ASTM B879-17
(Practice)Standard Practice for Applying Non-Electrolytic Conversion Coatings on Magnesium and Magnesium Alloys
Standard Practice for Applying Non-Electrolytic Conversion Coatings on Magnesium and Magnesium Alloys
SIGNIFICANCE AND USE
3.1 The processes described in this practice clean and provide a paint base for the finishing of magnesium and magnesium alloys. Service conditions will determine, to some degree, the specific process to be applied.
SCOPE
1.1 This practice covers a guide for metal finishers to clean and then provide a paint base for the finishing of magnesium and magnesium alloys using chemical conversion coatings. Where applicable (for example, aerospace) secondary supplementary coatings (for example, surface sealing) can be used (see Appendix X1).
1.2 Although primarily intended as a base for paint, chemical conversion coatings provide varying degrees of surface protection for magnesium parts exposed to indoor atmosphere either in storage or in service under mild exposure conditions. An example is the extensive use of the dichromate treatment (see 5.2) as a final coating for machined surfaces of die cast magnesium components in the computer industry.
1.3 The traditional numbering of the coating is used throughout.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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.
1.6 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.
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Designation: B879 − 17
Standard Practice for
Applying Non-Electrolytic Conversion Coatings on
1
Magnesium and Magnesium Alloys
This standard is issued under the fixed designation B879; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
2
1. Scope 2.2 ASTM Standards:
D1732Practices for Preparation of Magnesium Alloy Sur-
1.1 This practice covers a guide for metal finishers to clean
faces for Painting
and then provide a paint base for the finishing of magnesium
3
2.3 SAE Standard:
and magnesium alloys using chemical conversion coatings.
AMS 2475Protective Treatments—Magnesium Alloys
Where applicable (for example, aerospace) secondary supple-
4
2.4 Military Specifications:
mentary coatings (for example, surface sealing) can be used
MIL-M-3171Magnesium Alloy, Processes for Pretreatment
(see Appendix X1).
and Prevention of Corrosion on
1.2 Although primarily intended as a base for paint, chemi-
DTD 911(British), Protection of Magnesium-Rich Alloys
cal conversion coatings provide varying degrees of surface
Against Corrosion
protection for magnesium parts exposed to indoor atmosphere
DTD5562(British),ClearBakingResinforSurfaceSealing
either in storage or in service under mild exposure conditions.
Magnesium
An example is the extensive use of the dichromate treatment
DTD 935(British), Surface Sealing of Magnesium Rich
(see 5.2) as a final coating for machined surfaces of die cast
Alloys
magnesium components in the computer industry.
3. Significance and Use
1.3 The traditional numbering of the coating is used
throughout.
3.1 The processes described in this practice clean and
provide a paint base for the finishing of magnesium and
1.4 The values stated in SI units are to be regarded as
magnesium alloys. Service conditions will determine, to some
standard. No other units of measurement are included in this
degree, the specific process to be applied.
standard.
1.5 This standard does not purport to address all of the
4. Reagents
safety concerns, if any, associated with its use. It is the
4.1 Thechemicalsthatareusedtoformulateandcontrolthe
responsibility of the user of this standard to establish appro-
processing solutions are listed in Table 1. Commercial grade
priate safety, health, and environmental practices and deter-
chemicalsaresatisfactory.Theconcentrationsstatedforchemi-
mine the applicability of regulatory limitations prior to use.
cals that are normally supplied at less than a nominal 100%
1.6 This international standard was developed in accor-
strength are those typically available. Other strengths may be
dance with internationally recognized principles on standard-
used in the proportions that yield the specified processing
ization established in the Decision on Principles for the
concentrations. Unless otherwise stated all solutions are made
Development of International Standards, Guides and Recom-
up using water.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5. Types of Coating
5.1 Chrome Pickle (Traditional Number 1) Treatment (See
2. Referenced Documents
Practices D1732):
2.1 The following documents form a part of this practice to
the extent referenced herein.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
1
This practice is under the jurisdiction of ASTM Committee B08 on Metallic the ASTM website.
3
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 on Available from Society of Automotive Engineers (SAE), 400 Commonwealth
Conversion Coatings. Dr., Warrendale, PA 15096-0001, http://www.sae.org.
4
Current edition approved Nov. 1, 2017. Published November 2017. Originally Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
approvedin1997.Lastpreviouseditionapprovedin2013asB879–97(2013).DOI: Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
10.1520/B0879-17. dodssp.daps.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
B879 − 17
TABLE 1 Processing Chemicals
5.3 Galvanic Chromate (Traditional Number 9) Treatment
Acetic acid glacial, (CH COOH) (see Practices D1732):
3
3
Aluminum sulfate (Al [SO ] ·14H O)
2 3 2
5.3.1 This treatment can be used for all alloys and is
Ammonium bifluoride (NH HF )
4 2
specifically used for those alloys which do not react or form
Ammonium hydroxide (NH OH), 30 %
4
Ammoni
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B879 − 97 (Reapproved 2013) B879 − 17
Standard Practice for
Applying Non-Electrolytic Conversion Coatings on
1
Magnesium and Magnesium Alloys
This standard is issued under the fixed designation B879; 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
1.1 This practice covers a guide for metal finishers to clean and then provide a paint base for the finishing of magnesium and
magnesium alloys using chemical conversion coatings. Where applicable (for example, aerospace) secondary supplementary
coatings (for example, surface sealing) can be used (see Appendix X1).
1.2 Although primarily intended as a base for paint, chemical conversion coatings provide varying degrees of surface protection
for magnesium parts exposed to indoor atmosphere either in storage or in service under mild exposure conditions. An example is
the extensive use of the dichromate treatment (see 5.2) as a final coating for machined surfaces of die cast magnesium components
in the computer industry.
1.3 The traditional numbering of the coating is used throughout.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 The following documents form a part of this practice to the extent referenced herein.
2
2.2 ASTM Standards:
D1732 Practices for Preparation of Magnesium Alloy Surfaces for Painting
3
2.3 SAE Standard:
AMS 2475 Protective Treatments—Magnesium Alloys
4
2.4 Military Specifications:
MIL-M-3171 Magnesium Alloy, Processes for Pretreatment and Prevention of Corrosion on
DTD 911 (British), Protection of Magnesium-Rich Alloys Against Corrosion
DTD 5562 (British), Clear Baking Resin for Surface Sealing Magnesium
DTD 935 (British), Surface Sealing of Magnesium Rich Alloys
3. Significance and Use
3.1 The processes described in this practice clean and provide a paint base for the finishing of magnesium and magnesium
alloys. Service conditions will determine, to some degree, the specific process to be applied.
1
This practice is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 on
Conversion Coatings.
Current edition approved May 1, 2013Nov. 1, 2017. Published May 2013November 2017. Originally approved in 1997. Last previous edition approved in 20082013 as
ε1
B879 – 97(2008)97(2013). . DOI: 10.1520/B0879-97R13.10.1520/B0879-17.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, http://www.sae.org.
4
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://dodssp.daps.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
B879 − 17
4. Reagents
4.1 The chemicals that are used to formulate and control the processing solutions are listed in Table 1. Commercial grade
chemicals are satisfactory. The concentrations stated for chemicals that are normally supplied at less than a nominal 100 % strength
are those typically available. Other strengths may be used in the proportions that yield the specified processing concentrations.
Unless otherwise stated all solutions are made up using water.
5. Types of Coating
5.1 Chrome Pickle (Traditional Number 1) Tr
...
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