Aluminum coating for good surface wetting with (bidistilled) water

What kind of environment would this coating be subjected to for the ten years?

A. I think the issue here is not to reduce the surface energy of water but to increase the surface tension of the aluminum. I would think a thorough anodizing should do the trick, as you should expect a critical surface tension greater than water, thus making the interaction of the surface & the water hydrophilic. Roughing the surface by mechanical means may help as well.

At the other end, a coating of titanium dioxide will increase the critical surface tension to 91, a ferric oxide coating to 107 or a tin oxide coating to 111. Wettability is primarily a matter of making sure the critical surface tension of the substrate is greater than the critical surface tension of the liquid. Dry aluminum has a critical surface tension of about 45, meaning it is not normally wetted by water.

A. Dear Delahaye:

We have a similar question as you showed. My project is to get the surface tension of aluminum/oil system at the room temperature. According to the Young Equation G(s,v)=G(s,l)+G(l,v)cos(angle),which G express the surface tension. s express the solid,v express the vapor, l express the liquid. the G(l,v),which is the surface tension of oil(liquid and Air) G(s,l) expressed the surface tension of aluminum(solid) and oil(liquid). The G(s,v), which express the surface tension of aluminum(solid) and air. From the equation, the G(l,v) can be obtained from the pendant drop method, Angle can be obtained from sessile method.In order to obtained the G(s,l),the G(s,v)have to first to be known.

So the question I have is what is the G(s,v) at room temperature. If I get it, I can further calculate the surface tension of aluminum/oil.

A. Dear Ms.Ann Delahaye,

The Dehumidifying(or Wetting) method of aluminium coating that you have been seeking can be solved by the way of One layer or Two layer system of hydrophilic coating for aluminium fin stock because of life time (duration) to be short. 7 degree of contact angle is accepted. There are two methods, the one is pre-coating method (coil coating) and the other is post coating method(immerse coating).

A. You might look at lithographic printing where an aluminum substrate is made hydrophilic, and an overcoat of copper, or a polymer is made hydrophobic. I was using the search engine BING (Canadian), and searched "Lithography - is aluminum hydrophobic?". One item that showed up is "Hydrophylic Properties Overview - aluMATTER / Aluminum ...". The incomplete web address starts aluminum.matter.org.UK/Content/html/... Essentially, in its discussion it states that the aluminum area of lithographic printing plates are made hydrophilic by the technique of AC-electrograining or AC-graining. Nitric acid or hydrochloric acid in a bath attacks the aluminum plates as an alternating current goes through the bath to make fairly uniform size, depth and spacing pits that help to make the aluminum area of the printing plate more hydrophilic. If this is of interest, then try to find a printing plate manufacturer to see how they do it.

Hi Miss Ann.

I am in HMX heat mass exchanger (cross-flow and counter-flow).
I have tried a roughening method on aluminum surface using orbital sander and sanding paper 40 Grit.
The result is not bad especially when I use a surfactant agent to promote the adhesion of water on treated aluminum surface and reduce the surface tension.
Once the surface is saturated with water film, the evaporation effect becomes superb but of course not as good as hydrophobic-phillic membrane.

Ciao,