Copper plating aluminum for increased heat conductivity
Quickstart:
There are 3 modes of heat transfer: conduction, convection, & radiation.
1. Conduction is heat transfer through solid materials; many solids, including metals, conduct heat very effectively, as we learn by touching hot objects and burning ourselves the instant that a solid-to-solid connection is established.
2. Convection is heat transferred by air, such as the heating of the air in a room by a hot water radiator.
3. Radiation is heat transferred by infrared waves, even across a vacuum, like the heating of the earth by the sun. Radiation is a tiny factor at low temperatures, but a big factor at very high temperatures; that little disk in the sky warms the whole planet from millions of miles away, but its temperature is millions of degrees.
Sometimes heat transfer is by more than one of the methods. A hot campfire warms us primarily by radiation, but a shift in the wind may singe our hair as the convected heat washes over us.
Q. I am looking to increase the heat conductivity of aluminum by copper plating. Is there any data to show this will work?
Jeff "Fuzzy" Horton end user - Troutman, North Carolina, USA November 3, 2009
A. Hi, Fuzzy. The thermal conductivity of copper is about twice that of aluminum, but that doesn't mean your application will "work". Readers would need particulars to be able to assist you.
Regards,
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey
Q. Ted,
If I copper coated an aluminum heat sink being used to cool a component via the air flow across the heat sink would it cool the component better?
Regards,
Jeff "Fuzzy" Horton [returning] end user - Troutman, North Carolina, USA
A. No, it wouldn't. Sorry. The conductivity of a metal has such little effect on convection that it isn't even included in the formulas for estimating convective heat transfer. Improving the air flow is the way to go. Good luck.
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey
Q. Hi Ted, I am trying to figure out a very similar combination. But let me rephrase the original question Jeff had:
Would copper plating of aluminum heat-sink increase heat transfer from the bottom to the top, which in turn would make fins warm up (absorb heat) faster/better? And given the same air flow would keep bottom surface slightly cooler.
So example would be: aluminum heat-sink 50 x 50 x 50 mm.
If we copper plate the entire object, would it help heat travel twice as fast bottom to top through copper layer, and then in turn transfer heat more uniformly to underlying aluminum (while air cooled)? Or thin layer of copper wouldn't be of any significance to sustain heat transfer benefit?
One other example is copper blocks are often embedded into aluminum heat-sinks, which helps withdraw heat faster, or heat pipes, which transfer heat at much higher rate.
Thanks Ted!
Roma Zhevin - Staten Island, New York, USA November 12, 2009
A. Hi, Roma. A chain is only as strong as its weakest link, and that includes heat transfer chains. Although we haven't talked about sizes, orientations, etc., I am pretty confident that both of you will find the convection element to be by far the weak link in the chain, because it invariably is, such that any effort you put into increasing the conductivity of the metal will be wasted as roundoff error.
While you could get a heat transfer book from the library and work the calculations, and I encourage it, simple experience can guide you as well: If there is a hot pan on the stove, you will burn yourself if you touch it regardless of what the pan is made of. The reason we accidentally touch hot pans is that the convective and radiative heat transfer from the pan to our hand is so low that we get almost no warning as our hand approaches it.
I think the reason copper blocks are used in water cooled heat sinks is that copper is a much better water piping material than aluminum. Best of luck.
Regards,
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey November 12, 2009
Thanks Ted, your input is greatly appreciated!
Roma Zhevin [returning] - Staten Island, New York, USA November 14, 2009
April 12, 2013
Q. Dear Ted,
I agree with your above answer.
I wanted to know your opinion about the following scenario:
I was just analyzing thermal conductivity of plated metal plates and goal is kind of opposite.
That is, when a thick (5 mm) metal plate of high thermal conductivity like aluminium is plated on top with a very thin layer of another metal like nickel having "low thermal conductivity" (I put it in quotes because it is mentioned in standard units W m^-1 K^-1).
When we calculate amount of heat conducted by 5 mm aluminium we may find that it is <= amount of heat conducted by 5 µm thick metal layer of low thermal conductivity like nickel, steel, tin, etc. That way maybe thermal conductivity of plated aluminium plate should remain equal to aluminium plate.
My apologies if I am wrong. I am not from metallurgy field. I just got interested in this because one of my requirement for plating (which still remains unfinished).
Regards,
Ravi
Ravi Gautam - Mumbai, Maharashtra, India
A. Hi Ravi. This is a public forum where readers post their questions and other readers try to help answer them. As the website operator, I try to keep the discussions moving along by trying to answer if no one else has . . . but that doesn't mean I fancy myself a heat transfer expert; I'm not.
Still, in order to not derail the readers, we should probably warn them that you are talking about conduction whereas I was talking about convection.
I am perhaps not understanding your question correctly, but if your question is why a 5 µm layer of "low conductivity" nickel seems to be a smaller impediment to heat transfer than a 5 mm thickness of aluminum, well, it's a thousand times as thin, whereas the thermal conductivity of metals varies by a factor of about ten, not a thousand.
Regards,
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey April 12, 2013
April 15, 2013
Dear Ted,
Thank you very much for your reply. Not many forums helps people with their queries as much as this forum.
Q. Actually I wanted to be sure that I am not thinking in wrong direction about applying nickel plating on 5 mm thick aluminium skillet.
Yet I am not sure how much life I should expect from it. Advice about any alternative or find out a way about "do it at home" will be appreciated. Actually I am finding it difficult to find somebody who can do the plating work for me.
Regards,
Ravi
Ravi Gautam [returning] - Mumbai, Maharashtra, India.
A. Thanks Ravi. Please search the site for "nickel plating at home" and post on one of those threads. We want to help you, but we have 60,000 topics, and if threads about the thermal advantages of industrial copper plating of heat sinks wander off into the anticipated service life of D-I-Y nickel plating of aluminum pots, and then on into the subject of which are the better nickel plating shops in Mumbai, readers will be unable to find anything :-)
Regards,
Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey April 15, 2013
Conductivity coatings for heat sinks
Q. Sir,
I observed from journal papers that performance of heat sink is improved by thermal conductivity coatings on substrate. Is it wrong? Why increasing the thermal conductivity, not increasing the heat transfer?
SREEDAHR VULLOJU Vardhaman College of Engineering - Hyderabad,Telangana, India July 8, 2017
? Hi Shreedahr. Sorry, but I don't understand what you are saying or asking. Please try to offer specifics regarding what you did and what the results were. What coating did you apply. What did you measure and discover? What was the temperature -- was it high enough that radiative heat transfer may play a part? What exactly did the journal article say that disagreed with your findings? Talking in the abstract about 'conductivity coatings' on heat sinks which rely on convection and possibly radiation rather than conductivity seems to lead only to additional misunderstandings rather than greater clarity :-)
Thanks, and Regards,
Ted Mooney, P.E. RET Striving to live Aloha finishing.com - Pine Beach, New Jersey July 2017
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Thanks Ted, your input is greatly appreciated!