Hoosier
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Theoretically, yes. But, it is pretty much cosmetic...
Q about aluminum backplates
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Theoretically, yes. But, it is pretty much cosmetic...
MSilvia
Contributor
Nice troll, and kudos on your smooth perpetuation of misinformation. :whack:
The aluminum will not turn to powderand blowaway. It will get a white film which I pretty much ignore and it seems self limiting. I would not worry over it myself. N
cool_hardware52
Contributor
Ah aluminum plates and anodizing.
Anodizing is the controlled application of Aluminum Oxide (AO) AO is a brittle, hard ceramic coating. Aluminum will naturally develop an oxide coating almost instantly after being cut or machined.
If an aluminum part is colored, i.e dyed, it is almost certainly Type II, although Type III (hardcoat) is sometimes dyed black.
Hardcoat anodizing offers the advantage of a thicker coating, ~.002" vs .001" for Type II.
In terms of performance on a Scuba backplate it is important to remember that a thin hard brittle coating is no stronger than the underlying aluminum. 5000 series aluminum is most often used for marine applications, and it performs quite well even when not anodized. 5000 series aluminum is not heat treatable, and will remain fairly soft.
What happens when you apply a hard, thin, brittle coating over a soft substrate? It fails wherever localized point loads are applied, such as spring lock washers and thumbscrews. The underlying material distorts and the thin brittle coating cracks or chips off.
Hardcoat anodizing is an excellent treatment for hard aluminum parts (2000 series, or 7000 series) that will be subjected to abrasive wear, such as two parts sliding against each other. Fork tubes on a motorcycle for example, or internal pump parts. Aircraft hydraulic pumps are a classic application.
Hardcoat anodizing a soft 5000 series part is in my opinion a waste of time, pure marketing.
Remember, scuba tanks are 6061 aluminum, which is less corrosion resistant than 5000 series, and with minimal care these aluminum tanks perform fine for long periods without any coating.
Tobin
Anodizing is the controlled application of Aluminum Oxide (AO) AO is a brittle, hard ceramic coating. Aluminum will naturally develop an oxide coating almost instantly after being cut or machined.
If an aluminum part is colored, i.e dyed, it is almost certainly Type II, although Type III (hardcoat) is sometimes dyed black.
Hardcoat anodizing offers the advantage of a thicker coating, ~.002" vs .001" for Type II.
In terms of performance on a Scuba backplate it is important to remember that a thin hard brittle coating is no stronger than the underlying aluminum. 5000 series aluminum is most often used for marine applications, and it performs quite well even when not anodized. 5000 series aluminum is not heat treatable, and will remain fairly soft.
What happens when you apply a hard, thin, brittle coating over a soft substrate? It fails wherever localized point loads are applied, such as spring lock washers and thumbscrews. The underlying material distorts and the thin brittle coating cracks or chips off.
Hardcoat anodizing is an excellent treatment for hard aluminum parts (2000 series, or 7000 series) that will be subjected to abrasive wear, such as two parts sliding against each other. Fork tubes on a motorcycle for example, or internal pump parts. Aircraft hydraulic pumps are a classic application.
Hardcoat anodizing a soft 5000 series part is in my opinion a waste of time, pure marketing.
Remember, scuba tanks are 6061 aluminum, which is less corrosion resistant than 5000 series, and with minimal care these aluminum tanks perform fine for long periods without any coating.
Tobin
I made my ali plate about 3 years and 300 dives ago....It was never anodixzed and while it has white spots it is as sound as the day I made it. It cost me about $15 or less dollars to make.
halocline
Contributor
If you're going to use your AL plate as a griddle for those post dive BBQs you might want to go with anodized to help prevent alzheimer's. Otherwise I can't imagine it's worth paying extra for.
giles45shop
Contributor
Just to clarify a little more:
Anodizing is essentially enhancing the growth of a thicker than normal oxide layer on the surface of the aluminum through a controlled corrosion process. All aluminum has a native oxide layer, this is just a thicker version.
It is not like plating where another material is deposited on top of the exiting material. With anodizing, some of the base aluminum is converted through oxidation (corrosion) into aluminum oxide. This is done with the use of acids and electrical currents.
It is also not strictly a ceramic as the microstructure/crystal structure of anodize is different than that of aluminum oxide ceramics, although it is a relatively hard substance.
John
Who Plays at Being a Materials Engineer for a Large Aersopace Company when not diving
Anodizing is essentially enhancing the growth of a thicker than normal oxide layer on the surface of the aluminum through a controlled corrosion process. All aluminum has a native oxide layer, this is just a thicker version.
It is not like plating where another material is deposited on top of the exiting material. With anodizing, some of the base aluminum is converted through oxidation (corrosion) into aluminum oxide. This is done with the use of acids and electrical currents.
It is also not strictly a ceramic as the microstructure/crystal structure of anodize is different than that of aluminum oxide ceramics, although it is a relatively hard substance.
John
Who Plays at Being a Materials Engineer for a Large Aersopace Company when not diving
Gilldiver
Contributor
First off, we have been throwing out things like Type II and Type III anodize. These types go back to Military specification MIL-A-8625. The latest revision is from 1993 with an amendment in 2003.
The Types are
Type I Chromic Acid Anodize
Type IB Chromic Acid Low voltage
Type IC Non-Chromic Acid Anodize (Boric Sulfuric Anodize developed by Boeing in the early 90s to get away from the Environmental problems involved with chromic acid)
Type II Sulfuric Acid Anodize
Type IIB Thin Film Sulfuric Acid Anodize (Another environmental alternative to Chromic Anodize)
Type III Hard Anodize
For the laymen out there, these three pages will give you more info then you really want to know.
JobShop.com Technical Article: Anodizing: Type II (Sulfuric) and Type III (Hardcoat) Hi-Tec Plating, Inc. Statesville NC North Carolina
JobShop.com Technical Article: Aluminum Anodizing and Hard Coat Anodizing East West DyeCom, Inc. Roanoke VA Virginia
JobShop.com Technical Article: The Many Faces of Aluminum Light Metals Coloring Company Inc. Southington Connecticut CT
I was wrong in my first post, you can dye Hard Anodize per the MIL-A. The aircraft specs I usually work with do not allow it.
Pete, who actually has to design anodize processing lines for Aerospace when not diving, which seems to be the rule this year - CT, Turkey, Poland, China.... Only good point is the frequent flyer miles are starting to stack up.
The Types are
Type I Chromic Acid Anodize
Type IB Chromic Acid Low voltage
Type IC Non-Chromic Acid Anodize (Boric Sulfuric Anodize developed by Boeing in the early 90s to get away from the Environmental problems involved with chromic acid)
Type II Sulfuric Acid Anodize
Type IIB Thin Film Sulfuric Acid Anodize (Another environmental alternative to Chromic Anodize)
Type III Hard Anodize
For the laymen out there, these three pages will give you more info then you really want to know.
JobShop.com Technical Article: Anodizing: Type II (Sulfuric) and Type III (Hardcoat) Hi-Tec Plating, Inc. Statesville NC North Carolina
JobShop.com Technical Article: Aluminum Anodizing and Hard Coat Anodizing East West DyeCom, Inc. Roanoke VA Virginia
JobShop.com Technical Article: The Many Faces of Aluminum Light Metals Coloring Company Inc. Southington Connecticut CT
I was wrong in my first post, you can dye Hard Anodize per the MIL-A. The aircraft specs I usually work with do not allow it.
Pete, who actually has to design anodize processing lines for Aerospace when not diving, which seems to be the rule this year - CT, Turkey, Poland, China.... Only good point is the frequent flyer miles are starting to stack up.
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