Anode Material

[FreeBeeTony]

Which is preferred in salt water?
Zinc or Aluminum?

 

[alldodge]

Depends if its a IB or I/O see chart

 

[FreeBeeTony]

Kinda surprised/comfused......can't quite understand why an aluminum anode would be used on an aluminum outdrive...

 

[Scott Danforth]

because it lasts a bit longer than zinc. I still prefer a new zinc every year.

 

[alldodge]

Kinda surprised/comfused......can't quite understand why an aluminum anode would be used on an aluminum outdrive...

Aluminum outdrive is painted (has insulation), the anode is not

 

[QBhoy]

Also that the aluminium anode isn’t just quite all aluminium, or at least the same make up as the outdrive. Slightly different make up and maybe a bit miss leading in calling it so. The anode and it’s make up is made to be of a more sacrificial make up than the drive. If you know what I mean. I remember looking into this I’m great detail previously, one of the reasons was just the same question as you.

 

[dingbat]

Kinda surprised/comfused......can't quite understand why an aluminum anode would be used on an aluminum outdrive...

The short answer is most aluminum is not aluminum.

Most aluminums are alloyed with a number of different elements to give it specific electrical and mechanical properties.

A number of the elements commonality alloyed are more “active” than the aluminum. Therefore, you can change the nobility of the material by changing the compostion.

As long as the anode has a higher nobility than the out drive, your good

https://performancemetals.com/pages/...luminum-anodes

 

[achris]

...As long as the anode has a higher nobility than the out drive, your good...[/URL]

Errr, no. You want the LEAST noble metal to be the anode.

Galvanic series (most noble at top)


The following is the galvanic series for stagnant (that is, low oxygen content) seawater. The order may change in different environments.[SUP][1][/SUP]

• Graphite
• Palladium
• Platinum
• Gold
• Silver
• Titanium
• Stainless steel 316 (passive)
• Stainless Steel 304 (passive)
• Silicon bronze
• Stainless Steel 316 (active)
• Monel 400
• Phosphor bronze
• Admiralty brass
• Cupronickel
• Molybdenum
• Red brass
• Brass plating
• Yellow brass
• Naval brass 464
• Uranium 8% Mo
• Niobium 1% Zr
• Tungsten
• Tin
• Lead
• Stainless Steel 304 (active)
• Tantalum
• Chromium plating
• Nickel (passive)
• Copper
• Nickel (active)
• Cast iron
• Steel
• Indium
• Aluminum
• Uranium (pure)
• Cadmium
• Beryllium
• Zinc plating (see galvanization)
• Magnesium

 

[QBhoy]

You want the anode less noble for sure. Check the galvanic scale. All the best.

 

[dingbat]

Errr, no. You want the LEAST noble metal to be the anode.

You are correct.

I’m accustomed to checking voltages..higher is better but nobility is inverse. Higher = less