ASTM E866-23

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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: E866 − 19 E866 − 23
Standard Specification for
Corrosion-Inhibiting Adhesive Primer for Aluminum Alloys
to Be Adhesively Bonded in Honeycomb Shelter Panels
This standard is issued under the fixed designation E866; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This specification covers sprayable, pigmented liquid primers for use on aluminum alloys that are to be adhesively bonded in
the fabrication of honeycomb sandwich panels for tactical shelters. When applied to a properly cleaned surface of aluminum alloy,
the primer imparts corrosion resistance and forms a surface suitable for structural bonding using adhesives complying with
Specification E865 and for coating with shelter paint finishes.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 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.
1.4 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 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
B209 Specification for Aluminum and Aluminum-Alloy Sheet and Plate (Metric) B0209_B0209M
D522/D522M Test Methods for Mandrel Bend Test of Attached Organic Coatings
D1002 Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading
(Metal-to-Metal)
D3167 Test Method for Floating Roller Peel Resistance of Adhesives
E631 Terminology of Building Constructions
E864 Practice for Surface Preparation of Aluminum Alloys to Be Adhesively Bonded in Honeycomb Shelter Panels
E865 Specification for Structural Film Adhesives for Honeycomb Sandwich Panels
E1749 Terminology Relating to Rigid Wall Relocatable Shelters
This specification is under the jurisdiction of ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.53 on Materials
and Processes for Durable Rigidwall Relocatable Structures.
Current edition approved July 1, 2019May 1, 2023. Published August 2019June 2023. Originally approved in 1982. Last previous edition approved in 20112019 as
E866E866 – 19.–11. DOI: 10.1520/E0866–19.10.1520/E0866-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2.2 Federal Specifications:
QQ-A-250/8d Aluminum Alloy 5052H34, Plate and Sheet
QQ-A-250/11d Aluminum Alloy 6061T6, Plate and Sheet
3. Terminology
3.1 Definitions—For definitions of general terms related to building construction used in this specification, refer to Terminology
E631, and for general terms related to rigid wall relocatable shelters, refer to Terminology E1749.
4. Materials and Manufacture
4.1 The primer shall be a pigmented liquid composed of a modified epoxy resin system, compounded so that it can be
spray-applied to produce a continuous uniform coating without addition of solvent.
5. Physical Requirements
5.1 The uncured primer must meet the requirements of Table 1. The cured primer must meet the requirements of Table 2 and Table
3. These requirements shall be verified by tests described in Section 6.
5.2 Properties of Cured Film—When applied and cured in accordance with 6.1.7, the cured film shall meet the requirements of
Table 2 and Table 3 when tested as specified in 6.2 – 6.3.8.
5.3 Storage Stability—Primer stored in accordance with the manufacturer’s instructions shall meet the requirements of Table 1 and
when cured in accordance with 6.1.7 shall meet the requirements of Table 2 and Table 3 when tested as specified in 6.2 – 6.3.8.
5.4 Shelf Life—The shelf life of the primer at 2525 °C 6 7 °C (77(77 °F 6 12 °F) shall be at least four days. After four days, when
tested in accordance with 6.1.4, the primer shall be capable of meeting all of the requirements of this specification.
5.5 Film Thickness—The film thickness for all tests shall be between 0.0030.003 mm and 0.007 mm (0.0001(0.0001 in. and 0.0003
in.).
6. Test Methods
6.1 Uncured Primer:
6.1.1 Solids Content—Determine the solids content by heating a 5 g sample of thoroughly mixed primer in an aluminum weighing
dish in a circulating air oven at 105105 °C 6 2 °C (221(221 °F 6 3 °F) for not less than 3 h. Calculate the mass of solids remaining
as a percentage of the initial sample mass. Weighings before and after heating shall be accurate to 60.001 g.60.001 g.
6.1.2 Inhibitor Content—Determine the inhibitor content in accordance with the following procedure (burn out method):
6.1.2.1 Tare four ignition loss crucibles and covers.
6.1.2.2 Pipette 2 mL portions of primer (1.75 g) from a well mixed sample into each crucible, add about 2 mL of MEK to each,
replace the lids, and devolatize the primer at 121121 °C 6 3 °C (250(250 °F 6 5 °F) for 6060 min 6 5 min.
TABLE 1 Physical Properties of Uncured Liquid Primer
Test Requirement
Solids content, % 10 ± 1
A
Inhibitor Content, % 15 ± 3
Color easily visible film
Sprayability film is of uniform thickness and color
A
Based on mass of nonvolatile content.
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TABLE 2 Physical Properties of Cured Film on Primed Surfaces
Test Requirement
Adhesion to metal no cracking or loss of adhesion
Impact resistance no cracking or loss of adhesion (on either side)
Pencil hardness 4H minimum
Water resistance no blistering, cracking, softening, or loss of
adhesion
Corrosion resistance no blistering, cracking, or substrate degradation
more than 3 mm from scribe mark
Humidity resistance no blistering, cracking, or loss of adhesion
Heat resistance no blistering, cracking, softening, or loss of
adhesion
Low-temperature shock no cracking or loss of adhesion
TABLE 3 Physical Properties of Bonded Specimens
Requirements
Test
(min)
Normal-temperature lap shear, 25 °C (77 °F), MPa (psi) 20.0 (2900)
Low-temperature lap shear, −55 °C (−67 °F), MPa (psi) 20.0 (2900)
High-temperature lap shear, 93 °C (200 °F), MPa (psi) 13.0 (1890)
Humidity-exposure lap shear, 93 °C (200 °F), MPa (psi) 5.0 (725)
Salt-spray exposure lap shear, 35 °C (95 °F), MPa (psi) 16.0 (2320)
Normal-temperature floating roller peel strength, 25 °C 4400 (25.1)
(77 °F), N ⁄m (lbf/in.)
