What frequencies range should be used to measure internal micro- crack of a metal rods , using SAM (scanning acoustic microscope) technique

[student85]

Hi guy, currently i doing research on SAM (scanning acoustic microscope technique) techniques to measure the internal micro-crack for material.

 

But now the problem i facing is, most of the reviews i found are using SAM technique to measure internal crack for IC chips. May i ask is SAM technique suitable for larger material, such as metal rod( length = 400 mm, diameter= 30mm)?

 

Next , i was researching on the suitable frequencies to measure the internal crack for the metal rod. The frequencies range is 10MHz to 2000MHZ. But i also found out when the frequency increase, the penetration ability will decrease. So may i ask, what is the suitable frequencies range to measure the internal mirco- crack for a metal rod which is length = 400 mm, diameter= 30mm.

 

Please kindly advice.

[Enthalpy]

Why shouldn't you ask the manufacturer of the equipment?

 

And: do you want to detect micro-cracks, or get an estimation of the size, or see their shape and exact position? Only the last option needs a wavelength shorter than the crack.

 

The English article at Wiki is useless, but the German one helps:

http://de.wikipedia.org/wiki/Akustische_Mikroskopie

GHz frequencies penetrate far less than 1mm in solids - they don't tell in which solid.

 

Anyway, if the only manufacturers target semiconductors, you can forget it.

[student85]

Hi Enthalpy, thanks for your reply.

 

Currently, i did not have the equipment in my hand, So i dont know which manufacturer should i ask.

 

And: I want to detect micro-cracks, see its shape, exact position and measure its length.

[student85]

By the way, i have another question.

 

What is the different between x-ray tomography and x-ray micro-tomography?

 

Is micro-tomography suitable to measure large material, example a metal rod ?

 

It is because the reviews that i have read up seem like both methods can measure large material. while micro-tomography seem like can measure smaller things compare with tomography.

 

Please kindly advice