Glass, Ceramics, Fibers & Fabrics

My understanding of ceramics is certainly not a strong point with me..............so I ask the question, "Are ceramic materials manufactured today capable of withstanding mechanical shock?" ............thermal shock probably OK??

I know that many years ago, experiments were conducted with ceramic blading in gas turbines and were not terribly successful because of failures due mainly to mechanical shock. The same thing applies when using ceramic tipped tools in various machining operations..........could not be used with any interrupted cutting, e.g. spline, slot, keyway, etc.

All I ask is have things changed????

low-pressure third-stage blades can even be made from ceramic matrix composites

I think you answered your own question in the statement above by indicating that currently even a stage 3 blade in the low pressure section requires cermet composite .....but never say never when good old cash is a stake.

"Iceberg"....I mean "GEESE...dead-a-head"

I think we've tried to build the ceramic gas turbine (DOE's program with Ford Motor Company lasted years). We tried to build the ceramic diesel engine. And the shuttle Columbia was a ceramic space/aircraft. We've never found the 'universal' material problem (non-corrosive, strong, malleable, lightweight, etc. etc.). Everything is a compromise.

Whatever happened to cermets?

They were supposed to solve both thermal and mechanical shock problems of ceramics as well as allowing significant increases in turbine temperatures and hence overall efficiency.

What were the insoluble problems which made them eventually no use?

Current work seems to be concentrated on ceramic fibre reinforced ceramics, rather than the metal reinforcement of cermets.

I know they had problems with lack of cohesion between metal fibres and ceramic, but plating the fibres with Si looked as though it would lead to a solution there.

Does anyone know what else happened to apparently knock cermets out of the running?