ASTM B629-77(2019)
(Practice)Standard Practice for Preparation of Molybdenum and Molybdenum Alloys for Electroplating
Standard Practice for Preparation of Molybdenum and Molybdenum Alloys for Electroplating
SIGNIFICANCE AND USE
2.1 Molybdenum is used in engineering applications where strength and rigidity of component parts are needed, especially at high temperatures. Its good strength at high temperatures, low vapor pressure, and good impact and creep resistance make it attractive for load-bearing items such as turbine blades, mechanical seals, rocket motor parts, heating elements, and electronic devices. Molybdenum, however, is easily oxidized, and the oxides are not protective. The volatility of the oxides above 800 °C can lead, in the case of unprotected parts, to catastrophic oxidation and to losses in dimensions. Electroplated coatings are applied to molybdenum to prevent oxidation, to prevent seizing and galling, and to assist joining by soldering, brazing, and diffusion bonding.
SCOPE
1.1 This practice covers a procedure for preparing molybdenum and its alloys for electroplating. The procedure utilizes techniques, equipment, and chemicals that are common to electroplating. Specialized procedures such as hydrogen heat treatment and fused salt pickling are not included. These and other procedures can be found in the references listed at the end of this practice.
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
- Status
- Published
- Publication Date
- 31-Mar-2019
- Technical Committee
- B08 - Metallic and Inorganic Coatings
- Drafting Committee
- B08.02 - Pre Treatment
Relations
- Effective Date
- 01-Apr-2019
- Effective Date
- 01-Apr-2019
Overview
ASTM B629-77(2019): Standard Practice for Preparation of Molybdenum and Molybdenum Alloys for Electroplating outlines procedures for effective surface preparation of molybdenum and its alloys prior to electroplating. Molybdenum is valued for high strength, rigidity, and resistance to impact and creep at elevated temperatures, making it essential in demanding engineering applications. However, its tendency to oxidize easily-especially above 800 °C-can cause severe deterioration if components are left unprotected. Electroplated coatings provide vital protection, prevent galling, ease joining (soldering, brazing, diffusion bonding), and maintain the integrity of molybdenum parts in challenging environments.
This ASTM standard details common techniques, chemicals, and processes to ensure optimal substrate conditions, but does not include highly specialized methods such as hydrogen heat treatment or fused salt pickling.
Key Topics
Surface Preparation Procedures
The standard prescribes a sequence of treatments for contaminants and oxides removal:- Precleaning: Removal of dirt, grease, and surface contaminants via solvent, emulsion, soak cleaners, and descaling (sodium hydroxide immersion or mechanical finishing like glass bead blasting).
- Cathodic Alkaline Cleaning: Final cleaning using proprietary alkaline solutions to avoid anodic oxidation, typically at 6 V for 30‒60 seconds.
- Electropolishing: Optional improvement of surface finish using sulfuric acid or a sulfuric-phosphoric acid mixture.
- Rinsing: Frequent rinsing (ideally warm water) at each stage to maintain cleanliness.
- Alkaline and Acid Dips: Brief immersions to further prepare surfaces before metal deposition.
- Striking: Initial nickel or chromium electroplating “strike” layers to promote adhesion and prepare for final plating.
Health and Safety Considerations
Users must establish suitable safety, health, and environmental protocols. Addressing regulatory compliance is essential prior to practicing the procedures described in this standard.
Applications
- Aerospace and Power Generation Components: Turbine blades, mechanical seals, and rocket motor parts require superior high-temperature properties and oxidation resistance offered by electroplated molybdenum.
- Heating Elements & Electronics: Electroplated molybdenum is used in high-performance heating elements and electronic devices where durability and solderability are needed.
- Joining Processes: Electroplated finishes facilitate operations like soldering, brazing, and diffusion bonding, essential for fabricating robust assemblies.
- General Engineering: Any high-strength, load-bearing application demanding protection from oxidation, galling, and dimensional loss at elevated temperatures can benefit from compliance with ASTM B629-77(2019).
Implementing the preparation practices outlined in ASTM B629-77(2019) ensures consistent, high-quality electroplating on molybdenum-all critical for the longevity and performance of advanced materials.
Related Standards
- ASTM B254 – Standard Guide for Preparation of Nickel Alloys for Electroplating
Reference for related substrate preparation techniques. - ASTM B322 – Standard Guide for Cleaning Metals Prior to Electroplating
Covers broad procedures used as guidance in this and other standards. - ASTM B579 – Standard Specification for Electrodeposited Coatings of Nickel on Molybdenum
Specifies requirements for nickel coatings on molybdenum substrates. - ISO 4527 – Metallic and other inorganic coatings-Electrodeposited coatings of nickel for engineering purposes
International guidance for nickel coating processes that may be used following preparation.
By adhering to ASTM B629-77(2019), engineers and manufacturers can assure a reliable base for electroplated coatings, maximizing the functional lifespan and performance of molybdenum-based components.
