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ISO9001:
2000
Used
Plating |
The following
is a comprehensive listing of finishing specifications, not all
are done by TCMF.
To find a
key term or word press CTRL and F
Anodize
(MIL-A-8625E)
Coatings can be colored with a large variety of
dyes and pigments. Conventional Types I, IB
and II are intended to improve surface corrosion
protection under severe service conditions or as a
base for paint systems. Due to thinness of
coating, Types I and IB coatings should be used on
fatigue critical components. Type IC and IIB
coating provide non-chromate alternatives to Type
I and IB where corrosion, resistance, paint
adhesion and fatigue resistance is required. Prior
to dying or sealing, coatings shall meet weight
requirements in Table I of specification. Specify class of anodic coating and any special
sealing requirements.
Type
I - Chromic Acid
Type I: (.00002"-
.0007" thickness) Chromic acid conventional
anodizing. Unless otherwise
specified shall not be applied to aluminum
alloys with over 5% copper, 7.0% silicon or
total alloying constituents over 7.5%.
Type IB: (0.0002" -
.0007") Low voltage chromic acid anodizing
(22 V 2V)
Type IC: (0.00002" -
.0007") Mineral or mixed mineral/organic
acid anodizes. Provides a
non-chromate alternative for Type I and IB
coatings.
Class 1: Non-dyed.
Class 2: Dyed, Specify color
on contract.
Type
II - Sulfuric Acid
Type II: (.0007" -
.0010") Conventional sulfuric anodizing.
Class 1: Non-dyed.
Class 2: Dyed, Specify color
on contract.
Type IIB:
(.00002"-.0007") Thin sulfuric
anodizing for use as non-chromate alternatives
for Type I and IB coatings.
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Type
III - Hard
Anodize
Color will vary from light tan to
black depending on alloy and thickness. Can
be dyed in darker colors depending on thickness.
Coating penetrates basis material as much as it
builds up. The term "thickness" includes
both the buildup and penetration. Provides very
hard, ceramic like coating. Abrasion
resistance will vary with alloy and thickness of
coating. Good dielectric properties. Do not seal coatings where the main function is to
obtain maximum abrasion or wear resistance. When used for exterior applications requiring
corrosion resistance but permitting reduced
abrasion resistance, the coating shall be sealed
(boiling deionized water or hot 5% sodium
dichromate solution, or other suitable chemical
solutions). Abrasion resistance for unsealed
coatings tested by method 6192 of FED-STD-141
using CS-17 wheels with 1000 gm load. The
anodic coating shall have a maximum wear index of
3.5 mg/1000 cycles on aluminum alloys having a
copper content of 2 percent or higher. The
wear index for all alloys shall not exceed 1.5
mg/1000 cycles.
Type III: As specified on
drawing. If not specified nominal
thickness shall be 0.002"
Class 1: Not dyed or
pigmented.
Class 2: Dyed. (Specify
color on contract).
Process can be controlled to
very close thickness tolerances. Where
maximum serviceability or special processes
are required, consult metal finisher for best
alloy choice. Thick coatings (over
.004") will tend to break down sharp
edges. Typical applications: hydraulic
cylinders wear surfaces, actuating cams, etc.
Can be used as an electrical insulation
coating. "Flash" hard anodize
may be used instead of conventional anodize
for corrosion resistance and may be more
economical in conjunction with other hard
anodized areas.
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Black
Chrome
(MIL-C-14538C)
(Approximately .0002"
thickness) A hard, non-reflective,
abrasion-resistant, heat and corrosion resistant
coating. Black Chromium has poor
throwing power, and conforming anodes are
necessary for intricate shapes. Apply after
heat treating and all mechanical operations are
performed. The Black Chrome surface may be
waxed or oiled to darken the surface. Coating provides limited corrosion protection, but
added protection can be obtained by specifying
underplate such as nickel. Color is a dull
dark gray, approaching black. It shall
approximate color plate 37038 of Federal Standard
Number 595. Steel parts with Rockwell
hardness in excess of Rc 40 shall be stress
relieved prior to plating by baking one hour or
more at 300 to 500 F and baked after plating 375
25 for 3 hours minimum for hydrogen embrittlement
relief.
