Sergei,
The entire interior of my CCD is aluminum, including the wall behind the kitchen that forms the backsplash. I don't believe that it has a special coating on it, and it is holding up very well.
Metals prices are going thru the roof, as is just about everything else. If you feel the need to coat the aluminum you are using for your backsplash, any high quality automotive clearcoat should work well, as it resists UV and gasoline spills on cars and trucks, and will probably do the same for anything found in the kitchen.