Tech Tour Seminar Series
Scott de Recat – Derema Group
Corrosion 101
What is Galvanic Corrosion?
When a metal is immersed in an electrolyte (salt, brackish, or fresh water) small
electrical cells begin to form on the metal’s surface as a result of a chemical
reaction.
In time, the metal becomes polarized and material is lost from the anodic pole
of these cells. This causes the damage we know as galvanic corrosion.
An even stronger effect is produced when two different metals are electrically
connected in the same electrolyte.
Corrosion 101
The Noble Scale
M III - Mg (-1450 mV)
M II - Al
M I - Zn
Galvanized Steel
Aluminum
Mild Steel
Iron
Tin
Bronze
Brass
Nickel
Copper
Stainless Steel
Silver
Gold (+1420mV)
ANODIC METALS
(MOST ACTIVE, LEAST NOBLE)
THE MORE SPACE YOU
HAVE BETWEEN METALS,
THE MORE ELECTRICAL
CURRENT IS DERIVED
CATHODIC
(LEAST ACTIVE, MORE NOBLE)
Corrosion 101
Martyr Anode Alloy Breakdown
Composition
MI
Zinc Alloy
MIL-A-18001K
MII
Aluminum Alloy
MIL-A-24779 (SH)
MIII
Magnesium Alloy
AZ-91-D
Cadmium
Copper
Iron
Indium
Lead
Mercury
Silicon
Nickel
Manganese
Magnesium
Aluminum
Zi nc**
0.025% - 0.07%
0.005% Max.
0.005% Max.
-0.006% Max.
-----0.1% - 0.5%
Rem ainder
-0.004% Max.
0.090% Max.
0.014% - 0.020%
-0.001 M ax.
0.08% - 0.20%
---Rem ainder
4.0% - 6.5%
-0.030% Max.
0.005% Max.
---0.10% Max.
0.002%
0.15% - 0.50%
Rem ainder
8.3% - 9.7%
0.35% - 1.0%
* * ”M I Zinc a nod es ha ve a zinc p urity of 99.995%
Specifications
MI
Zinc
Alloy
MII
MIII
Aluminum Magnesium
Alloy
Alloy
CAPACITY, ampere-hours per pound
355
1225
500
EFFICIE NCY (t est)
95%
94%
50%
CONSUMP TION, pound per ampere-year
24.5 lbs
7.6 lbs
17.5 lbs
POTE NTIAL (reference Cu/ CuSO4)
-1050mV
-1100mV
-1450mV
Corrosion 101
3 Different Anodes for 3 Different Water
Environments
There used to be only 1 anode type – Zinc. But over many years OEM’s, boat
builders and the general boating public realized that there were too many
variables when it comes to key boating areas and proper protection and
thus the evolution of 3 different anode alloys.
Corrosion 101
3 Different Anodes for 3 Different Water
Environments
Zn





Al
Mg
Salt Water Only!
Does not work in fresh & brackish water
Very Heavy and Shiny
Looks “sandblasted” as it corrodes.
Readily Available.





Salt & Brackish Water
Does not work effectively in pure fresh water
Very Light, Dull Silver in Color
“Pits” as it corrodes.
Available in Commercial & Pleasurecraft lines
Used by most OEM’s

Fresh Water Only!