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Black
Oxide Coating
(MIL-C-13942C)
Black oxide coating causes no
dimensional change. It is a uniform black
coating for ferrous metals. Used mostly as a
decorative coating. Only very limited
corrosion protection, under mildly corrosive
conditions. For moving parts which cannot tolerate
the dimensional change of a more
corrosion-resistant finish, Black oxide
coatings should normally be given a supplementary
treatment (i.e., oil displacement per Mil-C-16173
Grade 3 or protective treatments per Mil-C-16173).
For decorative applications Black Oxide can be
used to decrease light reflection.
Class 1: Alkaline oxidizing.
For wrought iron, cast and malleable irons,
common carbon, and low alloy steels.
Class 2: Alkaline oxidizing.
Use on certain corrosion resistant steel alloys
tempered at less than 900F
Class 3: Fused salt oxidizing.
For corrosion resistant steel alloys which are
tempered at 900F (482C) or higher.
Class 4: Alkaline oxidizing.
For all other corrosion resistant steel alloys.
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Cadmium
(QQ-P-416F)
Bright silvery white. Supplementary treatments for Type II can be
golden, iridescent, amber, black, olive drab, or
clear. Corrosion resistance is very good,
especially with Type II finish. The cadmium
plating shall be smooth, adherent, uniform in
appearance, free from blisters, pits, nodules,
burning, and other defects when examined visually
without magnification. Luster: Unless
otherwise specified, the use of brightening agents
in plating solution is prohibited on components
with a specified heat treatment of 180 Ksi minimum
tensile strength (HRc 40) and higher. Either a
bright (not caused by brightening agents) or dull
luster shall be acceptable. Brighteners may
be used with alloys listed in paragraph 3.2.8.
Parts which have been machined, ground, cold
formed, or cold straightened after heat treatment
shall receive stress relief bake in accordance
with table I or Ia of specification prior to shot
peening, cleaning or plating. All parts
shall be baked within 4 hours of plating as
specified in tables I of this specification.
Baking on types II and III shall be done prior to
application of supplementary coatings.
Type I: As plated.
Type II: Supplementary chromate
treatment. Type II plating shall not show
white corrosion products of cadmium, pitting, or
basis metal corrosion products at the end of 96
hours (20%) salt spray exposure per table III of
this specification. Unless otherwise
specified, chromate treatment required for
Type II is distinctly colored iridescent bronze
to brown including olive drab, yellow and forest
green.
Type III: Supplementary
phosphate treatment. Phosphate treatment
required for
Type III shall conform to Type I
of TT-C-490. Type III is used as a paint base.
Class 1: .0005" minimum
thickness
Class 2: .0003" minimum
thickness, additional thickness requirements
are given in paragraph 3.3.1 amendment 2, of
this specification.
Class 3: .0002" minimum
thickness.
For Class 1 and 2 the minimum
cadmium thickness requirement shall be met
after the supplementary treatment.
Excellent for plating stainless
steels that are to be used in conjunction with
aluminum to prevent galvanic corrosion.
Cadmium deposition should not be
used when an alternate process meets the
performance requirements of this specification.
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Chemical
Films
(MIL-C-5541E)
Materials qualified produce
coatings that range in color from clear to
iridescent yellow or brown. Inspection
difficulties may arise with clear coatings because
visual inspection does not always reveal the
presence of a coating.
Class 1A: Chemical
conversion coatings are intended to provide
corrosion prevention when left unpainted as well
as to improve adhesion of paint finish systems
on aluminum and aluminum alloys. May be
used on tanks, tubing, and component structures
where paint finishes are not required for the
exterior surfaces but are required for the
interior surfaces.
Class 3: Chemical
conversion coatings are intended for use as a
corrosion preventative film for electrical and
electronic applications where lower resistant
contacts, relative to Class 1A coatings, and
anodic coatings in accordance with Mil-A-8625,
are required. The primary difference
between a Class 1A and a Class 3 coating is
thickness.
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Chemical
Finish: Black
(MIL-F-495E)
A uniform black corrosion
retarding coating for copper. Coating
has no abrasion resistance. Used to impart
black color to and for gloss reduction purposes on
copper-alloy surfaces other than food service and
water supply items. Also as a base for
subsequent coatings such as lacquer, varnish, oil,
and wax.
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Chrome
(QQ-C-320B)
Excellent hardness (Rc 68-74),
wear resistance and erosion resistance. Has
low coefficient of friction, and is resistant to
heat. In addition to above properties, can
be rendered porous for lubrication purposes.
