Speaker
Description
Lightweight metal and ceramic matrix composites (MMCs and CMCs) reinforced by high-strength continuous fibers emerge as ideal structural materials in several applications, such as automotive, aircraft and aerospace due to their superior high-temperature strength, low density, improved damage tolerance and corrosion resistance.
Today, the most extensively studied CMCs are reinforced by C- and SiC fibers, namely C/Cf, Cf/SiC, SiCf/SiC and C/C-SiC composites. Despite the manufacturing processes of fibers have reached a high level of reproducibility, their use is limited by the costs and difficulties encountered in producing successfully large and complex CMCs shapes, by their assembling and integration with dissimilar materials, i.e., metals, ceramics or other composites and by the fiber degradation during the fabrication processes and in service, mainly at high temperature. Indeed, Cf and SiCf show the tendency to be oxidized and degraded (i.e. by releasing CO and SiO) if processed at temperature above 400°C and 1200°C under oxidizing atmospheres, respectively.
Reliable densification and joining of CMCs by liquid assisted processes are crucial for preserving the CMC thermo-mechanical properties and for saving weight. Both densification and joining property reliability are ensured by the microstructures resulting from the interaction phenomena occurring at the metal/fiber interfaces.
In this work, the results successfully achieved in using the two Si-16.2Ti and Si-86.5Ti (in at.%) eutectic alloys used as coating (Figure 1) and filler materials for CMCs are presented, as well as the efficient combined theoretical-experimental investigations preliminarly performed on the interfacial phenomena occurring between the liquid eutectic alloys in contact with C and SiC.
Figure 1. Cf/C coated by Si-86.5at%Ti at T = 1350°C under a vacuum.
| Speaker Country | Italy |
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