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ZINCHROMATE OLIVE GREEN173
OLIVE
GREEN CHROMATE CONVERSION PROCESS
This process is specially
designed to produce a heavy olive green chromate
conversion coating on cyanide as well as chloride
zinc electroplated parts. The chromated film produced by
the process, afford
very high corrosion resistance of over 16 hours
in salt spray test. This is an ideal product for aircraft and
automobiles parts, electrical appliances and defence
applications where high
corrosion resistance is required.
The process is very convenient
to use, have long life and require only
routine maintenance.
It can be used in both manual
automatic rack
and basket operations and may be
used in barrel operations.
OPERATING CONDITIONS :
Zinchromate
Olive Green - 173
80 - 120 ml/lit.
Temperature
25 - 40*c
Ph
(electrometric)
0.8-1.4
Time
30 - 120 seconds
Agitation
Component movement
Or Air
EQUIPMENT :
PVC
or HDPE plastic containers are suitable.
MAKE UP :
1.
Fill the clean tank with two third full of clean water.
2.
Add required
quantity zinchromate olive green-173 and stir
the solution well.
3.
Fill the
tank to
operating volume and
stir to
ensure through mixing of the operating solution.
PROCESS SEQUENCE :
1.
Zinc plating with minimum 7 micron thickness.
2.
Cold water rinse twice.
3.
Zinchromate olive green - 173 process dip.
4.
Cold water rinse twice.
5.
Dry.
MAINTENANCE :
Replenishment
additions of zinchromate olive green-173 solution are evidenced
by change in colour of the processed parts and
by increasing in ph or by longer immersion time required
to produce
acceptable colour. Regular addition of 173 stock solution
should be made
on visual observation of parts being processed,
by ph
control or by
speling analytical
measures. Normally 1 litre
of 173 concentrated
solution can be able
to produced acceptable
colour on 120-150 sq.ft. Of treated area of processed parts.
This consumption may
very according to the treatment time, shape
and size of articles and drag out losses.
ANALYTICAL CONTROL :
5 ml Pipette
10 ml Measuring
Cylinder
50 ml Burette
250 ml
Erlenmeyer Flask
0.1 n
Sodium Thio Sulphate solution
25 %
Sulphuric Acid solution
10 % Potassium
Iodide solution
1 %
Starch solution
Sodium fluoride
PROCEDURE :
Pipette
2.5 ml of the solution into a 250 ml
erlenmeyer flask.
Add 10 ml 25 % sulphuric acid
solution, 1.0 gm sodium
fluoride and 15 ml of 10 % potassium iodide solution.
Swirl and keep it in dark for 5 minute.
Titrate with
0.1 n sodium thiosulphate
solution to a light
yellow colour, add 2 ml
of 1
% starch solution and
continue the titration until a blue
black colour
disappears.
CALCULATIONS :
ML Of 0.1 N SODIUM THIOSULPHATE Used X 4.5 =____________
ml/Ltr Of 173.
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