How to prevent accelerated corrosion in things you care about.
Metals corrode faster when in **electrical contact** with a **more noble metal** in the **presence of an electrolyte**.
Under these three conditions **galvanic corrosion** occurs. The less noble metal dissolve into the electrolyte. The more noble metal’s corrosion is inhibited. Former becomes an anode, latter a cathode.
Alloys and other electrically conductive materials like carbon fiber (graphite) are also subject to galvanic corrosion.
**Measures to prevent** galvanic corrosion are analogous to the causes: use **similar metals**, **electrical isolation** and **moisture sealing**.
Metals are “similar” when their electropotential difference is small (<250mV). This difference can be looked up in **galvanic series** charts.
![[Galvanic Corrosion, in 218 Words-20241102201455672.jpg]]
For example, **cadmium-plated fasteners in aluminum alloys** have little galvanic corrosion potential. Similarly, **stainless steel fasteners in carbon fibers** (graphite) exhibit little potential.
Having **more mass in the less noble metal mitigates the effects** of galvanic corrosion. For example, stainless steel screws impact big aluminum alloy structures far less than stainless steel structures would impact aluminum alloy fasteners.
**Electrical isolation** is an effective strategy as well. With carbon fiber parts it is common practice to add a layer of fiberglass in areas of contact with other metals. Alternatively a layer of primer is often used on nutplates in carbon fiber parts.
Parts that can be effectively **sealed from moisture** are also safe from galvanic corrosion.