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ASTM D 2674 : 1972 : R2012

Superseded
Superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

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superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

Standard Methods of Analysis of Sulfochromate Etch Solution Used in Surface Preparation of Aluminum
Available format(s)

Hardcopy , PDF

Superseded date

07-02-2021

Language(s)

English

Published date

05-14-2012

CONTAINED IN VOL. 15.06, 2015 Defines a means for controlling the effectiveness of the etchant which is normally used for preparing the surface of aluminum alloys for subsequent adhesive bonding.

1.1 These methods offer a means for controlling the effectiveness of the etchant which is normally used for preparing the surface of aluminum alloys for subsequent adhesive bonding. As the etchant reacts with the aluminum, hexavalent chromium is converted to trivalent chromium; a measure of the two and the difference can be used to determine the amount of dichromate used.

1.2 The sulfochromate solution can be replenished by restoring the sodium dichromate and the sulfuric acid to the original formulation levels. The lower limit of usefulness will vary depending upon solution storage, adhesives used, critical nature of bond capability, variety of metals processed, etc. and should be determined. Replenishment will be limited to the number of times the chemical ingredients can be restored and maintained to the required levels and should be determined by the user. Sludge collecting in the bottom of a tank should be minimized by periodic removal of sludge. For some applications, the hexavalent chromium should not fall below the trivalent chromium content.

1.3 A typical aqueous sulfochromate acid etch solution formulation is as follows:

Sodium dichromate (Na2Cr2O7)4.5 oz/gal (33.7 g/litre)
Sulfuric acid (sp gr 1.84)45 oz/gal (337.1 g/litre)

1.4 Maintenance of the aqueous concentrations is suggested as follows by appropriate additions of sodium dichromate or sulfuric acids.

Sodium dichromate3.0 to 6.0 oz/gal (22.5 to 44.9 g/litre)
Sulfuric acid40 to 50 oz/gal (299.6 to 374.5 g/litre)

1.5 Method A is intended for measuring the sulfuric acid content of a sulfochromate solution. Method B is intended for measuring the hexavalent and trivalent Chromium content of a sulfochromate solution. Method C is intended as an alternative method for measuring the hexavalent and trivalent Chromium content of a sulfochromate solution.

1.6 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 and health practices and determine the applicability of regulatory limitations prior to use.

Committee
D 14
DocumentType
Standard
Pages
3
ProductNote
Reconfirmed 2012
PublisherName
American Society for Testing and Materials
Status
Superseded
SupersededBy
Supersedes

ASTM E 864 : 2020 Standard Practice for Surface Preparation of Aluminum Alloys to Be Adhesively Bonded in Honeycomb Shelter Panels
ASTM D 2651 : 2001 : R2016 Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding
ASTM E 864 : 2012 Standard Practice for Surface Preparation of Aluminum Alloys to Be Adhesively Bonded in Honeycomb Shelter Panels
ASTM D 6465 : 1999 : R2016 Standard Guide for Selecting Aerospace and General Purpose Adhesives and Sealants

ASTM D 1193 : 1977 : R1983 : EDT 1 Standard Specification for Reagent Water
ASTM E 50 : 2017 : REDLINE Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
ASTM D 1193 : 2006 : R2011 Standard Specification for Reagent Water
ASTM D 1193 : 1991 Standard Specification for Reagent Water
ASTM D 1193 : 1970 Standard Specification For Reagent Water
ASTM D 1193 : 2006 Standard Specification for Reagent Water
ASTM E 50 : 1982 : R1986 Standard Practices for Apparatus, Reagents, and Safety Precautions for Chemical Analysis of Metals
ASTM D 1193 : 1999 Standard Specification for Reagent Water
ASTM D 1193 : 2006 : R2018 Standard Specification for Reagent Water

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