Si-SiC-ZrB2 ceramics by silicon reactive infiltration

Silicon carbide ceramics obtained by silicon reactive infiltration are nowadays employed within industry in several high temperature applications. Although these ceramics show good thermo-mechanical properties and oxidation resistance, they suffer temperature limitations (1400 °C). At higher temperatures another type of ceramics, commonly known as ultra high temperature ceramics (UHTCs), is under study. These include the transition metal diborides of group IV; one in particular, zirconium diboride, is interesting in certain applications (e.g. aerospace) because of its low relative density. ZrB2-SiC ceramics show good thermo-mechanical properties and maintain the “protective” passive oxidation regime of their scales over a wide range of temperatures. This paper presents a feasibility study on a manufacturing methodology to produce Si-SiC-ZrB2 bulk ceramics taking advantage of the reactive infiltration technique. This technique allows lower processing temperatures and near to net shape capability due to low shrinking of the green compacted bodies. C-SiC-ZrB2 preforms were successfully infiltrated with molten silicon. The resulting Si-SiC-ZrB2 composites showed promising oxidation behavior, similarly to that reported in other works. Bulk material optimization was performed with a view to manufacturing Si-SiC-ZrB2 ceramic matrix composites by silicon reactive infiltration in future.