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529 views
04:39 Apr-19-2002

Oliver Brunke

R & D
ZARM - University of Bremen,
Germany,
Joined Apr 2002
1
monitoring of liquid metal foams with non contact ultrasonics?

Hello everybody,

in the frame of a research project our aim is to monitor the density and porosity of liquid Aluminium-foams. For the foaming process the samples will be placed in cylindrical containers of approximately 25mm diameter in a furnace at Temperatures around 600-700°C.
We think about using non contact ultrasonic transducers for this purpose. What I'd like to know is if this might be principally possible and if yes what kind of companies I could contact for the transducer design.
Thanks in advance for any kind of help!

Oliver Brunke



 
05:15 Apr-19-2002

Joe Buckley, Sonatest Plc

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
515
Re: monitoring of liquid metal foams with non contact ultrasonics? Are you trying to monitor these while in the furnace?

We have done some work with metallic foams when cold, but doing it hot would be well outside our experience. I think that transducers would be a problem - Very high effciciency piezo materials are required for Non contact 'conventional' UT transducers, which tend to be incompatible with High temperature operation .

Laser UT methods may be feasible?

Good luck
Joe

: Hello everybody,
.
: in the frame of a research project our aim is to monitor the density and porosity of liquid Aluminium-foams. For the foaming process the samples will be placed in cylindrical containers of approximately 25mm diameter in a furnace at Temperatures around 600-700°C.
: We think about using non contact ultrasonic transducers for this purpose. What I'd like to know is if this might be principally possible and if yes what kind of companies I could contact for the transducer design.
: Thanks in advance for any kind of help!
.
: Oliver Brunke
.



 
05:49 Apr-19-2002
chris edwards
Re: monitoring of liquid metal foams with non contact ultrasonics? I have carried out non-contact ultrasound measurements on
partially molten/ fully liquid aluminium alloys using
laser generation and EMAT detection.
In the semi molten state the attenuation is very high but
when the metal is fully melted it the attenuation is very low
and the EMAT detector works efficiently.
One of the samples was made by an OSPREY process and contained a lot of trapped
gas. When melted under vacuum it caused the aluminium to form a foam
and it was not possible to detect any ultrasonic signals.

Laser generation, EMAT detection is possible at temperatures in excess
of 1000 C but it foams are very attenuative at ultrasonic frequencies.




 


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