Brittle Materials Design, High Temperature Gas Turbine

TLDR: In this article, an uncooled brittle materials in structural applications at 2500 F is the objective of the 'Brittle Materials Design, High Temperature Gas Turbine' program.

Abstract: : The demonstration of uncooled brittle materials in structural applications at 2500 F is the objective of the 'Brittle Materials Design, High Temperature Gas Turbine' program. Ford Motor Company, the contractor, will utilize a small vehicular gas turbine while Westinghouse, the subcontractor, will use a large stationary gas turbine. A significant achievement in the vehicular turbine project was the successful engine test, 175 hours at 1930 F, of a silicon nitride stator. Durability testing on a nose cone was extended to 246 hours, equalling the previously demonstrated durability of 245 hours on 1st and 2nd stage rotor tip shrouds. A 'Refel' silicon carbide combustor previously demonstrated 171 hours durability, crack-free, including 20 hours at 2500F. Two additional combustors of the same material were tested for 10 hours each. Eight hours of testing the stationary ceramic flowpath at 2500 F were accumulated; non-catastrophic cracks occurred in the nosecone and stator after surviving three hours crack-free. Two stator vanes survived 1000 cycles to 2500-2600 F plus 3720 cycles to 2900 F in the thermal shock rig. A concentrated effort on turbine rotor fabrication development was initiated. Improvements in the rotor fabrication processes have been made. Reduction of the MgO content increased the hot strength of the hot-pressed silicon nitride rotor hub material. Over 500 rotor blade rings were fabricated using the injection molding process and some high density rotor blade rings were also fabricated by slip-casting.