Reaction Bonded Silicon Carbide and Silicon Nitride for Gas Turbine Applications

Two unique ceramic materials offer the gas turbine designer the opportunity to substitute uncooled high temperature components for the presently cooled metal and alloy ones. Recrystallized silicon carbide made by a casting process and reaction bonded silicon nitride shaped by a simple machining process before firing, offer not only high temperature materials capable of living in the gas turbine environment, but also an intricacy of shape consistent with combustor, shroud and associated high temperature component needs. Silicon carbide’s 3200 F capability and its thermal shock resistance makes it a sound choice; silicon nitride’s low expansion coefficient, thermal shock resistance, and 2900 F capability make it a material of real merit. The properties of these materials are discussed in detail along with potential areas of application and design capabilities.