Galvanic Corrosion
Contents
Basics
- Also referred to as dissimilar metal corrosion
- A Type of Corrosion that occurs between two dissimilar metals in presence of an Electrolyte
- Can Be Prevented By:
- Separation (Coatings/Material Choices, or if necessary a process that separates potential electrolytes from the materials, such as in Copper Clad Aluminum Wire )
- Sacrificial Anodes
- Impressed Current Cathodic Protection
Marine
- Silicon-bronze screws are for marine environments [1]
Protection
- Rubber washer
- Epoxy around threads [2]
- Permatex #3, Tefgel, Duralac, Lanocote are good coats for preventing galvanic corrosion [3]
Fasteners for Aluminum
- This article says that stainless is best for screwing in aluminum, but must minimize corrosion such as rubber washer between screw head and aluminum sheet. It does not talk about contact between threads of screw and the aluminum - it appears the head is more important than the threads. [7]
- Stainless and galvanized are ok with aluminum, as long as not salty environment [8]
- This forum says epoxy coat screws for aluminum [9]
Deck Screws
- Are deck screws compatible with aluminum? Some deck screws are polymer coated so they should work with aluminum if polymer doesn't srip
- Deck screws are G185 or polymer coat [10]
- Polymer coat on deck screws is epoxy [11] or ceramic [12]
- Triple Coated Deck Screws - two coats over galvanized screw [13] but not for marine.
Pole Barn Screws
- 1" menards - [14]
- They are galvanized - [15]
- Stitch screws - for bonding short lengths of metal [16]
Drill Point Screws
Aluminum and Galvanized Steel
- Not compatible. Use rubber washer between.
Shopping
- Galvanized pole barn screws for aluminum [19]
Wiring
- Galvanic Corrosion with improperly installed Aluminum Wiring was (and to a certain extent still is) a MAJOR issue in Home Wiring
- If the proper fittings etc are issued there is no issue, but a direct copper-aluminum splice, or using switches/receptacles not Listed for one and/or the other etc can cause MAJOR issues, and as always with electrical a FIRE RISK
