GLENAIR
For example, zinc and/or cadmium coatings are electronegative (or anodic) to steel (2) . The mechanics of this corrosion protection system are shown in Figure 1 . The reaction in this process involves zinc
giving up electrons to the steel substrate and zinc leaving the matrix as an ion. The steel substrate then passes on the electrons gained from zinc to the hydrogen and therefore remains protected.
ANODIC INDEX (0.01 V)
GROUP NUMBER METALLURGICAL CATEGORY
EMF (V) +0.30 +0.15 +0.05
COMPATIBLE COUPLES 1
○
Inorganic carbon (carbon fibers, graphite, graphene, etc.) 2 Gold, solid or plated; gold-platinum alloys; wrought platinum Rhodium plated on silver-plated copper Silver, solid or plated; high silver alloys Nickel, solid or plated; Monel® metal; high nickel-copper alloys; Titanium and Titanium alloys, Inconel® alloys, Hastelloy® C276 Copper, solid or plated; low brasses or bronzes; silver solder; high copper- nickel alloys; nickel-chromium alloys; austenitic corrosion-resistant steels
0
0
●○
1 2 3
15 25 30
●●○ ●●●○
0
●○●●○
4
-0.15
45
●○●●●○
5
-0.20
50
●○○●●●○ ○●○○●●●○ ○●○○●●●●○
6 7
Commercial yellow brasses and bronzes -0.25
55 60
High brasses and bronzes; naval brass; Muntz metal 18 percent chromium type corrosion- resistant steels Chromium plated; tin plated; 12 percent chromium-type corrosion-resistant steels Tin plate; terneplate; tin-lead solder Lead, solid or plated; high lead alloys Aluminum; wrought alloys of the 2000 series Iron, wrought, gray, or malleable; plain carbon and low-alloy steels; Armco® iron Aluminum, wrought alloys other than 2000 series aluminum; cast alloys of the silicon type Aluminum, cast alloys other than silicon type; cadmium, plated and chromated Hot-dip zinc plate; galvanized steel Zinc, wrought; zinc-base die-casting alloys; zinc, plated Magnesium and magnesium-base alloys, cast or wrought
-0.30
8
-0.35
65
9
-0.45
75
●○○○○●●●●○ ●○○○○○●●●●○ ●○○○○○○●●●●○ ●○○○○○○○○●●●○ ●○○○○○○○○●●●●○
10 11 12
-0.50 -0.55 -0.60
80 85 90
13
-0.70
100
○●○○○○○○○○●●●●○
14
-0.75
105
15
-0.80
110
○●○○○○○○○○○●●●●○ ○●○○○○○○○○○○○○○●○ ○●○○○○○○○○○○○○○○● ○○●○○○○○○○○○○○○○○●
16 17
-1.05 -1.10
135 140
18
-1.60
190
Notes: 1. ○ indicates the most cathodic member of the series, ● indicates an anodic member. Arrows indicate the anodic direction. All corrosion-resistant steel (CRES) in this table is passivated . 2. All conductive carbon forms, including structures and coatings comprised of carbon composites, carbon fibers, graphite, pitch carbons, carbon black, vitreous carbons, carbon/carbon, graphene, phenolic-impregnated carbon ablative (PICA) materials, etc. Table 1: Metallurgical Category vs. Electro-Motive Force with Respect to SCE in Seawater(1) from NASA-STD-6012A
QwikConnect • April 2023
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