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Posted by Christopher Tidy on January 26, 2008, 11:53 pm
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Cheshire Steve wrote:
<snip>
> You realise you need a metallurgical microscope - i.e. one which
> illuminates from above. The majority of microscopes illuminate from
> below.
Yes I do. I'm thinking of buying one. I'm just researching the
practicalities of it before I do.
> You don't say why you want to do this - are you teaching yourself
> metallurgy, or hoping to provide a technical service ? Its an
> interesting area, and a lot of science goes into understanding what
> you see. I can recommend a good book if you are interested.
Two reasons. Firstly for fun and to learn something. Secondly because
I'm building a website about engineering design and therefore want a few
pictures of the microstructures of common metals.
Best wishes,
Chris
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Posted by Cheshire Steve on January 27, 2008, 6:20 am
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> Cheshire Steve wrote:
>
> <snip>
>
> > You realise you need a metallurgical microscope - i.e. one which
> > illuminates from above. The majority of microscopes illuminate from
> > below.
>
> Yes I do. I'm thinking of buying one. I'm just researching the
> practicalities of it before I do.
>
> > You don't say why you want to do this - are you teaching yourself
> > metallurgy, or hoping to provide a technical service ? Its an
> > interesting area, and a lot of science goes into understanding what
> > you see. I can recommend a good book if you are interested.
>
> Two reasons. Firstly for fun and to learn something. Secondly because
> I'm building a website about engineering design and therefore want a few
> pictures of the microstructures of common metals.
>
> Best wishes,
>
> Chris
Chris,
I qualified as a metallurgist, but my work has taken me away from that
now, but I have a hankering to get the capability back, and have
slowly acquired a small furnace, microscope, and hardness tester (its
wonderful what you can pick up on ebay). One thing I don't have is the
arrangements for mounting and polishing specimens. You might get away
without mounting, but you need to be able to get a good flat polish on
the surface before etching. Normally successively finer water washed
emery papers, then if I remember correctly we used 6micron and then 1
micron diamond paste on a rotating table a bit like a record deck, but
with more grunt. Steel etching is a fairly quick affair with 5% nitric
in ethanol (referred to as Nital), or maybe 10%. Different etchants
could be used for other metals.
The core of metallurgy is understanding how heat treatment changes the
microstructure of metals and hence modifies the properties, and
understanding this means understanding the phase diagrams which show
the solid state transformations, and then understanding how changing
the cooling rate changes the microstructure. Much of the rest of
metallurgy overlaps with other disciplines, for example fatigue
failure, crack growth, overlap with mech eng; corrosion, plating,
extraction, refining, overlap with chem eng; and ores and minerals
overlaps with geology. For my money the best book I have seen on this
'core' aspect is Metallography of Phase Transformations by Chadwick,
it really links the phase diagrams to the microstructure. I still have
my copy as well as my notes from the lectures back in the 1970s - so
if you want me to look some things up then drop me a line. I may even
have some microstructure photos, though generally we drew them by hand
- that way the significant features had to be appreciated by the brain
cells. It reminds me of the quote that lecturing is the art of
transferring information from the notes of the lecturer to the notes
of the student without passing through the minds of either - it is of
course not true!
Best of luck.
Steve
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Posted by Adrian Godwin on January 28, 2008, 10:29 am
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> wonderful what you can pick up on ebay). One thing I don't have is the
> arrangements for mounting and polishing specimens. You might get away
> without mounting, but you need to be able to get a good flat polish on
> the surface before etching. Normally successively finer water washed
> emery papers, then if I remember correctly we used 6micron and then 1
> micron diamond paste on a rotating table a bit like a record deck, but
I have a metallurgist's "belt sander" - it has a much superior
belt-tracking arrangement than the usual hardware-store version,
facilities for keeping the sample and belt wet, and a wash sump.
It's a bit bulky, though - I'd swap it for a more ordinary linisher
as long as it had reasonable belt control.
-adrian
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Posted by Christopher Tidy on January 29, 2008, 2:26 am
Please log in for more thread options Adrian Godwin wrote:
>
>
>>wonderful what you can pick up on ebay). One thing I don't have is the
>>arrangements for mounting and polishing specimens. You might get away
>>without mounting, but you need to be able to get a good flat polish on
>>the surface before etching. Normally successively finer water washed
>>emery papers, then if I remember correctly we used 6micron and then 1
>>micron diamond paste on a rotating table a bit like a record deck, but
>
>
> I have a metallurgist's "belt sander" - it has a much superior
> belt-tracking arrangement than the usual hardware-store version,
> facilities for keeping the sample and belt wet, and a wash sump.
>
> It's a bit bulky, though - I'd swap it for a more ordinary linisher
> as long as it had reasonable belt control.
Thanks for the offer. I don't have a linisher around to swap for it, though.
Just out of interest, what make and model is it? I might look out for a
similar one.
Best wishes,
Chris
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Posted by Adrian Godwin on January 29, 2008, 3:18 pm
Please log in for more thread options > Adrian Godwin wrote:
>>
>>
>>>wonderful what you can pick up on ebay). One thing I don't have is the
>>>arrangements for mounting and polishing specimens. You might get away
>>>without mounting, but you need to be able to get a good flat polish on
>>>the surface before etching. Normally successively finer water washed
>>>emery papers, then if I remember correctly we used 6micron and then 1
>>>micron diamond paste on a rotating table a bit like a record deck, but
>>
>>
>> I have a metallurgist's "belt sander" - it has a much superior
>> belt-tracking arrangement than the usual hardware-store version,
>> facilities for keeping the sample and belt wet, and a wash sump.
>>
>> It's a bit bulky, though - I'd swap it for a more ordinary linisher
>> as long as it had reasonable belt control.
>
> Thanks for the offer. I don't have a linisher around to swap for it, though.
>
> Just out of interest, what make and model is it? I might look out for a
> similar one.
>
It's a Metaserv C1850A (read off the plate - I have no idea if that's good
or bad!). Here's a picture :
http://www.flickr.com/photos/23312780@N04/2228532703/
I was planning to strip it down and use the mechanism to make something
more suited to my needs, but it seems a shame if someone needs it as-is.
I'm sure we could come to some arrangement if you or Steve want it.
I notice there's also some sort of diamond grinder on ebay - maybe
this would do for finishing ? Needs a bit of work ..
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260205896898
-adrian
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> illuminates from above. The majority of microscopes illuminate from
> below.