Low-temperature floating roller peel strength, −55 °C 2625 (15.0)
(−67 °F), N ⁄m (lbf/in.)
6.1.2.3 Cool to room temperature in a desiccator, weigh, and compute the mass of the nonvolatiles. The nonvolatile content
requirement is 0.1550.155 g to 0.195 g/2 mL (10(10 % 6 1 % by weight).
6.1.2.4 Place the crucibles with lids (and residue) in a furnace at 593 °C (1100 °F) for 6060 min 6 5 min.
6.1.2.5 Cool to room temperature in a desiccator, weigh, and compute average mass of the inhibitor. The inhibitor content
requirement is 0.025 6 0.0030.025 g 6 0.003 g g/2 mL (15⁄2 mL (15 % 6 3 % by mass of nonvolatile content).
6.1.3 Storage Stability—Store a sample of the primer for six months from the date of shipment at −18 °C (0 °F), or two months
at 5 °C (41°F).(41 °F). Test the sample for ability to meet the requirements of Tables 1-3.
6.1.4 Shelf Life—Store a sample of the primer for four days at 2525 °C 6 7 °C (77(77 °F 6 12 °F) and then test for ability to meet
the requirements listed in Tables 1-3.
6.1.5 Color—Spray the primer onto an aluminum alloy panel, leaving a portion of the panel bare. Compare the coated and
uncoated areas visually against the color requirements in Table 1.
6.1.6 Sprayability—The primer shall be capable of being readily applied in accordance with the manufacturer’s instructions to all
test panels of either 6061T6 or 5052H34 aluminum alloy (Fed. Spec. QQ-A-250/8d or QQ-A-250/11d, respectively, or
Specification B209) and cleaned in accordance with Practice E864 for each of the tests described in 6.1.7 – 6.3.8. Inspect the
coating for uniformity of thickness and color.
6.1.7 Curing Properties—Spray the primer onto a test panel 100 by 150100 mm by 150 mm by 0.05 mm (4 by 6(4 in. by 6 in. by
0.020 in.) and air dry for at least 30 min at 2525 °C 6 5 °C (77(77 °F 6 9 °F); then heat in air for 7575 min to 90 min at 115115 °C
6 5 °C (239(239 °F 6 9 °F). Test the cured film for ability to meet the requirements listed in Table 2.
6.2 Cured Film:
6.2.1 Adhesion to Metal—Test the adhesion of the primer to the metal by bending a primed metal sample over a conical mandrel
in accordance with Test Methods D522/D522M, except use an aluminum alloy panel.
6.2.2 Impact Resistance—Determine the impact resistance of both the coated and uncoated side of a panel by subjecting the panel
to the impact of a 0.45 kg (1 lb) mass dropped from a height of 1 m 1 m (40 in.) using a Gardner 160 in.·lbf capacity impact testing
E866 − 23
machine or equivalent. Use the 0.45 kg (1 lb) falling weight. Apply a strip of masking tape over the most highly stressed area
on the coated side of each impact spot. Remove the tape in one abrupt motion by pulling perpendicular to the panel.
6.2.3 Pencil Hardness—Determine the pencil hardness of the cured film using the following procedure:
6.2.3.1 Preparation of Pencils—Prepare a set of drawing pencils ranging in hardness from 6B to 5H by stripping the wood away
from the end approximately 10 mm ( ⁄8 in.) without damaging the lead. Square the tip of the lead by holding the pencil in a vertical
position and moving the lead back and forth over 400 grit or finer abrasive paper. Square the tip of the lead after each trial.
6.2.3.2 Procedure—Place the test panel with the cured primer applied in a horizontal position. Push pencils of increasing hardness
into the coated surface of the panel at a 45° angle until one is found that will cut or scratch the coating. Use the number of this
pencil to express the primer hardness.
6.2.4 Environmental Resistance Test—For each test described in 6.2.5 – 6.2.9, clean five test panels of approximately 7575 mm
by 125 mm (3(3 in. by 5 in.) of either 6061T6 or 5052H34 aluminum alloy (Fed. Spec. QQ-A-250/8d or QQ-A-250/11d,
respectively, or Specification B209) in accordance with Practice E864. Apply the primer and cure in accordance with 6.1.7. These
panels when tested in accordance with the procedures described in 6.2.5 – 6.2.9 shall meet the requirements of Table 2.
6.2.5 Water Resistance—Immerse the panels with the cured primer applied in distilled water for seven days at 2424 °C 6 3 °C
(75(75 °F 6 5 °F) and then expose to 100 % relative humidity at 5050 °C 6 3 °C (121(121 °F 6 5 °F) for 30 days. After this
exposure, inspect the film for blistering and cracking and test for loss of adhesion as described in 6.2.10 and for pencil hardness
as in 6.2.3.
6.2.6 Heat Resistance—Heat the five test panels prepared as described in 6.2.4 at 120120 °C 6 3 °C (249(248 °F 6 5 °F) for 70
h. After this exposure, inspect the film for blistering and cracking and test for loss of adhesion as described in 6.2.10 and for pencil
hardness as in 6.2.3.
6.2.7 Low-Temperature Shock—Subject the five test panels prepared as in 6.2.4 to 24 cycles, each consisting of 25 min at 6565 °C
6 3 °C (150(150 °F 6 5 °F) then, following transfer within 5 s, 5 min at −55at −55 °C 6 3 °C (−66(−66 °F 6 5 °F). On
completion of the last cycle the panel shall remain in a cold box maintained at −55at −55 °C 6 3 °C (−66(−66 °F 6 5 °F) for 5
h. Bend the panel rapidly over a 100 mm (4 in.) diam
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