All coated steel parts having a hardness of
Rockwell C 36 and higher shall be baked after
plating at minimum of 375 25F per the
following schedule:
Tensile Strength (Ksi)Time (At
Temperature Hours)
160-1803
181-220 8
221 and above 12
All Class 2 plated parts designed
for unlimited life under dynamic loads shall be
shot peened per MIL-S-13165 or MIL-R-81841 prior
to plating.
Type I: Bright
Type II: Satin
Class 1: Corrosion protecting
plating (.00001" minimum thickness on all
visible surfaces).
Class 2: Engineering plating
(.002 minimum thickness unless otherwise
specified).
Class 2a: Plated to
specified dimensions or processed to specified
dimensions after plating.
Class 2b: Parts below Rc
40 and subject to static loads or designed for
limited life under dynamic loads.
Class 2c: Parts below Rc 40
and designed for unlimited life under dynamic
loads.
Class 2d: Parts have hardness
of Rc 40 or above and subject to static loads
or designed for limited life under dynamic
loads.
Class 2e: Parts have hardness
of Rc 40 or above and are designed for
unlimited life under dynamic loads.
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Copper
(MIL-C-14550B)
Copper in color and matte to a
very shiny finish. Good corrosion
resistance when used as an undercoat. A
number of copper processes are available, each
designed for a specific purpose;
Brightness (to eliminate the need
for buffing).
High speed (for electroforming).
Fine grain (to prevent
casehardening), etc. All steel parts having a
hardness of Rockwell C35 and higher shall be
baked at 19114C (37525) for 24 hours
within 4 hours after plating to provide hydrogen
embrittlement relief. Plated springs and other
parts subject to flexure shall not be flexed
prior to the baking operations.
Class 0: (Unless otherwise
specified .001-.005") For heat treatment
stop-off.
Class 1: (.001 minimum
thickness) For carburizing and decarburizing
shield, also plated through printed circuit
boards.
Class 2: (.0005"
minimum thickness) As an undercoat for nickel
and other plating.
Class 3: (.0002"
minimum thickness) To prevent basis metal
migration into tin (prevents poisoning of
solderability).
Class 4: (.0001"
minimum thickness)
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Dow
(MIL-M-3171C)
Magnesium Processes
#1: Chrome pickle
treatment for magnesium. Color
varies from matte gray to yellow-red. Only
fair corrosion resistance (less than 24 hours
20% salt spray resistance).
#7: A dichromate treatment
for magnesium. Color varies from light
brown to dark brown to gray depending on alloy.
Only fair corrosion resistance (less than 24
hours 20% salt spray resistance).
#9: A galvanic anodize
treatment for magnesium. Produces a dark
brown to black coating. Designed to give a
protective film on alloys which do not react to
Dow No. 7 treatment. Only fair corrosion
resistance (less than 24 hours 20% salt spray
resistance).
Type I: Removes metal
(Approximately .0006" for wrought material,
less for castings). No dimensional change.
Used mainly for protecting magnesium during
shipment, storage, and machining. Can be
used as a paint base. Note: Must remove
Type I coating before applying Type III and Type
IV treatments. Good paint base and
protective qualities for all magnesium alloys
except EK30A, EK41A, EZ33A, HK31A and M1A.
Type III: (Note)
Pre-cleaning and pickling may result in
dimensional changes due to metal loss.
Type IV: Causes no dimensional
change. Can be used as a paint base, and
is suitable to all magnesium alloys. Used
where optical properties (black/non-reflective)
are required on close tolerance parts (camera
parts, laser components, telescopes, etc.)
Note: Pre-cleaning and pickling may result
in dimensional changes due to basis material
loss.
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Electroless
Nickel
(Mil-C-26074,
ASTM-B-733, AMS-2404C, AMS-2405B, AMS-2433B)
Coatings typically used to provide
a hard-ductile, wear-resistant and
corrosion-resistant surface for operation in
service temperatures up to 1000F (538C). Electroless nickel provides uniform build-up on
complex shapes.
AMS 2404C: Unless otherwise
specified, deposit coating directly on the basis
metal without a flash coating of other metal.
