Dissimilar Metal Compatibility Matrix: A
Dissimilar metal compatibility matrix — required protective treatment level (1–9, where 1=maximum protection required and 9=minimal or no protection needed) for each pair of metal groups (A–T, anodic to noble) per MIL-STD-889C Table I. Covers three service environments: seawater, marine atmosphere, and industrial atmosphere. Also flags same-metal diagonal entries. Used to determine dissimilar metal joint protection requirements in aerospace, marine, and industrial structures. Complement table: Surface Treatment Specs (dissimilar_metal_protection_* PKs) lists the specific protective treatments corresponding to each protection level.
| metal a code | metal b code | borderline marine atm | borderline seawater | metal a name | metal b name | notes | protection level industrial atm | protection level marine atm | protection level seawater | same metal compatible |
|---|---|---|---|---|---|---|---|---|---|---|
| A | B | false | false | Magnesium | Zinc coating | Mg is active anode; maximum protection required in all environments | 1 | 1 | 1 | false |
| A | C | false | false | Magnesium | Cadmium/Beryllium | Mg is active anode; maximum protection required in all environments | 1 | 1 | 1 | false |
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