(e)
Immersion Application. Immerse part in Iridite solution for 1 to 6
minutes until the desired coating is obtained. The use of test sam-ple is recommended to ascertain the correct immersion time.
NOTE: The Iridite solution will accumulate sludge. In no case shall the
depth of the sludge be allowed to reach a point where it touches
the work.
CAUTION: DO NOT ATTEMPT TO BRUSH OUT THE SOLUTION LIKE PAINT AS SOFT
COATING WILL SCRATCH OR TEAR WHILE STILL FRESH.
(f)
Manual Application. Apply the Iridite solution liberally and evenly
with a nylon brush, cotton swab, cellulose sponge or white blotting
paper. Maintain a continuos wet film for 3 to 6 minutes if a yellow
coating is required and from 30 seconds to 3 minutes if a clear
coating is required.
(g)
Remove excess Iridite by thoroughly flushing with clean water, then
allow to dry at ambient temperature. Force air dry if possible.
(h)
All powder visible on parts after treatment shall be wiped off the
dry parts with clean dry rags.
(i)
Apply original finish.
(j)
Remove masking and protective covering.
3. Surface Treatment for Magnesium Alloys
A. General. Magnesium alloys are highly susceptible to corrosion when the metal
surface is exposed without a protective finish. An oxide-carbonate film will
normally form on an exposed magnesium alloy surface but this surface pro-vides very little protection against corrosion. A proper protective finish
is therefore required.
B. Surface Treatment. All magnesium alloy surfaces that have been reworked per
20-40-00 or applicable methods in Part 3 shall be cleaned and treated with a
conversion coating. The coating materials convert the magnesium alloy sur-face into an inhibitive passive layer on the base metal that resists corro-sion. This coating is applied using the brush-on technique.
Volume 1
20-50-00
Page 5 OCT 01/01
CORROSION PREVENTION MANUAL
GENERAL INFORMATION STANDARD TREATMENT METHODS
(1)Solution Preparation
(a) The chemicals used for the solution are:
Chromic Acid (Cr03)
Calsium Solfate (CaS04.2H20)
(b)
The solution shall be prepared and stored in polyethylene or glass
containers.
(c)
Prepare the solution using the following proportions and control.
The chemicals shall be added to the water in the order given below.
Chromic Acid 1.3 oz/gal
Calcium Sulfate 1 oz/gal
Distilled Water to make 1 gal
pH 1.2-1.6
NOTE: Adjust pH with additions of sodium hydroxide or sulfuric acid as
required.
(d)
Vigorously stir for 15 minutes to ensure that the solution is satu-rated with calcium sulfate.
(e)
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