Cannot be used in salt or brackish water

Extremely light. Dark Grey in Color

Available in Pleasurecraft only

Corrosion 101
Recent News - Anodes & The Environment
Corrosion 101
Recent News - Anodes & The Environment
WA DOE Boatyard General Permit
Guidelines – Page 14
Corrosion 101
So now what are your options?
Aluminum Anodes - Benefits
• Contain No Cadmium. Primary elements are Aluminum and Indium
which are non-toxic
• Better efficiency and performance vs. Zinc
• Improved corrosion protection
• Reducing the quantity of anodes required
• Longer performance life
• Lighter in weight then Zinc anodes
• Less costly than Zinc anodes
Martyr Brands them as “Cadmium-Free” MII Anodes
• Other companies offering Aluminum Anodes include
•
Performance Metals, Sea Shield and Reliance
Corrosion 101
Who’s using Aluminum Anodes
• US Navy
• Canadian Navy
• US and Canadian Ferry Fleet
• Oil and Gas Industry – Offshore drilling platforms
• Leading dock manufactures world wide
• All US/Japanese engine manufacturers
•
Mercury
•
Volvo
•
BRP
•
Honda
•
Yamaha
Corrosion 101
What has been written about Aluminum vs. Zinc?
Seaworthy/ Boat US Standards:
“Below the waterline, when you have a stainless steel shaft and a
bronze prop, which can’t be isolated, you’ll need an anode —
either zinc, magnesium or aluminum — that will be sacrificed to
save the fitting. Zinc can be used in saltwater; magnesium can be
used in freshwater (never in salt or brackish water); but the most
widely affective anodes these days are being made of
aluminum, which can last up to 50% longer, and remain active
in brackish and saltwater. How, you may ask, does an aluminum
anode protect an aluminum outdrive? The answer is that an anode
is made with an aluminum alloy that is significantly different (more
anodic) than the alloy used on an outdrive.”
Corrosion 101
What has been written about Aluminum vs. Zinc?
West Advisor: Getting rid of Cadmium and Zinc
“Zinc and cadmium are elements used in traditional salt-water
anodes that are suspected of causing environmental damage.
CMP Global has re-formulated their product, removing these alloys
for safer more “green” anodes. A rare bit of good news for the
boater: these new formulations actually work better! They’re lighter
and last longer, so they’re a plus for your boat and for the
underwater life in your marina”.
Corrosion 101
What has been written about Aluminum vs. Zinc?
Marine Log – April 2012 Issue
Crowley Marine – VP of Engineering – Bill Metcalf
Crowley’s vice president, Engineering, and
a 30-year Crowley veteran, Bill Metcalf
says the company has used aluminum
anodes “since before I joined the
company”. The reason? “it’s based on
utilization. The aluminum anodes will last
longer in the water, they have a better
performance life, say Metcalf”.
Corrosion 101
What has been written about Aluminum vs. Zinc?
Artist, Sport Fishing Professional, Environmentalist, Editor
Guy Harvey – Summer 2012 Guy Harvey Magazine
Corrosion 101
FAQ’s about Aluminum vs. Zinc?
• Can I use aluminum anodes on my aluminum boat?
• Why doesn't Martyr produce aluminum pencil anodes?
• Can I mix aluminum anodes with zinc anodes?
Corrosion 101
What to look for in Anode Protection
Quality
•
MIL Spec Products are critical – Reliable Performance.
•
Products produced in an ISO 9001 Certified Facility
•
In-house lab testing ensures adherence to the Mil Spec
alloy material (zinc, aluminum & magnesium)
•
Approved vendor to many OEM, Government & Military
organizations around the world
Product Availability - Bulk & Packaged Anodes
•
Product availability in all 3 alloys (only manufacturer to do so)
•
Products available for most popular marine engines/ systems
•
Key boatyard products including commercial plates
•
2 choices of shaft/ rudder/ collar hardware – hex & slotted in stainless
•
Over 50 new products launched every year (over 400+ parts now!)
Corrosion 101
What does Martyr have to offer?
Customer Service/ Support
•
Factory & Rep support in the field
•
Factory personnel trained in Corrosion Control through NACE
•
Worldwide distribution network
•
•
Fisheries Supply
•
Diversified Marine Products
•
Redden Marine
•
Port Supply
Large range of support material available
Corrosion 101
Did we mention support…
Catalogs
Posters/ Flyers
POP Items
Website
www.martyranodes.com
Corrosion 101
Did we mention support…
Custom FAB’s
Sell Sheet
Available
Just ask!
Corrosion 101