Chemistry question on aluminum

Most aluminum products are clear coated or anodized to prevent oxidation. i.e. Rowland as an example. If you look at a car aluminum wheel, the are all anodized.

Aluminum reacts with oxygen to form aluminum oxide. This oxide will completely cover the surface between the raw aluminum and the atmosphere and prevent any additional reaction with oxygen. The layer formed is about 3 to 4 nanometers in thickness. The process of anodizing aluminum actually increases the thickness of this layer and makes it harder.

Do not worry about your modern aluminum audio products for use in your lifetime.

Far more manufacturers using aluminium chasis. Most of heatsinks are aluminium. The lifespan of aluminium chassis is far larger than human lifespan so nothing and nothing to scratch your head about in any case. Raw aluminium can be toxic if digested so it's not recommended to cook a food on untreated aluminium. Other than that there's no toxines getting airborn off the aluminiumn surface.

I hate to make you even more paranoid.Aluminum is also thought to cause alzheimer's...

Unless you live next to a saltwater spray you should be fine with anodized aluminuim casework etc. Untreated Aluminium will react as has been said but most of what you end up with is treated in some way or other.

I live and work near the Pacific Ocean. Aluminum even NEAR the ocean will turn to a powdery dust if left untreated. I remember as a child we would have to replaice our aluminum patio furniture every year as it would weaken and become unsafe. I worked for the Telephone company and in coastal zones we used copper or stainless steel in lieu of aluminum to stop the disinitegration of our outside plant infrastructure.

Are there any Phd's in chemistry out there who can answer this without equivocation? I doubt any respondents thus far have an education degree of any type in chemistry.

What's the alternative, steel?

Salt water air will penatrate treated and untreated aluminium almost as quick and turn it to dust quick.

For homes next to the beach I'd recommend keeping AC on all the time to keep the moisture at its minimum.

I would be concerned if I lived very close to a beach with salt spray present in the air. Absent salt spray, Drrsutlif's comments are accurate. As far as aluminium and alzheimer's disease, that arose from a finding that amyloid plaque contains elevated levels of aluminum. Current thinking is that this is a coincidental not a causual relationship.

Aluminum melts at 1220˚F, so depending on how hot it is where you live there could be concerns. Just something to be equally paranoid about.

Unless your listening room is situated on the face of the planet Mercury, I don't think I'd worry too much about high ambient temps...

-RW-

I never got my PhD, but I did have a beach house at one point. A quick glimpse at the coated aluminum frames of my deck furniture will confirm that salt air is not good for aluminum.

Marty

First response is the one that makes practical sense. Would any of you have sympathy for or buy anything from a neglectful lazy pig who after spending good money on gear lets it rot, never paying attention to it's appearance? My goodness! Wipe it off with a damp cloth once in a while, dust it off, don't use it as a coffee table and spill beer on it. Take the same care as anyone anywhere and it'll still look great 20 years later.

Caveat: don't forget to take the lid off and blow it out with compressed air too.

As mentioned Drrsutliff, the surface of aluminum oxidizes to create a coating of aluminum oxide. This surface adheres strongly to the aluminum and protects the unoxidized aluminum beneath it. Steel, as we know also oxidizes, however this creates rust which progressively falls away from the metal beneath thus allowing the oxidation to spread.

If aluminum comes into contact with salts or caustics it will cause the oxidizes to go on and spread like rust on steel.

Anodization of aluminum thickens the hard oxide layer and increases the protection against corrosion. This is generally sufficient for most applications.

I live in Quebec. We are not close to the sea but during winter the cities spread copious amounts of salt on our roads. IME The salt seems to have little impact on aluminum wheels. Mind you, I remove my al wheels and replace them with old rusty steel rims. Many other car parts are also made of al such as engine blocks and heat exchangers. I have never heard of them failing due to corrosion.

All this to say, that for audio applications I would not be the least bit worried with use of aluminum. The question is are there other materials, for audio applications, that will perform better such as carbon fibre or Kevlar?

Formerly, I worked for a leading aluminum producer.

As for toxicity, aluminum is not toxic and eating from it is in no way dangerous. Good luck not eating food that is or was in contact with al. Think al foil.

As for the link with Alzheimer's, my understanding is that al is found in the brains of patients but that arrives their "naturally" and is not a result of exposure.

There is little chance that any aluminium used in commercial audio products is in its 'raw' state.....ie...unprotected.
At the very least, a chromate coating is the cheapest but anodising is generally the most economically available product and is available in a range of colors and thicknesses (the thicker the coating...say 25 microns...gives added protection).
Powder coating of aluminium is generally cheaper than anodizing these days and is available in hundreds of colours compared to the limited range with adodising.
Powder coating provides greater protection against the corrosion of salt being a paint sealant rather than a chemical deposit as in anodising.
Anodised aluminium WILL be eaten away by salt near a marine environment and even with powder coating......any weakness in joints, edges, drilled fixing holes etc will be attacked thus making any form of aluminium in a marine environment very risky.
Two-pack polyurethane is another protective coating which can be used over aluminium but stainless steel, zinc, copper and even galvanized steel are preferable for coastal environments.
Heat and humidity in themselves will not affect any commercially protected aluminium products.

I've seen aluminum body work on cars corrode away exactly like rusty steel. The probable reason you don't see it to that extent on wheels is because they are made with alloys of aluminum, not pure. Same goes for audio component cases, I would think for the sake of durability. Although certain types of racing wheels are typically pure aluminum/magnesium.

Thank you everyone for corroding away my paranoia. ;p