[Diy_efi] This turbo assist stuff, suggestions

Jay Wallace wallkatt at netzero.com
Thu Jan 2 01:29:47 GMT 2003


For those who haven't completely tired of this thread...

I believe that the turbine blades in the 747 are not ceramic but are 
ceramic coated - thermal barrier coating consisting of zirconium oxide - 
yttrium oxide probably put on by physical vapor deposition. These coatings 
are classified as not prime reliant (or some such) meaning that if the 
coatings fail, the entire engine does not fail.

The auxiliary power unit in the 747 was rumored to be monolithic silicon 
nitride, as are automotive turbos.

Also, in a separate e-mail from Matt, it looks like the failure mechanism 
of the ceramic turbos was the connection from the monolithic hub / blade 
ceramic assembly to the metal shaft, not a catastrophic failure of the 
ceramic. Yes, I know that the turbo is dead at this point but, from an 
engineering point of view, this is a much different failure.

And, yes, if your are asking me, I don't think that I would like to fly 
in  a plane with prime reliant ceramic engine parts. Not just yet anyway.

Jay

At 08:51 03/01/02 +0800, you wrote:
>On Thu, Jan 02, 2003 at 03:34:54AM +0800, Mike wrote:
> > I might add, I have nothing in principle against the use of ceramic
> > wheels - with wide tolerance, in factory (conservative) applications,
> > I just feel more comfortable in those other circumstances with
> > something a little more old fashioned - dat silvery metal ;)
>
>IIRC, on a Boeing 747 the first stage turbine's blades are largely
>"ceramic".
>
>Ceramics ar more dimensionally-stable under high temperature.
>
>--
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