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Water Block Design / Construction Building your own block? Need info on designing one? Heres where to do it |
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#76 | |
Cooling Savant
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#77 | |
Cooling Savant
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So the difference may not be huge, but it will make a slight difference, and with the level we've managed to get blocks down to now, it's gonna be that much harder to improve the C/W. Plus it's intellectually stimulating tossing these ideas around. Isn't that what people do around here, toss ideas round. 8-ball
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#78 | |
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Like yourself I have no data. J.M.(aka Les) Round (BSc, Phd, - Metallurgy, Leeds(1963 -69) - Mentor P.M.Kelly) |
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#79 |
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Indeed Dave.
I was hoping to remind the main participants that if there's a resulting application, it ought to be outlined in such a way so that one can understand the purpose of it: I think we lost Hara a couple days back. I understand the concept of the crystaline structures within the copper, and I can somewhat follow how a certain process may yield an improvement, but I do indeed need to understand better the extent of the potential improvement, as it applies to a waterblock. Sometimes I'll state something that I know is incorrect, to sollicit an answer (to BillA's great frustration ![]() For those interested in this topic, but not able to get too deep in it, I'd recomend an old pocket book that I found most interesting: "The new science of strong materials", by J. E. Gordon (mostly about structure, not about conductivity). |
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#80 | |
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That book got me through my first year exams That said, it still depends largely on the degree of cold working which provides the driving force for recrystallisation. Remember, we do have data for the difference in electrical conductivity for cold drawn copper and soft copper, a difference of just over 10%. Greater stored energy due to cold working will provide a greater drving force for recrystallisation, increasing the nucleation rate, resulting in a finer microstructure, which would probably not have as high a conductivity as a similar sample recrystallised from a lower state of cold working. 8-ball
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#81 | |
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Last edited by Les; 08-03-2003 at 08:59 PM. |
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#82 | |
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8-ball
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#83 |
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8-Ball
I think your quote is a misrepresentation. "Neither of which are particularly relevant to thermal conductivity and low temp strees relieving." (Pasted - including spelling mistake) |
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#84 |
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elaborate?
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#85 | |
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Two values(10% and 2%) for differences in Electrical Conductivity between an "undefined annealed condition" and a hard drawn conditions. I, perhaps mistakenly, take the annealed condition to be a Soft Anneal* which is several hundred degrees above the recrystallization temperature. I am not sure how one can relate this conflicting data in ,possibly, the Soft Annealed Condition to stress relieving at the suggested temperaures of 100C or 140C. * As defined here http://www.key-to-metals.com/ViewArticle.asp?ID=25 |
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#86 |
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"the annealed condition to be a Soft Anneal* which is several hundred degrees above the recrystallization temperature"
while I was but a simple lecturer at a Uni, this too is my understanding of it |
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#87 |
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I see your point.
8-ball
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#88 |
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@Bigben2k
Could you log on to yahoo messenger or contact me regarding a radial waterblock design Thnx ![]()
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#89 |
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pm = private message.
probably more appropriate.
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#90 |
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Here is a data sheet ( http://216.239.57.104/search?q=cache...C10200.asp</a> ) for the alloy of my block ("C10200 has conductivity 101% IACS, the highest among coppers."). This suggests 700-1400F for annealing. Since my block has skived fins, the conductivity gains should be good. Also, since I am working with a 300+ Watt heat flux (TEC), even a .01 C/W improvement will result in a CPU several degrees cooler.
My proposed process: 1. Lap on .000150" flat calibrated granite (400, 600, 1000 grit) 2. Anneal to 1400F in argon 3. Quench in water (my research indicates method of quenching makes no difference with Cu, water is fastest) 4. Lap on granite (1000, 1500, 2000 grit) Any suggestions? |
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#91 |
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no
as I understand grain size, NOT quenching is the key let it cool as slowly as possible you are after larger grain size don't waste your time lapping it before annealing, it will 'move' some info http://www.key-to-metals.com/ViewArticle.asp?ID=25 http://innovations.copper.org/metall...etallurgy.html http://www.completemetalworks.com/defs%5Cdefq.html (see second item - ??, not sure I agree) http://www.asia.copper.org/acic/faqs_body.html from above "What effect does heavy cold working have on the electrical conductivity of copper? It reduces by about 3%." http://www.public.asu.edu/~jtsasu/ece350/Topic6.htm "Excess vacancies may be introduced by quenching from high temperature, mechanical deformation, neutron irradiation." a 3% change in conductivity is going to be a bit difficult to measure |
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#92 |
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Thank you for the links. I decided to look a little deeper into the role of quenching on defects, and found more supporting evidence:
http://www2.umist.ac.uk/material/res...u/al4cu01t.htm "Rapid quenching also preserves the large number density of vacancies in the aluminium lattice from the high solution temperature." -edit: Not really relevant since the alloy is Al2Cu. So it appears I will be lapping the block just enough to remove any impurities (oil, dirt), then annealing (is it correct to use the highest temp in the annealing range?), then fine lapping. Last edited by koslov; 08-03-2003 at 10:54 PM. |
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#93 |
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yea, go for the high temp
you g:oing to test before and after ? (hopefully with enough mountings to understand the variance) |
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#94 |
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Sorry, my Digitec 5810 broke a few weeks ago, and I have yet to find an affordable replacement. So I have no means of accurate testing.
