Aluminum Anodes

[LONG_KEELER]

I notice that there is a choice of either zinc or aluminium on some outboards and outdrives for salt water. A search suggests that aluminium is ok but the surface needs to be kept clean. Their is quite a price difference favoring aluminium.

Any thoughts or experience ?

TIA

 

[harvey38]

Got an aluminum one one on my little 2.5 Suzuki that seems to be very gently fizzing away in salt water, not cleaned off the surface.

 

[vyv_cox]

Aluminium is the future for anodes, zinc is becoming increasingly expensive. I am not aware of any special requirement for keeping them clean. I had an article on them in YM within the past two years

 

[yotter]

Just thinking aloud, how will an aluminium anode protect aluminium underwater structures such as saildrive legs, or is down to the composition of the different alloys?

 

[VicS]

Just thinking aloud, how will an aluminium anode protect aluminium underwater structures such as saildrive legs, or is down to the composition of the different alloys?

Aluminium anodes are a special alloy containg some zinc and crucially a small %age of indium.
It is slightly more anodic than zinc so in theory a little bit more effective

 

[yotter]

Aluminium anodes are a special alloy containg some zinc and crucially a small %age of indium.
It is slightly more anodic than zinc so in theory a little bit more effective

Vic,
Many thanks for that, you beat Viv to it

 

[Graham_Wright]

Aluminium anodes are a special alloy containg some zinc and crucially a small %age of indium.
It is slightly more anodic than zinc so in theory a little bit more effective

I have a stack of T6082 from a frustrated order. Is that any good?

 

[vyv_cox]

I have a stack of T6082 from a frustrated order. Is that any good?

Unfortunately not. . One aluminium anode composition that I have is a fairly complex mixture of closely controlled elements.
Zinc (Zn) 3.50 - 5.00
Titanium (Ti) 0.01 - 0.05
Silicon (Si) 0.05 - 0.20
Bismuth (Bi) 0.05 - 0.15
Indium (In) 0.02 - 0.05
Copper (Cu) 0.01 max
Iron (Fe) 0.15 max
Others each 0.10 max
Aluminium Balance

My abbreviated galvanic series chart shows the aluminium anode composition to bes more anodic than aluminium alloys, which would include your T6082, aluminium with mostly magnesium, manganese and silicon, with a few others.