AMS 2405B: Unless otherwise
specified, deposit coating directly on basis
metal except where parts fabricated from
corrosion resistant steels or alloys where a
"strike" coating of nickel or other
suitable metal is required. This
specification is for low phosphorus electroless
nickel.
AMS 2433B: This type electroless
nickel is typically used to enhance
solderability of surfaces, but usage is not
limited to such applications. Generally,
plating shall be directly on basis metal.
However, aluminum alloys shall be double
zincated per ASTM B253 followed by copper flash.
Corrosion resistant steels, nickel, cobalt
alloys or other basis metals may use nickel or
copper flash undercoat when purchaser permits.
Preparation: Parts having
hardness higher than Rc 40 that have been
machined or ground after heat treatment shall be
stress-relieved before cleaning and plating.
Post-Treatment: Parts
having hardness of Rc 33 and above shall be
baked at 375 F 15 for 3 hours minimum.
If such temperature is deleterious to parts,
bake at 275F 15 for 4 hours minimum.
Electroless Nickel, Low
Phosphorus Preparation: See above. Note:
If permitted on drawing, maximum hardness and
wear resistance are obtained by heating parts
for 30 minutes or more, preferably in an inert
atmosphere, at 750 F 15, except that
aluminum parts shall be baked at 450 F 15
for 4 hours minimum. If such baking
temperature and time is not specified, bake at
375 F 15 for 3 hours minimum. Note:
if this treatment could be deleterious to parts
or assemblies, bake at 275 F for 5 hours
minimum.
Preparation: All
fabrication operations shall be completed prior
to plating.
Post-treatment: Cold worked or
heat treated parts and parts made from aluminum
alloys and other parts requiring special thermal
treatment shall be post treated as agreed upon
by purchaser and vendor. Other plated
parts shall be baked at 675 15 F for 90
10 minutes within 4 hours after plating.
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Electropolishing
Typical material removal <
.0002" per surface, unless otherwise
specified. Process electrochemically removes
material, therefore diminishes scratches, burrs
and unwanted sharp edges from most metals. Electropolishing is most frequently done to
stainless steel, relatively high in both nickel
and chromium content (300 and 400 series).
Finishes from satin to mirror-bright are produced
by controlling time, temperature, current, bath
make-up or singularly or in combinations. Surface appearance results is also dependent on
pre-process condition. Process is not recommended
for close tolerance surfaces.
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Gold
(MIL-G-45204C)
Yellow to orange color depending
on proprietary process used. Ranges from
matte to bright finish depending on basis material
and type, grade and class of gold used. Brightness of underplating will also affect
appearance. Excellent corrosion resistance,
and has high tarnish resistance. Provides low
contact resistance, and is an excellent conductor.
Gold has excellent solderability. If the
hardness grade for the gold coating is not
specified, Type I shall be furnished at hardness
Grade A, and Type II shall be furnished at
hardness Grade C. For soldering, a thin,
high purity soft gold coating is preferred. A minimum thickness of .000050 inch and a maximum
thickness of .00010 inch shall be plated.
Type I: 99.7% gold minimum
(Grades A, B, or C).
Type II: 99.0% gold minimum
(Grades B, C, or D)
Type III: 99.9% gold minimum
(Grade A only).
Grade A: 90 Knoop maximum.
Grade B: 91-129 Knoop.
Grade C: 130-200 Knoop.
Grade D: 201 Knoop and over.
Class 00: .00002"
minimum thickness
Class 0: .00003"
minimum thickness
Class 1: .00005"
minimum thickness
Class 2: .00010"
minimum thickness
Class 3: .00020"
minimum thickness
Class 4: .00030"
minimum thickness
Class 5: .00050"
minimum thickness
Class 6: .00150"
minimum thickness
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Lubricant,
Solid Film
(MIL-L-46010D)
This specification establishes the
requirements for three types of heat cured solid
film lubricant that is intended to reduce wear and
prevent galling, corrosion and seizure of metals.
Compliance: all items must meet Sections 3
and 5 of spec. For use on aluminum, copper,
steel, stainless steel, titanium, and chromium and
nickel bearing surfaces. Thickness for all
types: 0,008mm - 0,013mm No single reading less
than 0,005mm or greater than 0.018mm
Type I: A cure temperature of
150 15C and endurance life of 250 minutes.
Type II: A cure temperature of
204 15C and endurance life of 450 minutes.
