ASTM B482-85(2003)

Standard Practice for Preparation of Tungsten and Tungsten Alloys for Electroplating

SCOPE
1.1 This practice makes recommendations of several reported practices for electroplating on tungsten and its alloys along with comments as a guide in the selection of a processing method for a given application. Because data on methods and results of evaluation with electroplated coatings on tungsten are limited, a recommendation of one method over another cannot be made.
1.2 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Feb-2003
• ICS: 77.120.99 - Other non-ferrous metals and their alloys
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.02 - Pre Treatment

Relations

• Replaces: ASTM B482-85(1998) - Standard Practice for Preparation of Tungsten and Tungsten Alloys for Electroplating
• Effective Date: 10-Feb-2003
• Replaced By: ASTM B482-85(2008) - Standard Practice for Preparation of Tungsten and Tungsten Alloys for Electroplating
• Effective Date: 01-Aug-2008
• Referred By: ASTM B867-95(2018) - Standard Specification for Electrodeposited Coatings of Palladium-Nickel for Engineering Use
• Effective Date: 10-Feb-2003
• Referred By: ASTM B700-20 - Standard Specification for Electrodeposited Coatings of Silver for Engineering Use
• Effective Date: 10-Feb-2003
• Referred By: ASTM B488-18 - Standard Specification for Electrodeposited Coatings of Gold for Engineering Uses
• Effective Date: 10-Feb-2003
• Referred By: ASTM B905-00(2021) - Standard Test Methods for Assessing the Adhesion of Metallic and Inorganic Coatings by the Mechanized Tape Test
• Effective Date: 10-Feb-2003
• Referred By: ASTM B984-12(2020)e1 - Standard Specification for Electrodeposited Coatings of Palladium-Cobalt Alloy for Engineering Use
• Effective Date: 10-Feb-2003
• Referred By: ASTM B634-14a(2021) - Standard Specification for Electrodeposited Coatings of Rhodium for Engineering Use
• Effective Date: 10-Feb-2003
• Referred By: ASTM B679-98(2021) - Standard Specification for Electrodeposited Coatings of Palladium for Engineering Use
• Effective Date: 10-Feb-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B 482–85 (Reapproved 2003)
Standard Practice for
Preparation of Tungsten and Tungsten Alloys for
Electroplating
This standard is issued under the fixed designation B 482; 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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Because of the high melting point of tungsten, (3410°C) this metal and its alloys are used in
ultra-high-temperature applications. However, tungsten oxidizes readily and the oxides offer little or
no protection to the metal because they melt or sublime below 2200°C.Tungsten has a body-centered-
cubic structure as does chromium. Its coefficient of thermal expansion is 4.3 µm/m · °C; the coefficient
of chromium is 6.1 µm/m · °C, therefore, chromium-coated tungsten offers a reasonable match based
on crystal structure and coefficient of thermal expansion. The effect of hydrogen must be considered
in the design of coating systems for tungsten. Molecular hydrogen when trapped under a coating can
result in failure of the part. Although failure can occur if the adhesion of the coating to the tungsten
is inadequate, failure within the basis metal as rupture at laminations of stringers has been observed
with off-grade tungsten.
1. Scope 2.2 Precleaning:
2.2.1 The need for descaling, solvent cleaning, and alkaline-
1.1 This practice makes recommendations of several re-
soak cleaning of tungsten is dictated by the degree of cleanli-
ported practices for electroplating on tungsten and its alloys
ness of the surface to be coated. Remove gross scale and
alongwithcommentsasaguideintheselectionofaprocessing
surface imperfections by mechanical means. Remove grease
method for a given application. Because data on methods and
and oil by organic solvents. Remove saponifiable and dispers-
results of evaluation with electroplated coatings on tungsten
ible surface dirt by soak cleaning in a hot alkaline cleaner.
are limited, a recommendation of one method over another
2.2.2 Anodic treatment of tungsten surfaces ina5to25
cannot be made.
mass % sodium hydroxide solution at 71 6 6°C and 16 to 25
1.2 This standard does not purport to address the safety
A/dm can be used to remove undesired surface metal.Anodic
concerns, if any, associated with its use. It is the responsibility
etching in a 10 mass % hydrofluoric acid electrolyte at
of the user of this standard to establish appropriate safety and
24 6 3°C and 5.4A/dm can be used to remove light scale and
health practices and determine the applicability of regulatory
undesired surface metal before activation and electroplating of
limitations prior to use.
tungsten.
2. Processes 2.3 Activation and Electroplating—Two alternative meth-
ods are presented below. The selection of one process over the
2.1 The several processes reported for electroplating on
other should be based on preliminary experimentation. Both
tungsten can be classified as either (1) providing as-deposited
procedures produce as-deposited adhesion of electroplated
adhesion of the coatings or (2) depending on diffusion alloy
metals on tungsten.
bonding to provide such adhesion. Appraisal of the relative
2.3.1 Methods 1 —Treat the precleaned tungsten in a hy-
merits of these processes depends on the application for the
drofluoric acid electrolyte (30 6 10 mass % HF) at 24 6 3°C,
coating.
using2to5V,60-Hzac,and2to5A/dm for1to2min.Either
...