ASTM B482-85(2019)
(Practice)Standard Practice for Preparation of Tungsten and Tungsten Alloys for Electroplating
Standard Practice for Preparation of Tungsten and Tungsten Alloys for Electroplating
ABSTRACT
This practice contains two recommendations based on several reported practices for the process selection in electroplating on tungsten and tungsten alloys. Surfaces should be cleaned either by descaling, solvent cleaning, or alkaline soak cleaning before electroplating. Evaluating which of the suggested processes to use is dependent on the application of the produced coating.
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 all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B482 − 85 (Reapproved 2019)
Standard Practice for
Preparation of Tungsten and Tungsten Alloys for
Electroplating
This standard is issued under the fixed designation B482; 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
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
noprotectiontothemetalbecausetheymeltorsublimebelow2200 °C.Tungstenhasabody-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 adhesion of the coatings or (2) depending on diffusion alloy
bonding to provide such adhesion. Appraisal of the relative
1.1 This practice makes recommendations of several re-
merits of these processes depends on the application for the
ported practices for electroplating on tungsten and its alloys
coating.
alongwithcommentsasaguideintheselectionofaprocessing
method for a given application. Because data on methods and 2.2 Precleaning:
results of evaluation with electroplated coatings on tungsten 2.2.1 The need for descaling, solvent cleaning, and alkaline-
are limited, a recommendation of one method over another soak cleaning of tungsten is dictated by the degree of cleanli-
cannot be made. ness of the surface to be coated. Remove gross scale and
surface imperfections by mechanical means. Remove grease
1.2 This standard does not purport to address all of the
and oil by organic solvents. Remove saponifiable and dispers-
safety concerns, if any, associated with its use. It is the
ible surface dirt by soak cleaning in a hot alkaline cleaner.
responsibility of the user of this standard to establish appro-
2.2.2 Anodic treatment of tungsten surfaces ina5to25
priate safety, health, and environmental practices and deter-
mass % sodium hydroxide solution at 71 6 6 °C and 16 to
mine the applicability of regulatory limitations prior to use.
25 A⁄dm can be used to remove undesired surface metal.
1.3 This international standard was developed in accor-
Anodic etching in a 10 mass % hydrofluoric acid electrolyte at
dance with internationally recognized principles on standard-
24 6 3 °C and 5.4 A⁄dm can be used to remove light scale
ization established in the Decision on Principles for the
and undesired surface metal before activation and electroplat-
Development of International Standards, Guides and Recom-
ing of tungsten.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2.3 ActivationandElectroplating—Twoalternativemethods
are presented below. The selection of one process over the
2. Processes
other should be based on preliminary experimentation. Both
2.1 The several processes reported for electroplating on procedures produce as-deposited adhesion of electroplated
tungsten can be classified as either (1) providing as-deposited metals on tungsten.
2.3.1 Methods 1 —Treat
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