This annex gives information on the salt spray corrosion protection performance of zinc and cadmium coatings with chromate treatment (see Tables B.1 and B.2 ) and of nickel and nickel/chromium coatings (see Table B.3) under the conditions of the salt spray test according to ISO 9227.
Neutral salt spray corrosion protection performance of zinc and cadmium| Designation code for coatings a (System B b) | Nominal coating thickness | Chromate treatment designation c | First appearance of white corrosion product | First appearance of red rust | |
|---|---|---|---|---|---|
| Cadmium | Zinc | ||||
| μm | h | h | h | ||
| Fe/Zn or Fe/Cd 3c1A | 3d | A | 2 | 24 | 12 |
| Fe/Zn or Fe/Cd 3c1B | B | 6 | 24 | 12 | |
| Fe/Zn or Fe/Cd 3c2C | C | 24 | 36 | 24 | |
| Fe/Zn or Fe/Cd 3c2D | D | 24 | 36 | 24 | |
| Fe/Zn or Fe/Cd 5c1A | 5 | A | 6 | 48 | 24 |
| Fe/Zn or Fe/Cd 5c1B | B | 12 | 72 | 36 | |
| Fe/Zn or Fe/Cd 5c2C | C | 48 | 120 | 72 | |
| Fe/Zn or Fe/Cd 5c2D | D | 72 | 168 | 96 | |
| Fe/Zn or Fe/Cd 5Bk | Bk | 12 | -- | -- | |
| Fe/Zn or Fe/Cd 8c1A | 8 | A | 6 | 96 | 48 |
| Fe/Zn or Fe/Cd 8c1B | B | 24 | 120 | 72 | |
| Fe/Zn or Fe/Cd 8c2C | C | 72 | 168 | 120 | |
| Fe/Zn or Fe/Cd 8c2D | D | 96 | 192 | 144 | |
| Fe/Zn or Fe/Cd 8Bk | Bk | 24 | 120 | 72 | |
| Fe/Zn or Fe/Cd 12c1A | 12 | A | 6 | 144 | 72 |
| Fe/Zn or Fe/Cd 12c1B | B | 24 | 192 | 96 | |
| Fe/Zn or Fe/Cd 12c2C | C | 72 | 240 | 144 | |
| Fe/Zn or Fe/Cd 12c2D | D | 96 | 264 | 168 | |
| Fe/Zn or Fe/Cd 12Bk | Bk | 24 | 192 | 96 | |
| Fe/Zn or Fe/Cd 25c1A | 25 | A | data not available | ||
| Fe/Zn or Fe/Cd 25c1B | B | ||||
| Fe/Zn or Fe/Cd 25c2C | C | ||||
| Fe/Zn or Fe/Cd 25c2D | D | ||||
| Fe/Zn or Fe/Cd 25Bk | Bk | ||||
|
a For zinc coatings see classification code in
ISO 2081.
For cadmium coatings see classification code in
ISO 2082. b For designation code systems, see clause 13. c Chromate treatments are designated in table B.2. d Low coating thicknesses impair chromate conversion performance. |
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| Class | Designation | Type | Typical appearance | Corrosion protection |
|---|---|---|---|---|
| 1 | A | Clear | Transparent, clear, sometimes with a bluish tinge | Slight, for example against staining during handling or against high humidity in mildly corrosive conditions |
| B | Bleached | Transparent with slight iridescence | ||
| 2 | C | Iridescent | Yellow iridescent | Considerable, including protection against certain organic vapours |
| D | Opaque | Olive green shading to brown or bronze | ||
| Bka | Black | Black with slight iridescence | Different degrees of corrosion protection | |
| NOTE: This table is modified from
ISO 4520:1981 by the addition
of black treatment. a Black coatings in addition to types A to D possible. |
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| Designation code for coatingsa (system Bb) | First appearance of red rust on significant surfaces | ||||
|---|---|---|---|---|---|
| Copper or copper alloy base | Ferrous material base | Neutral salt spray test (NSS)e | Copper- accelerated acetic acid salt spray test (CASS) | ||
| Nickel c | Nickel + chromium c,d | Nickel c | Nickel + chromium or copper + nickel + chromium c,d | ||
| Cu/Ni 3b | Cu/Ni 3b Cr r | Fe/Ni 5b | Fe/Ni 5b Cr | -- | --f |
| Cu/Ni 5b | Cu/Ni 5b Cr r | Fe/Ni 10b | Fe/Ni 10b Cr Fe/Cu 10 Ni 5b Cr r |
12h | --f |
| Cu/Ni 10b | Cu/Ni 10b Cr r | Fe/Ni 20b | Fe/Ni 20b Cr Fe/Cu 20 Ni 10 b Cr r |
48h | --f |
| Cu/Ni 20b | Cu/Ni 20b Cr r | Fe/Ni 30b | Fe/Ni 30b Cr | -- | 8h |
| Not recommended | Cu/Ni 30d Cr r | Not recommended | Fe/Ni 40d Cr | -- | 16h |
|
a For nickel coatings see classification code in
ISO 1456:1988.
b For designation code systems see clause 13. c "b" refers to bright nickel deposits and "d" refers to duplex nickel deposits. d "r" refers to regular (conventional) chromium, minimum thickness 0,3 µm. e Neutral salt spray tests (NSS) are not usually specified for Ni/Cr coatings. f Performance times in copper-accelerated acetic acid salt spray test (CASS) for the lower grades of coating would be too short to be meaningful. |
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