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Frequently Asked Questions
ASTM B629-77(2019) is a standard published by ASTM International. Its full title is "Standard Practice for Preparation of Molybdenum and Molybdenum Alloys for Electroplating". This standard covers: SIGNIFICANCE AND USE 2.1 Molybdenum is used in engineering applications where strength and rigidity of component parts are needed, especially at high temperatures. Its good strength at high temperatures, low vapor pressure, and good impact and creep resistance make it attractive for load-bearing items such as turbine blades, mechanical seals, rocket motor parts, heating elements, and electronic devices. Molybdenum, however, is easily oxidized, and the oxides are not protective. The volatility of the oxides above 800 °C can lead, in the case of unprotected parts, to catastrophic oxidation and to losses in dimensions. Electroplated coatings are applied to molybdenum to prevent oxidation, to prevent seizing and galling, and to assist joining by soldering, brazing, and diffusion bonding. SCOPE 1.1 This practice covers a procedure for preparing molybdenum and its alloys for electroplating. The procedure utilizes techniques, equipment, and chemicals that are common to electroplating. Specialized procedures such as hydrogen heat treatment and fused salt pickling are not included. These and other procedures can be found in the references listed at the end of this practice. 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.
SIGNIFICANCE AND USE 2.1 Molybdenum is used in engineering applications where strength and rigidity of component parts are needed, especially at high temperatures. Its good strength at high temperatures, low vapor pressure, and good impact and creep resistance make it attractive for load-bearing items such as turbine blades, mechanical seals, rocket motor parts, heating elements, and electronic devices. Molybdenum, however, is easily oxidized, and the oxides are not protective. The volatility of the oxides above 800 °C can lead, in the case of unprotected parts, to catastrophic oxidation and to losses in dimensions. Electroplated coatings are applied to molybdenum to prevent oxidation, to prevent seizing and galling, and to assist joining by soldering, brazing, and diffusion bonding. SCOPE 1.1 This practice covers a procedure for preparing molybdenum and its alloys for electroplating. The procedure utilizes techniques, equipment, and chemicals that are common to electroplating. Specialized procedures such as hydrogen heat treatment and fused salt pickling are not included. These and other procedures can be found in the references listed at the end of this practice. 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.
ASTM B629-77(2019) is classified under the following ICS (International Classification for Standards) categories: 77.120.99 - Other non-ferrous metals and their alloys. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM B629-77(2019) has the following relationships with other standards: It is inter standard links to ASTM B629-77(2013), ASTM B905-00(2021). Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM B629-77(2019) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: B629 − 77 (Reapproved 2019)
Standard Practice for
Preparation of Molybdenum and Molybdenum Alloys for
Electroplating
This standard is issued under the fixed designation B629; 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.
1. Scope 3. Procedure
3.1 Precleaning:
1.1 This practice covers a procedure for preparing molyb-
3.1.1 The principles of electroplating on molybdenum are
denum and its alloys for electroplating. The procedure utilizes
techniques, equipment, and chemicals that are common to similar to those of other metals. The surfaces must be free of
dirt, grease, and other foreign matter. Solvent, emulsion, and
electroplating. Specialized procedures such as hydrogen heat
treatment and fused salt pickling are not included. These and soak cleaners are suitable for precleaning to remove gross
surface contaminants. If a molybdenum specimen is subjected
otherprocedurescanbefoundinthereferenceslistedattheend
of this practice. to severe forming operations and retains a carbonaceous
surface layer, descale the part by immersion in a 110 g/L
1.2 This standard does not purport to address all of the
solution of sodium hydroxide at or near boiling, or by
safety concerns, if any, associated with its use. It is the
mechanical finishing. Glass bead blasting can be used to
responsibility of the user of this standard to establish appro-
remove uneven coatings of scale without disturbing the finish
priate safety, health, and environmental practices and deter-
of the metal.
mine the applicability of regulatory limitations prior to use.
3.1.2 Cathodic alkaline cleaning is preferred for the final
1.3 This international standard was developed in accor-
precleaning so as to avoid anodic oxidation. Proprietary
dance with internationally recognized principles on standard-
formulations used for cathodic alkaline cleaning of other
ization established in the Decision on Principles for the
metals are suitable. Cathodic treatment at about 6 V for 30 to
Development of International Standards, Guides and Recom-
60 s is usually adequate, using a cleaner concentration of 60 to
mendations issued by the World Trade Organization Technical
75g/L and a solution temperature of 60 to 75 °C.
Barriers to Trade (TBT) Committee.
3.2 Rinse—Here, and throughout the procedure, the water
rinses should be warm (approximately 50 °C).
2. Significance and Use
3.3 Electropolishing—Either of the following electropol-
2.1 Molybdenum is used in engineering applications where
ishes may be used. The choice of electropolish and time
strength and rigidity of component parts are needed, especially
depends on the amount of material that can be removed and the
at high temperatures. Its good strength at high temperatures,
degree of surface improvement desired. The cathodes may be
low vapor pressure, and good impact and creep resistance
lead or carbon. The sulfuric acid bath produces a blue film that
makeitattractiveforload-bearingitemssuchasturbineblades,
is partly removed in the rinse and completely removed in the
mechanical seals, rocket motor parts, heating elements, and
alkaline dip.
electronic devices. Molybdenum, however, is easily oxidized,
3.3.1 Sulfuric Acid:
and the oxides are not protective. The volatility of the oxides
above 800 °C can lead, in the case of unprotected parts, to H SO (sp gr 1.83) 80 mass % (755 mL of acid/L)
2 4
Temperature 20 to 30 °C
catastrophic oxidation and to losses in dimensions. Electro-
Current density 1100 to 2200 A/m anodic
plated coatings are applied to molybdenum to prevent
Time 30 s
oxidation, to prevent seizing and ga
...




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