| Passivate
Services
A
process designed to remove foreign metals from the
surface of stainless and corrosion resistant steels
and to promote natural tendency of surface to oxidize.
Does not change the appearance of the base metal.
Process purifies surface and therefore improves corrosion
resistance.
|
| Spec. |
Thickness |
Comment |
| AMS-P-35 |
No
dimensional
change |
| Type
II |
Medium
temperature with sodium dichrominate. |
| Type
VI |
Low
temperature |
| Type
VII |
Medium
temperature |
| Type
VIII |
Medium
temperature with high concentration of nitric acid.
|
| |
24
hour humidity test required. Salt spray test may be
required, if specified, in addition to humidity test. |
| Spec. |
Thickness |
Comments |
| ASTM-A-967-99el** |
|
**Alternate
spec to supercede QQ-P-35. In addition to passivate
using Nitric acid (and Sodium Dichromate), this ASTM
also introduces passivation using Citric acid which
at the present time, Alexandria Metal Finishers does
not perform.
|
| |
|
Nitric
Acid
(Vol. %) |
Sodium
Dichromate
(Weight %) |
| Nitric
1 |
120°-130°F
20 min. |
20-25 |
2.5
+ 0.5 |
| Nitric
2 |
70°-90°F
50 min. |
20-45 |
none |
| Nitric
3 |
120°-140°F
20 min. |
20-25 |
none |
| Nitric
4 |
120°-130°F
30 min. |
45-55 |
none |
| Nitric
5 |
As
required |
As
required to pass tests |
| Practice
A |
All
tests
need not be
performed
unless
specified. |
Water
Immersion Test |
| Practice
B |
High
Humidity Test |
| Practice
C |
Salt
Spray Test |
| Practice
D |
Copper
Sulfate Test |
| Practice
E |
Potassium
Ferricyanide - Nitric Test |
