ASTM B481-68(2013)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B481 − 68 (Reapproved 2013)
Standard Practice for
Preparation of Titanium and Titanium Alloys
for Electroplating
This standard is issued under the fixed designation B481; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Full utilization of the light weight and high strength of titanium is prevented by the tendency it has
to gall and seize and by its lack of corrosion resistance at elevated temperatures. Frequently these
limitations can be overcome by electrodepositing upon the titanium a metal with satisfactory
properties. Titanium is an active metal that rapidly forms an adherent oxide coating in the presence of
oxygen and water. This coating prevents the application of adherent electrodeposits by the more
familiar preparative processes. For this reason, the special processes described in this practice were
developed.
1. Scope 3. Reagents
1.1 This practice describes processes that have been found 3.1 PurityofReagents—Allacidsandchemicalsusedinthis
to be successful in producing adherent electrodeposits of good practice are technical grade.Acid solutions are based upon the
quality on titanium and certain titanium alloys. Not all of the following assay materials (Warning—Use hydrofluoric acid
processes that have been reported as successful are described, with extreme care.):
but rather three basic ones that have had the widest use. A
Hydrochloric acid 37 mass %, density 1.184 g/mL
Hydrofluoric acid 60 mass %, density 1.235 g/mL
rather complete listing of the published work on electroplating
Hydrofluoric acid 71 mass %, density 1.260 g/mL
ontitaniumisgiveninthelistofreferenceswhichappearatthe
Hydrofluoric acid 100 mass %, density 1.0005 g/mL
end of this practice.
Nitric acid 69 mass %, density 1.409 g/mL
1.2 This standard does not purport to address all of the
3.2 Purity of Water—Use ordinary industrial or potable
safety concerns, if any, associated with its use. It is the
water for preparing solutions and rinsing.
responsibility of the user of this standard to establish appro-
4. Process No. 1
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For a specific
4.1 Cleaning—Remove oil, grease, and other soil by appro-
hazard statement, see 3.1.
priate conventional processes such as vapor degreasing, alka-
line cleaning, grinding, or blasting.
2. Referenced Documents
4.2 Activating—Activation may be done by chemical or
2.1 ASTM Standards:
electrochemical etching or liquid abrasive blasting. It is pos-
B343 Practice for Preparation of Nickel for Electroplating
sible that all three processes will work equally well on pure
with Nickel
titaniumandallcommonalloys;however,onlythoseforwhich
each process has been demonstrated to be successful are given
This practice is under the jurisdiction of ASTM Committee B08 on Metallic here. The suitability of a process for an alloy not listed should
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.02 on
be experimentally determined before committing production
Pre Treatment.
parts.
Current edition approved Dec. 1, 2013. Published December 2013. Originally
4.2.1 Chemical Etch:
approved in 1968. Last previous edition approved in 2008 as B481–68 (2008). DOI:
10.1520/B0481-68R13.
4.2.1.1 The following procedure is suitable for commer-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
cially pure titanium and for 6Al-4V, 4Al-4Mn, and 3Al-5Cr.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.2.1.2 Pickle—Immerse in the following solution, at room
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. temperature, until red fumes are evolved:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B481 − 68 (2013)
chemical attack of the metal is stopped as evidenced by the
HF (60 mass %) 1 volume and
HNO (69 mass %) 3 volumes
cessation of gassing. Then reduce the current to the operating
value and etch anodically at 5.4 A/dm for 15 to 30 min.
4.2.1.3 Rinse.
4.2.1.4 Etch—Immerse in the following aqueous solution
HF (anhydrous) 15 mass %
H O 6 mass %
for20min(Notethataspecialformulationisrecommendedfor 2
Ethylene glycol 79 mass %
3Al-5Cr alloy).
Temperature 55 to 60°C
Standard 3Al-5Cr
5.2.4.1 The formulation in 5.2.4 is equivalent to the follow-
Na Cr O ·2H O 250 g/L 390 g/L
2 2 7 2
HF (60 % mass) 48 mL/L 25 mL/L ing volumetric formulation.
Temperature 82 to 100°C 82 to 100°C
HF (71 mass %) 19 volumes and
Ethylene glycol 81 volumes
NOTE 1—For platinum electroplating on commercially pure titanium,
etching may be done by immersion for 5 min in hot (94°C min)
5.2.4.2 The water content must not be too high; therefore,
concentrated hydrochloric acid followed by rinsing and platinum electro-
3 less concentrated grades of hydrofluoric acid cannot be substi-
plating (1)
tuted for the 71 % grade. The solution or part should be mildly
4.2.2 Rinse.
agitated. The cathodes may be carbon, nickel, copper, or other
4.2.3 Electroplate—Electroplate with chromium, with cop-
materials not attacked by the solution.
per from an acid bath, or with nickel from either a Watts or
5.2.4.3 Remove the part while the current is still on.
sulfamate bath, or deposit nickel in an autocatalytic bath. If a
5.2.4.4 Excessive current densities will produce electropol-
deposit of some metal other than these three is desired, first
ishing and inadequate current densities will permit local
apply a nickel coating with a minimum thickness of 1 µm
chemical attack. Both conditions will result in lack of adhesion
followed by the desired final metal.
of the electroplating.
4.2.4 Heat Treat:
5.2.5 Rinse.
4.2.4.1 The adhesion of the electrodeposit is mechanical
5.2.6 Electroplate—Electroplate with copper from an acid
and, therefore, although of a relatively high order of
bath or copper from a cyanide bath preceded by a cyanide
magnitud
...