Electrophoretic deposition of ZrB2 and SiC powders on woven carbon fibers for the processing of novel UHTCMCs

In the present work, the deposition of Zirconium diboride (ZrB2) or/and Silicon carbide (SiC), on carbon fibers via electrophoretic (EPD) is studied. The final purpose is the fabrication of novel UHTCMCs for aerospace, with optimized fiber/matrix interface Ceramic coatings are indeed necessary for optimization of the fiber/matrix bonding, oxidation protection and prevention of fiber-matrix interfacial degradation at elevated temperatures. Ethanol-based Ceramic suspensions of ZrB2 or/and SiC powders have been studied in order to find the suitable solid concentration and dispersant amount, poly(ethyleneimmine) (PEI), for the deposition. PEI was found to be effective for the dispersion of both ZrB2 and SiC powders in ethanol solution. The d.d.p. (Volt) applied to the electrophoretic cell was varied from 5 to 30 Volt with holding times between 5 and 180 minutes. An incremental approach was adopted starting from deposition on to individual bundles, and then unidirectional carbon fabrics, to end with 2D carbon fabrics. The unidirectional coated woven carbon fibers were further infiltrated with a ceramic slurry, overlapped and treated by hot pressing for densification. The microstructure of the polished sections of carbon fibers and unidirectional fabrics coated was examined by scanning electron microscopy and optical microscopy. The structure obtained by the combination of these techniques is typical of a new generation of materials defined ultra high temperature ceramics matrix composites (UHTCMC), which can potentially couple the high oxidation resistance of UHTCs to the damage tolerance of CMCs, provided that a suitable matrix/fiber interface is tailored.