Type III: A low volatile organic
compound (VOC) content lubricant with cure
cycles of 150 15C for one hour an
endurance life of 450 minutes.
Color 1: Natural product color.
Color 2: Black color.
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Magnesium
Anodic Treatment
(MIL-M-45202C)
Coatings range from thin clear to
light gray-green, to thick dark green coatings.
The clear coatings are used a base for subsequent
clear lacquers or paints to produce a final
appearance similar to clear anodizing on aluminum.
The light gray-green coatings are used in most
applications that are to be painted. The thick,
dark green coating offers best combination of
abrasion resistance, protective value and paint
base characteristics. The HAE anodic finish
is probably the hardest coating available for
magnesium. They exhibit stability at high
temperatures and good dielectric strength. Excellent paint base. Requires resin seal or paint
for maximum corrosion protection.
Type I: Light coating.
Class A: (.0002) Tan
coating (HAE)
Grade 1: Without post
treatment (dyed).
Grade 2: (.0003) With
bifluoride-dichromate post treatment
Class C: Light green coating
(Dow #17)
Type II: Heavy coating
Class A: (.0015) Hard
brown coating (HAE)
Grade 1: Without post
treatment
Grade 3: With bifluoride-dichromate
post treatment
Grade 4: With bifluoride-dichromate
post treatment including moist
heat aging.
Grade 5: With double
application of bifluoride-dichromate post
treatment including moist heat aging.
Class D: (.0012) Dark
green coating (Dow #17)
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Nickel
(QQ-N-290A)
There is a nickel finish for
almost any requirement. Nickel can be
deposited soft or hard, dull to bright. The
difference is dependent on process used and
conditions employed in plating. The hardness can
range from 150 - 500 Vickers. Can range in
appearance from matte, light gray (almost white)
to a condition resembling stainless steel. Corrosion resistance is a function of thickness.
Has a low coefficient of thermal expansion. Nickel plating is magnetic.
All steel parts
having a hardness of Rc 40 or greater require a
post bake at 375F 25 for 3 hours minimum.
Note: All steel parts having a tensile
strength of 220,000 or greater shall not be nickel
plated without specific approval of procuring
agency.
Class 1: For corrosion
protection. Plating shall be applied over
an underplating of copper or yellow brass on
zinc and zinc based alloys.
In no case shall the copper
underplate be substituted for any part of the
specified nickel thickness.
Class 2: For engineering
applications.
Grade A: .0016"
minimum thickness
Grade B: .0012"
minimum thickness
Grade C: .0010"
minimum thickness
Grade D: .0008"
minimum thickness
Grade E: .0006"
minimum thickness
Grade F: .0004"
minimum thickness
Grade G: .0002"
minimum thickness
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Palladium
(MIL-P-45209B)
A gray, dense deposit, good for
undercoats. Minimum thickness shall be
.000050" unless otherwise specified. Good wear characteristics, corrosion resistance
and catalytic properties. Good conductivity.
Steel springs and other steel parts subject to
flexure or repeated impact and of hardness greater
than Rc 40 shall be baked at 375 F 25 for 3
hours minimum after plating.
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Passivate
(QQ-P-35C)
Intended to improve the corrosion
resistance of parts made from austentic, ferritic
and corrosion-resistant steels of the 200, 300 and
400 series and precipitation hardened
corrosion-resistant steels. 440C
grades may be exempt from passivation treatments
at the discretion of the procuring activity.
The types of passivating are alloy specific:
Type II: Medium temperature
nitric acid solution with sodium dichromate
additive.
Type VI: Low temperature nitric
acid solution.
Type VII: Medium temperature
nitric acid solution.
Type VIII: Medium temperature
high concentration nitric acid solution.
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Phosphate
Coating; Light
(TT-C-490D)
This specification covers cleaning
methods and pre-treatment processes. Type I
is intended as a general all-purpose pretreatment
prior to painting. Type II and IV are
intended primarily for use where metal parts are
to be formed after painting. Type III is
intended for use where size and shape preclude
using type I, II or IV or where items containing
mixed metal components are assembled prior to
treatment. Note: Cleaning material
shall not contain any chemical which is classified
in the Clean Air Act Amendments of 1990 as a Class
I or Class II ozone depleting substance. Light coating for use as a paint base.
