Looking for etched metal specimens

Chris,

Have you tried asking at a local university that does Mech Eng or similar. We did polishing and etching of materials to examine the structure on my Mech Eng course, I would have thought others would be similar unless the powers that be have deemed it too dangerous playing with dilute acids these days.

Thanks for the suggestion. I've asked a friend of mine who's doing a PhD in materials science, but he said he's mostly on the theoretical side and rarely sees samples. A local university is a possibility I guess, but we're a bit short on them here in Shropshire. I wouldn't mind etching my own, but it's a bit hard to get hold of the concentrated nitric acid need to make the etching solution. I might try posting this on uk.rec.models.engineering and see if anyone has further ideas.

Best wishes,

Chris

...follow-up...

Look at

-- JR

Nup. A plain old reflecting microscope will keep you entertained for hours. It all hinges on good polishing and etching, of course. These 'scopes always have (and need!) built-in lighting, which operates axially.

I don't even know what a phase-contrast microscope *is* ! :-(

If it does what it sound like it does, then it would be great - yes - but not necessary.

I've gone up to pretty impressive magnification(s) with the oil-immersion lens, too.

Sigghhhh... Memories.

-- Jeff R.

I ought to be able to lay my hands on dilute nitric acid, but it's diluted in water. My understanding is that the etch needs to be made from nitric acid in ethanol or methylated spirit. There's also apparently some reason why you shouldn't store the etch either.

What the effect of trying to etch specimens in dilute nitric acid would be, I don't know. Would they go rusty? If it works, that would be neat, because dilute nitric acid is far easier to source.

See my latest thread on microscopes.

Best wishes,

Chris

Thanks for that link!

Best wishes,

Chris

Now I really want to know what you are planing to do with them together with the microscope ...

Nick

Take photographs. If you want to know what I'm going to do with the photographs, I'll announce it at RCM in the future, but I'm not quite ready yet.

Best wishes,

Chris

Of course. You aren't going to get much illumination through the metalfrom below. :-)

It combines light through two paths which results in colors derived from *very* slight differences in height.

I would be interested to see what a difference it makes with polished and etched metal samples. I've only used it on integrated circuit dice.

O.K. That sounds good enough.

I can't seem to find any connection of phase contrast with metalurgical with a quick Google search.

Enjoy, DoN.

----- Original Message ----- From: "Christopher Tidy" Newsgroups: rec.crafts.metalworking Sent: Friday, January 25, 2008 8:44 AM Subject: Re: Looking for etched metal specimens

I admit I'm guessing here, but I don't see (much of) a problem with the dilute option. The specimen is dried immediately after etching, and remains in a dry case. I don't think rust would be a problem. Anyways - etching duration is always a moveable feast, regardless of Nital concentration.

I've spent many an afternoon etching then re-lapping then etching, then etching again, then re-lapping again (repeat ad infinitum).

Wilco.

-- Jeff R.