Anodizing – Real solution for an aluminum water block?
In principle, this is quite possible and Gigabyte has to be taken in its stride at least as far as the OEM / ODM has skimped a bit. If the aluminum blocks are made of suitable metal and cleanly processed as well as anodized and sealed, then this can definitely work out well. The first step, however, is to choose the right material, because pure aluminum is much too soft. The large contact pressures of the ampere chips alone quickly cause the manufacturer to flounder.
In order not to impair the cooling performance too much, the lowest possible coldplate thickness in the cooling channels is an important factor. And that’s where the problem begins, because you have to add other metals to make the material sufficiently strong or hard. If silicon is used, it is also permanently incorporated during anodizing. This is the ideal case, but unfortunately it is usually too expensive as a semi-finished product. It is more common to use magnesium or zinc for stabilization. But these are metals that are dissolved out again during anodizing and leave holes.
In general, therefore, a good anodized product requires a suitable starting material, a well-cleaned and as homogeneous as possible surface, as well as proper cleaning before anodizing and coating or at least boiling out the layer. And now let’s take a look at the coating, which I took with special lighting and a suitable angle and startle:
First, we see the extreme grooves that come from a very rough tool, you can get something like that much smoother. On the left, the block with the T belongs to the VRM heatsink and is not galvanically anodized, but it carries a normal, natural oxide layer. The right area is anodized, but appears significantly darker than the light area in the left third, where the final coating on the threaded hole is tearing open and was not executed homogeneously (defect).
And that’s exactly why we have to talk briefly about the manufacturing process after all. First, the surface must be mechanically cleaned of all burrs if possible (marked yellow in the picture below), then degreased and stained. This is done in a first step with an alkaline solution (e.g. sodium bicarbonate) and then with an acid (usually hydrofluoric acid or nitric acid). However, the hydrofluoric acid must also be completely removed again. The rather brownish color of the deposits could therefore also come from poor cleaning or indicate iron in the water circuit. Whereas in my case there was none. The upper side with the microchannels has been anything but cleanly manufactured and reworked, which favors the “docking” of corrosion products (orange marking).
Now comes the electrochemical treatment by anodic oxidation, which produces significantly stronger layers than natural oxidation…. In this process, the aluminum is anodized in suitable acid (electrolyte) by means of direct current. The oxygen produced at the aluminum surface now reacts superficially with the metal and the desired aluminum oxide is formed. And now comes the second problem! Immediately after generation, the oxide layer has micropores that still need to be closed.
A final compaction or sealing closes these pores to create a layer consisting largely of aluminum hydroxide (the workpiece can also be boiled briefly for this purpose). This anodically produced oxide layer together with the sealing thus has a much better resistance for our purpose. However, the elements already mentioned and built into the aluminum also sometimes lead to flaws in the oxide layer. The consequence is that the dissolving elements then also strongly increase the dissolution, which of course noticeably affects the coating quality. Here we have already found the second predetermined breaking point for the corrosion that will later spread. And some companies add a kind of coating with a very thin varnish for a better look. Meaningless for cooling, but unfortunately true and seen quite often. And sometimes even with missing parts.
And what is a part made of nickel-plated copper doing in such a circuit? It also accumulates quite a bit!
The lid also still shows the green-gray slime, but it is not found in the solid, white-yellowish residue of the GPU block:
Summary and conclusion
The conclusion can be made short, because in general you can make all these things from aluminum, but in return you must also pay attention to clean manufacturing. Mixing aluminum with copper and brass in a circuit, on the other hand, is counterproductive, because the holes in the oxide layer will now ALWAYS exist. If aluminum, then please everything made of aluminum or nothing at all! No expensive anti-corrosives will help if silica reactions and mucus occur later. So here the manufacturer is first in responsibility. Period.
Let’s now take a quick look at the Gigabyte GeForce RTX 3080 GAMING OC WATERFORCE WB. The fact that the card is obviously also no longer available in the meantime can only be welcomed. What doesn’t work at all from the customer’s point of view, on the other hand, is the obvious discrepancy between PR and marketing statements that the product is copper. Because exactly the opposite is in fact the case. Here, the customer falls into a deep, technological hole without knowledge and being completely unprepared. And if the aluminum cooler was also processed so carelessly, as was the case with all seven cards, then good night. This just HAS to break.
This card from Gigabyte is representative for a very cheap production under enormous cost pressure, whereas the high price of the card doesn’t really justify that. The cooler could have been made much better and more durable with a few more USD. The reproach therefore goes first of all to the controlling department for the cost down, the contract manufacturer for the very sparse implementation without real quality management, and the PR department, which advertises things that should not be communicated in this way. After all, the websites didn’t just make up this misleading information about copper out of thin air.
My thanks go to the community for providing the test objects or data and photos, as well as a friendly laboratory for the chemical expertise and analysis.
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