Cleaning methods:
Method I: Mechanical or
abrasive cleaning (for ferrous surfaces only).
Method II: Solvent cleaning.
Method III: Hot Alkaline (for
ferrous surfaces only).
Method IV: Emulsion.
Method V: Alkaline derusting
(for ferrous surfaces only).
Method VI: Phosphoric acid.
Type I: Zinc phosphate. Class 1
is a spray application (150-mg/sq. ft. minimum
to 500-mg/sq. ft. maximum).
Class 2A: Immersion or Dip
application (300-mg/sq. ft. minimum to
500-mg/sq. ft. maximum).
Class 2B: Immersion or Dip
application (600-mg/sq. ft. minimum to 1000
mg/sq. ft. maximum).
Type II: Aqueous Iron Phosphate
(35-mg/sq. ft. minimum)
Type III: (.0003-.
0005") Organic pretreatment coating (unless
otherwise specified, MIL-C-8514 of DOD-P-15328).
Type IV: Non-aqueous iron
phosphate. (35-mg/sq. ft. min.)
Type V: Zinc phosphate
(500-mg/sq. ft. min. 1100-mg/sq. ft. max.).
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Phosphate
Coating; Heavy
(DOD-P-16232-F)
A coating for medium and low alloy
steels. Gray to black in color. Intended uses: The "heavy" phosphate
coatings covered by this specification are
intended as a base for holding/retaining
supplemental coatings, which provide the major
portion of the corrosion resistance.
"Light" phosphate coatings used for a
paint base are covered by other specifications
such as TT-C-490. Heavy zinc phosphate coatings
may be used when paint and supplemental oil
coatings are required on various parts or
assemblies. Heavy coating (.0002-.0004"
thickness) is for corrosion and wear resistance.
Type M: Manganese phosphate base
coating (min. 16g/m or 11g/m when specified).
Class 1: Supplementary
preservative treatment or coating, as
specified.
Class 2: Supplementary
treatment with lubricating oil conforming to
MIL-L-3150.
Class 3: No supplementary
treatment.
Class 4: Chemically converted
(may be dyed to color as specified).
With no supplementary coating
or supplementary coating as specified.
Type Z: Zinc phosphate base
coating, (min 11g/m).
Class 1: Supplementary
preservative treatment or coating as
specified.
Class 2: Supplementary
treatment with preservative conforming to
MIL-C-16173. Grade 3 or
MIL-L-3150 as alternative for very small
parts.
Class 3: No supplementary
treatment
Class 4: Same as class above.
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Rhodium
(MIL-R-46085B)
Metallic and similar to stainless
steel in color. Rhodium has excellent
corrosion resistance. Almost as hard as
chromium. Very good abrasion resistance.
Thicker coatings are very brittle. Has high
reflectivity. Parts having hardness of
Rc 33 or above shall be baked at 375F for 3 hours
prior to cleaning for plating. Parts having
hardness of Rc 40 and above shall be baked within
4 hours after plating at 375F for 3 hours.
Type I: Over nickel, silver,
gold, or platinum.
Type II: Over other metals,
requires nickel undercoat.
Class 1: .000002" minimum
thickness. Used on silver for tarnish
resistance.
Class 2: .00001"
minimum thickness.
Class 3: .00002"
minimum thickness. Applications range from
electronics to nose cones or wherever wear,
corrosion resistance, solderability and
reflectivity are important.
Class 4: .00010"
minimum thickness.
Class 5: .00025"
minimum thickness.
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Silver
(QQ-S-365D)
Minimum thickness to be
.0005" unless otherwise specified. White matte to very bright in appearance. Good
corrosion resistance, depending on base metal.
Will tarnish easily. Hardness varies from
about 90 Brinnell to about 135 Brinnell depending
on process and plating conditions. Solderability is excellent, but deteriorates with
age. Excellent electrical conductor. Has excellent lubricity and smear characteristics
for anti-galling uses on static seals, bushing,
etc. Stress relieve steel parts at a
minimum 375F 25F or more prior to cleaning and
plating if they contain or are suspected of having
damaging residual tensile stresses. Embrittlement relieve all steel parts Rc 40 and
above at 375F 25F for 3 hours within 4 hours of
plating. Increasing use in both decorative
and engineering fields, including electrical and
electronic fields.
Type I: Matte.
Type II: Semi-bright.
