If you wanted a filler for JB Weld, or Arctic Alumina adhesive, (for use as a heat sink), which one below would you use?
In Powdered Form:
Copper
Aluminum
Graphite
Carbon
Diamond
And... anyone really know which is way above the others? Since they are all power and would all be used as a filler, so it's not like a solid object. Is it a mute point?
Wouldn’t copper or aluminum make it electrically conductive?
Edit: Are you heat sinking, as in a pill, or are you heat sinking (potting) a driver?
The only two I've ever used are Al powder (made myself by filing a scrap piece of Al) and SiC, not sure which worked better.
If the light was for a girl and you really liked her I'd suggest diamond. Ok l'll run away now.
TP will have the correct answer.
If I remember my Physics correctly Diamond would be the best thermal conductor and electrical insulator.
Tumbling Grit-400 Fine-Silicon Carbide
http://www.ebay.com/itm/141274305419?ssPageName=STRK:MEWNX:IT&\_trksid=p3984.m1497.l2649
This is what I use, six and a half bucks for a half pound. I mix it with JB weld Industro for potting. I don’t have any numbers but it does seem to really do the trick. I know that my protected drivers will shut down without it and with it they are generally fine.
Is the green silicone carbide also good for potting?
silicon carbide:
global.kyocera.com › HOME › Characteristics of Fine Ceramics
Thermal: heat conductivity. … Fine Ceramics Offer a Wide Range of Thermal Conductivity … Aluminum nitride and silicon carbide transfer heat particularly well….
Here is a chart with a few of them on it.
Silicon Carbide 200
Aluminum Nitride 150
Aluminum Nitride 41
Alumina <A479(99%Alumina)> 32
Alumina
Silicon Nitride 27
Also from what I have read, the hotter it gets the more conductive Silicon Carbide becomes.
Do you have your best combination ratio of the Silicon Carbide with the epoxy?
I really have no idea what is the “best” but I mix an even ratio of each so I just put out a pile of each of the epoxies and another matching one of the Carbide. So roughly 30%.
Gotta be quick with it though.
I would use it for heatsinking, but not for potting a driver. I am thinking of lights where trying to make a heat sink is a pain and after the T08 deal, I see how easy it is to mold one right in the light, as long as the surfaces are waxed first. So, I am not worried about electrical conductivity, just the best thermal transfer.
If only we had little heat pipes handy, so the heat could be pulled out of the flashlight to some kind of collar from which it could go away. Here’s a comparison between a solid metal rod and a heat pipe:
http://www.waermeleitrohre.de/eng/wlr049.htm
It’s been talked about a lot, one way or another:
https://www.google.com/search?q=“heat+pipe”+flashlight
Not sure if any epoxy mix will replace even a brass sink but it would be better than nothing.
yeah…actually Silicon RTV is a better heat conductor than epoxy
Good info, got details?
EDIT: see post #17
Depends on the epoxy. Arctic Silver and Arctic Alumina are better heat conductors than RTV. RTV is somewhere around 1.5 to 1.8 W/m.K I think Arctic Silver is about 8.5 W/m.K and I don’t remember what Arctic Alumina is. So, RTV isn’t better than those epoxy compounds, but maybe better than regular epoxy.
Point is, if any of it were mixed with a high ratio of Copper or Diamond dust, it should increase thermal transfer.
Epoxy 0.35
Silicone cast resin 0.15 - 0.32
I stand corrected
Thanks for the update. Bottom line is that they are both terrible compared to metals… but also an order of magnitude better than air. For those who aren’t sure what that means, they are both about 10x more thermally conductive than free air. Actually 14x or so at the high end.
Adding the things OL asked about in the original post seems to improve things further.
alumina
since that’s what arctic uses
its super cheap
and you can polish with it