Chemical Vapor Deposited Silicon Carbide Turbine Rotors

In a ceramic gas turbine, the rotor is the component with the most demanding requirements, and its performance limits will determine the turbine operating conditions. Chemical vapor deposited (CVD) silicon carbide (SiC) has been shown to be one of the most promising materials considering strength, creep, oxidation, fabricability, and cost. The CVD process has produced rotors in the desired configuration and test samples with strengths of 100 ksi at 1400°C and peak values of 200 ksi at 1500°C. CVD SiC is a pure material with very low creep rates showing potential for operation to 10,000 h and possibly beyond at 1600°C and 30 ksi compared to 1000 h at 1200°C and 10 ksi for the best silicon nitride (Si₃N₄) available. Under equal heat flux conditions, the thermal stress generated in CVD SiC is similar to Si₃N₄, and CVD SiC has superior oxidation resistance to other materials tested.