Type III: Bright. (Not done by
MSI)
Grade A: Chromate post-treatment
to improve tarnish resistance.
Grade B: No supplementary
treatment.
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Tin
(MIL-T-10727C)
Thickness: As specified on
drawing. Color is gray-white in a plated
condition. Has very high luster in fused
condition. Soft and very ductile. Corrosion resistance good. (When specified, coated
items should meet 24-hour 5% salt-spray
requirement.) Solderability is excellent. Tin is not good for low temperature applications
(changes structure and loses adhesion when exposed
to temperatures below -40C). If bright
finish is desired specify Bright Tin plate to be
used in lieu of fused tin. Thickness can
exceed that of fused tin and thicker deposits show
excellent corrosion resistance and solderability.
Type I: Electrodeposited, Use ASTM B545 standard specification for
electrodeposited coatings of tin.
Guide:
(.0001- .00023" thickness)
Flash for soldering.
(.0002- .0004" thickness)
To prevent galling and seizing.
(.0003" minimum thickness)
Where corrosion resistance is important.
(.0002 - .0006" thickness)
To prevent formation of case during nitriding.
Type II: Hot dipped. (Not done
by MSI)
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Tin Lead
(MIL-P-81728A)
Unless otherwise specified:
.0003-.0005" thickness. For flow
brightened electronic components .0003"
maximum thickness. Excellent solderability.
Either a matte or bright luster is acceptable.
For electronic components, use only parts with a
matte or flow brightened finish. Tin 50% to 70% by
weight, lead remainder (Unless otherwise
specified)
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Vacuum
Cadmium
(MIL-C-8837B)
Used primarily to provide
corrosion resistance to ferrous parts that are
required to be free from hydrogen contamination
and possible embrittlement. Recommended for use on
steels with hardness 220,000 psi or above. Coating
is applied after all machining, brazing, welding
and forming has been completed. Prior to
coating, all steel parts having suspected residual
stress from machining, cold working or
straightening shall be stress relieved by baking
at 375 25F for 3 hours. Immediately
prior to coating a light dry abrasive blast is
advisable on areas to be coated. Cadmium
coating shall not be used, if service temperature
reaches 450F or higher.
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Zinc
(ASTM-B633)
This specification covers
requirements for electrodeposited zinc coatings
applied to iron or steel articles for corrosion
protection. It does not cover molten
zinc-coated wire or steel sheets. High
strength steels (tensile strength greater than
1700 MPa) shall not be zinc electroplated.
Stress relieve all parts with ultimate tensile
strength 1000 MPa and above at minimum 190C for 3
hours or more before cleaning and plating.
Hydrogen embrittlement relieve all electroplated
parts of 1200 MPa tensile strength or higher by
baking at 190C for 3 hours or more within 4 hours
after electroplating.
Supplementary treatments shall be
in accordance with Recommended Practice B201. Type
IV shall be in accordance with Recommended
Practice D2092.
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Zinc/Nickel
(AMS-2417,
MSI-143 No-Cad)
A proprietary environmentally safe
Zinc/Nickel alloy plating used in many instances
to replace cadmium plating. Corrosion
protection of more than five (5) time that of
conventional zinc plating, two (2) times that of
cadmium and better than diffused nickel-cadmium on
steel with comparable deposit thickness of .0002 -
.0005. The deposit is harder than cadmium
(250 310 Vickers) providing a
more scratch and wear resistant surface. Electrodeposited Zinc-Nickel coatings have an
electrochemical potential of .80 compared with .82
for cadmium and .83 - .87 for aluminum. Less
exfoliation corrosion of aluminum is observed when
bare, untreated aluminum is coupled with
Zinc-Nickel coated steel than when coupled with
cadmium coated steel. MSI-143
No-Cad Zinc-Nickel is not hazardous to human
health and the processing solutions are easily
treated to meet environmental regulations. As with conventional zinc and cadmium coatings, a
chromate film greatly enhances the corrosion
protection provided by the MSI-143
No-Cad deposit. The chromate formulation
varies somewhat from those used for zinc or
cadmium and the color will vary from part to part
and may be mottled or streaked bronze to
blue-violet. MSI-143 No-Cad can also be chromated with black.
MSI-143
No-Cad meets with the requirements of AMS-2417.
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Triple Cities Metal
Finishing Corporation