5. Surface Treatment for Stainless Steels and Nickel-Chromium Alloys
A. No surface treatment is required after rework on stainless steel and nickel-
chromium alloys. Refer to par. 7 for plated alloys. Stainless steel requires
passivation after rework.
6. Surface Treatment for Titanium Alloys
A. No surface treatment is required after rework on titanium alloys. Apply
original finish. Refer to par. 7 for plated alloys.
7. Surface Treatment for Cadmium Plated or Phosphated Metals
CAUTION: STEEL PARTS HEAT-TREATED ABOVE 180 KSI ARE SUBJECT TO HYDROGEN EMBRIT-TLEMENT. LOW HYDROGEN EMBRITTLEMENT PLATING MUST BE USED. REFER TO 20-42-01,20-42-02 AND 20-42-10 OF THE BOEING STANDARD OVERHAUL PRACTICES MAN-UAL FOR PLATING PROCEDURES.
A. Rework of cadmium plated surfaces indicates a break in the plated surface
and exposure of the base metal. Surface treatment should therefore be
replating of the base metal. Use low hydrogen embrittlement stylus cadmium
plating (20-42-10 of the Boeing Standard Overhaul Practices Manual). Major
rework requires stripping and replating.
Volume 1
20-50-00
Page 7
OCT 01/01
CORROSION PREVENTION MANUAL
GENERAL INFORMATION STANDARD TREATMENT METHODS
B. Phosphate coating is applied to the cadmium plating on alloy steels heat-
treated to 180 ksi and above that are partially cadmium plated. Surface
treatment involves use of phosphoric acid to the cadmium plating. Refer to
par. 10.C.(1) of 20-40-00 for treatment procedure. If cadmium plating is
broken, plate per par. A. before coating.
C. Phosphate coating of alloy steels heat-treated to 180 ksi and below is
applied instead of plating to inaccessible areas such as inside of tubings,
sharp beads, etc. Coating procedure of the base metal is the same as
described in par. 10.C.(1) of 20-40-00.
Material Variable Make-Up [1] Control
Alodine Concentration 1.2 oz/gal 1.0 to 3.0 oz/gal
1200 pH 1.5 to 2.1[2]
Temperature 60 to 100F
Alodine Concentration 1.2 oz/gal 1.0 to 3.0 oz/gal
1200S pH 1.3 to 1.8 [2]
Temperature 60 to 100F
[1] After make-up, allow the solution to set undisturbed for 24 hours before
using. The small amount of precipitate which forms will not bother the
coating process.
[2] Higher concentrations will tend to have lower pH values, which will rise
with age or use, generally leveling off with the ranges stated. The pH may
中國航空網 m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：757 防腐手冊 CORROSION PREVENTION MANUAL 第二冊 一般信息(47)
