Osamu Funayama

Fabrication and pressure testing of a gas-turbine component manufactured by a preceramic-polymer-impregnation method

Abstract One of the components of the gas-turbine engine, the inner scroll support, was fabricated by a SiCO-fiber-reinforced SiNC composite of which the matrix was obtained from methylhydrosilazane. The part was shaped by laminating prepreg sheets, consisting of SiCO fiber cloth and methylhydrosilazane, and cured by using a vacuum-bagging method. Densification of the product was performed by polymer impregnation and pyrolysis (PIP). The fracture strength and stress/strain behaviour were measured by the use of a hydraulic internal pressurization test. Hysteresis during cyclic loading and pseudo-elastic behavior were observed in the composite component. Thus behaviour was similar to that found in mechanical tests of small specimens. The fracture strength of the composite part was estimated to be 180 MPa, which was the same as the tensile strengths of test pieces.

Mechanical properties and oxidation resistance of C–B–Si coated silicon nitride fiber reinforced Si–N–C composites with cross-ply structure

To enhance the oxidation resistance of a ceramic matrix composite, a C-B-Si interface layer was applied between the fiber and the matrix. The layer was deposited on the fiber by chemical vapor deposition. Three types of coatings were prepared: A1, A2 (multilayers of graphite layer/B-C-Si crystalline layer/graphite layer) and B 1 (monolayer of B and C containing graphite). The multilayer coated CMC retained 88-97% of the original strengths after oxidation at 1523 K for 36 ks. The monolayer coated CMC degraded to 55% of its original strength after oxidation, but had a high fracture toughness (28 MPa m 1/2 ) before oxidation. The differences of the oxidation resistance and fracture toughness were discussed in relation to the microstructure of the coatings.