scholarly journals Research and development of material/processing methods for the Continuous Fiber Ceramic Composites Program. Monthly report, July 1994

1994 ◽  
Author(s):  
A. Szweda
Keyword(s):  
Material Processing ◽  
Research And Development ◽  
Ceramic Composites ◽  
Continuous Fiber ◽  
Monthly Report ◽  
Processing Methods

Methods of Improving Glow-Discharge-Deposited a-Si1−xGex:H

1991 ◽  
Vol 219 ◽  
Author(s):  
Y. S. Tsuo ◽  
Y. Xu ◽  
E. A. Ramsay ◽  
R. S. Crandall ◽  
S. J. Salomon ◽  
...  
Keyword(s):  
Material Processing ◽  
Glow Discharge ◽  
Substrate Temperature ◽  
Gas Mixtures ◽  
Gas Composition ◽  
Processing Methods ◽  
Helium 4 ◽  
Process Gas

ABSTRACTWe have studied methods of improving glow-discharge-deposited a-Si1−x Gex :H alloys deposited using silane and germane gas mixtures. Material processing methods studied include (1) varying the substrate temperature from 170° to 280°C, (2) varying the process gas composition and pressure, (3) dilution of the feed gas by hydrogen, argon, or helium, (4) enhancing etching during deposition by adding small amounts of XeF2 vapor into the process gas, and (5) postdeposition annealing and/or hydrogenation.

scholarly journals Applications of Continuous Fiber Reinforced Ceramic Composites in Military Turbojet Engines

1996 ◽  
Author(s):  
Patrick Spriet ◽  
Georges Habarou
Keyword(s):  
Weight Ratio ◽  
Ceramic Matrix Composites ◽  
Thermodynamic Cycle ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Continuous Fiber ◽  
Operating Life ◽  
Performance Improvements ◽  
Temperature Capability

Over the last twenty years, significant performance improvements of turbojet engines have been achieved by optimizing engine thermodynamic cycle along with the introduction of new materials providing higher temperature capability and weight reduction. Metal Matrix Composites (MMC) and Ceramic Matrix Composites (CMC) are candidate material systems to meet the required thrust-to-weight ratio of 15 or higher. Continuous fiber reinforced ceramic composites, which have been developed by SEP for more than 15 years for thermostructural applications in oxidative environment, aim at increased operating temperature over superalloys and intermetallic alloys. This paper is a review of the main CMC component demonstrations performed by SEP over the last 10 years for turbojet engines along with an analysis of consequences on materials development and design methodology. The development status of a new thermostructural material specifically developed for turbojet environment with the prospect of higher design stress allowables and longer operating life at high temperature is presented.

Burner Rig Thermal Fatigue Failure of SiC Continuous Fiber/Si3N4 Ceramic Composites

1994 ◽  
Vol 365 ◽  
Author(s):  
T. Ertürk ◽  
K. Park ◽  
C. Sung
Keyword(s):  
Fatigue Failure ◽  
Thermal Fatigue ◽  
Thermal Stresses ◽  
Ceramic Composites ◽  
Columnar Structure ◽  
Fatigue Properties ◽  
Continuous Fiber ◽  
Sic Fiber ◽  
Transmission Electron ◽  
Fiber Matrix

ABSTRACTThe burner rig thermal fatigue properties of SiC continuous fiber/Si3N4 ceramic composites were examined under impinged jet fuel flame, a constant applied tensile stress and thermal cycling in the temperature range 500-1350 °C. The SCS-9 SiC fiber/Si3N4 composites failed within the flame impinged zone, whereas the SCS-6 fiber/Si3N4 composites failed outside the flame impinged zone due to the high thermal stresses resulting from high-temperature gradients. Analytical transmission electron microscopy was used to investigate the microstructure and chemistry of the fiber, matrix and fiber/matrix interface in the failed SCS-9 SiC fiber/Si3N4 composites. The partial degradation of columnar structure of the fiber was interpreted as the dominant mechanism of burner rig thermal fatigue failure of SCS-9 SiC fiber/Si3N4 composites.

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