DIRECT METALLIC COVERING FIBER PROCESS: FIRST STUDY AND PRELIMINARY APPROACH

INTRODUCTION Replacing steel with light materials in transport would result in lower fuel consumption and therefore less CO2 emissions into the atmosphere. Metals like aluminum and magnesium have a specific weight that is much more inferior to commonly used steels, but also poor mechanical properties. For this reason, the need arises to reinforce the metal matrix with the introduction of fibers. Nowadays, attention is being focused on reinforcements of natural origin in order to reduce the environmental impact of non-recyclable materials. Basalt, is an effusive rock of volcanic origin with excellent mechanical and thermal resistance properties, is becoming increasingly important. In order to promote its compatibility with the matrix (generally polymeric, PMC) it is customary to cover the single filaments with a polymeric sizing. Likewise, metal-coated filaments could be obtained for subsequent use in metal matrix composites (MMC). In this work we discuss the changes made to a standard basalt and glass spinning plant replacing the polymeric sizing application system with a molten metal deposition chamber in order to obtain a coating of the fibers directly during the spinning procedure. MATERIAL AND METHODS The exploration phase was carried out using pure aluminium as covering metal, which has lower flammability and usage problems than magnesium, but at the same time the analogy between their melting temperatures would allow the same plant to be used for both. E-glass and basalt fibers were used as raw material to obtain the single filaments covered with aluminium. Morphology and interface between aluminium and fibers were investigated by SEM and EDS analysis. RESULTS AND DISCUSSION The variation of some parameters, such as the speed of rotation of the winder and the temperature of the molten metal bath, allowed to obtain different metal thicknesses and different mechanical properties. Tensile tests on single filament were performed to investigate the potential effect of the metallic covering on mechanical properties of fibers and results show a that basalt filaments highlight a better resistance to aluminium melting temperature (660 °C) compared to E-glass filaments. With this method it would be possible to disperse even submicrometric or nanometric particles in the fibers metal covering obtaining a perfect homogeneity of dispersion in the composite that would be obtained subsequently with their use.