Surface Finish and Notch Effect Model for Strength Predictions of Continuous Fiber Ceramic Composites (CFCCs)

2008 ◽  
pp. 160-160-12
Author(s):  
M Ramulu ◽  
MG Jenkins ◽  
S Kunaporn
Keyword(s):  
Surface Finish ◽  
Ceramic Composites ◽  
Notch Effect ◽  
Continuous Fiber ◽  
Effect Model

Surface and Subsurface Study on EDG and EDM Processing of Advanced Ceramic Composite Material

2013 ◽  
Author(s):  
M. K. Satyarthi ◽  
Pulak M. Pandey
Keyword(s):  
Ceramic Material ◽  
Electric Discharge ◽  
Surface Finish ◽  
Ceramic Composite ◽  
Ceramic Composites ◽  
Recast Layer ◽  
Machining Processes ◽  
Workpiece Material ◽  
Advanced Ceramic ◽  
Subsurface Cracks

The advanced ceramic composites are made electrically conductive by doping with the conductive phase elements like TiN, TiC, TiB2 and TiCN. The doping of the naturally occurring nonconductive ceramic composite makes it suitable to be machined by unconventional machining processes where conductivity of the material plays prominent role. Though, the ceramic materials are fragile in nature, these are custom-tailored for the engineering applications. The machining of the ceramic material by conventional processes is quite difficult and leads to failure of the material under high cutting forces due to its fragile nature. In most of the cases deformities like surface and subsurface cracks, inclusion of pits and voids, deteriorates the functionality of the ceramic material. In our work, we have studied the surface and subsurface characteristics, while processing the material by electric discharge machining (EDM) and electric discharge grinding (EDG) processes. A setup has been designed, developed and mounted as an attachment on die-sinking EDM machining facility to carry out the EDG experiments. The conductive alumina ceramic has been chosen as workpiece material for processing. The surface characteristics has been observed by scanning electron microscopy (SEM) at the resolution of 1000X for EDG processed work pieces, and at 500X for EDM. In EDM machining, the surface contains the recast layer whereas in EDG, the recast layer is either removed or swept uniformly along the surface giving good glossy surface finish. It has been found that the components produced by EDM process contain prominent surface and subsurface cracks whereas such deformities are not visible in case of EDG processing. The best surface finish achieved is of the order of 0.04μm when processed by EDG.

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.

Sign in / Sign up

Export Citation Format

Share Document