several bioactive glass-matrices, aiming to prepare bioactive composites reinforced by titanum particles, to be used as bulk or coatings on metallic substrates for load bearing applications. A second aim of the research was the study of the interfaces between 2024 Aluminium alloys and SiC wiskers in metal matrix composites. The attention was focused on the role of dislocations in proximity of the dispersed phase on the precipitation kinetics of intermetallic phases in the metal matrix.