I annealed the copper for about 1hr at 1400F, and it came out red hot. Unfortunately, it quickly became covered in carbon as it cooled in the open air; the block was jet black (at least, I think the ambient air was the source of carbon, because the container was filled with argon during heating). And the base definitely deformed a bit: there are some tiny bumps where the copper seeped into the pores of the ceramic plate. Should I measure electrical conductivity with an ohmmeter and identical strips of annealed and hard-drawn copper? Then I can simply use the Wiedemann-Franz Ratio to compute thermal conductivity. |
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#95 |
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Since87 probably is a better source than I
no problem re the conversion, the experimental part is tough have you calculated how small the difference will be in ohms ? -> you have an 8 1/2 digit ohmmeter ? |
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#96 | |
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Well, then I truly have no way of measuring the annealing effect on conductance. What I am more interested in, though, is the effect on hardness. A reduction in Rockwell hardness from 54-62 to 47-57 seems worthwhile. Have any links relating material hardness to contact heat transfer? OT: How do they measure resistance for conductors? Using very long, thin filaments? Last edited by koslov; 08-04-2003 at 07:26 PM. |
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#97 |
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The waterblock being covered with carbon seems odd to me. Atmospheric CO2 breaking down due to high temperatures but then the carbon doesn't burn off again as the piece cools? Perhaps the black material is some component of the copper alloy that oxidized? I'd be concerned that the mass of the material, or composition of the alloy might have changed enough to skew results. It would be better to allow the test piece to cool in the Argon to prevent this.
Also, heating the copper to the point that it flows could skew results due to changes in resistance resulting from thinning or thickening the copper in spots. I could probably measure the resistance of a White Water baseplate to about 1% accuracy, but most waterblocks would be too thick for me to get a useful measurement. It's much easier to measure the resistance of a reasonably thin, long wire, but it would be easy enough (for me) to measure the resistance of something like a 4" X 0.5" X 0.05" strip with 0.25" long slots cut into each end of the strip. (The slots in the ends are to provide 4 connection points. Two for connecting a current source and two for connecting a voltmeter.) If you want to send me a strip like this, of the alloy you are using, I will measure the resistance of it, and send it back. You can anneal it and send it back to me, and I'll measure the resistance again. Alternatively, I can send you a strip of copper and you can anneal it and send it back, but what I have available is some ultra pure oxygen free copper that won't necessarily reflect the behavior of your alloy. Also, the stuff I have is already annealed, so I will have to bend it, pound it with a hammer, whatever, to get it hardened. (I don't know exactly what the stuff I can get is. It was imported from Japan for some hare-brained scheme by a former coworker.) |
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#98 |
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The C102 alloy in my block is 99.95% pure copper (http://www.fiskalloy.com/w-alloys-pa...opc102110.html). I actually do not know the alloy of my cold plate, but it is probably high copper since it was a cutoff from an EDM electrode.
Since87, if your copper is already annealed, why not test it, then pound and bend it, and test it again? I wouldn't know how to make a strip that small, and I don't have any work-hardened C102 left. |
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#99 |
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Not carbon, theres too little in the air to have any impact. Its probably just copper oxide, a little thicker then usual due to temp.
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#100 | |
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I decided to test the easy way instead. I took about six foot of 22 gauge magnet wire, put an Amp through it with a current source, and measured the voltage across it. I then wrapped the wire around a pencil and unwrapped it about 5 times to work harden it, and measured the voltage drop again. The resistance of the work hardened wire was 107.0% of the resistance of the unworked wire. Some of the increase of resistance may have been due to a bit of stretching of the wire as I wrapped it, but I'd guess that was under 1%. (Can't measure a change in length, since the worked wire is all kinked up.) I think the most accurate and useful test would start by measuring the resistance of a hard piece and then annealing. This would minimize any mechanical changes to the piece. I do think the test I did, indicates that a gain of significantly more than 3% in conductivity may be attainable through annealing. |
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