Metallic and other inorganic coatings — Cleaning and preparation of metal surfaces — Part 2: Non-ferrous metals and alloys

ISO 27831-2:2008 specifies processes for the cleaning of the surfaces of non-ferrous metals and their alloys to remove any irrelevant or unwanted deposits or other material at any stage of manufacture, storage or service and for the preparation of these surfaces for further treatment. It does not cover cleaning operations associated with the preliminary removal of heavy deposits of oil, grease or dirt accumulated during operational service, preparations for welding or the cleaning of electrical contacts. It covers processes which are needed for the preparation of metal surfaces prior to the application of the following surface coatings: electrodeposited metal coatings; autocatalytic metal coatings (autocatalytic and displacement types); conversion coatings; anodic oxidation coatings; hot-dipped coatings; sprayed metal coatings; coatings produced by vitreous enamelling; coatings produced by physical vapour deposition of aluminium and cadmium; powder coatings. It describes processes for carrying out the following treatments: degreasing; descaling; pickling; etching; de-rusting; chemical smoothing; chemical polishing; electrobrightening; electropolishing; fluoride anodizing (for cleaning magnesium alloys). It relates the processes described above to the following metals: aluminium and aluminium alloys; copper and copper alloys; nickel alloys; titanium and titanium alloys; magnesium alloys; zinc-based alloys; tin and tin alloys; tungsten alloys; lead and lead alloys; zinc-, cadmium-, chromium- and gold-coated items.

Revêtements métalliques et autres revêtements inorganiques — Nettoyage et préparation des surfaces métalliques — Partie 2: Métaux non ferreux et alliages

General Information

Status
Published
Publication Date
01-Oct-2008
Current Stage
9093 - International Standard confirmed
Start Date
20-Mar-2013
Completion Date
18-Dec-2018
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ISO 27831-2:2008 - Metallic and other inorganic coatings -- Cleaning and preparation of metal surfaces
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INTERNATIONAL ISO
STANDARD 27831-2
First edition
2008-10-15
Metallic and other inorganic coatings —
Cleaning and preparation of metal
surfaces —
Part 2:
Non-ferrous metals and alloys
Revêtements métalliques et autres revêtements inorganiques —
Nettoyage et préparation des surfaces métalliques —
Partie 2: Métaux non ferreux et alliages
Reference number
ISO 27831-2:2008(E)
ISO 2008
---------------------- Page: 1 ----------------------
ISO 27831-2:2008(E)
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ii © ISO 2008 – All rights reserved
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ISO 27831-2:2008(E)
Contents Page

Foreword........................................................................................................................................................... vii

Introduction ..................................................................................................................................................... viii

1 Scope ..................................................................................................................................................... 1

2 Normative references ........................................................................................................................... 2

3 Terms and definitions........................................................................................................................... 3

4 Essential information to be supplied by the purchaser to the processor ...................................... 3

5 Requirements ........................................................................................................................................ 4

6 Standard cleaning methods................................................................................................................. 5

7 Non-corrosion-resisting steels, cast irons and pure irons .............................................................. 5

8 Corrosion-resisting and heat-resisting steels ...................................................................................6

9 Pretreatment of metals prior to powder coating ............................................................................... 6

10 Cleaning and preparation processes.................................................................................................. 6

11 Aluminium and aluminium alloys........................................................................................................ 6

11.1 General................................................................................................................................................... 6

11.2 General degreasing and cleaning ....................................................................................................... 6

11.3 Removal of corrosion products .......................................................................................................... 6

11.4 Preparation prior to anodizing ............................................................................................................ 7

11.5 Preparation prior to oxide removal treatment (process O) or filming treatment ........................... 7

11.6 Preparation prior to adhesive bonding of unanodized items .......................................................... 7

11.7 Preparation prior to electroplating...................................................................................................... 7

11.8 Preparation prior to autocatalytic nickel plating ...............................................................................7

11.9 Preparation prior to conversion coating ............................................................................................ 7

11.10 Preparation prior to metal spraying.................................................................................................... 7

11.11 Preparation prior to vitreous enamelling ........................................................................................... 8

11.11.1 Sheet, extrusions and items made from casting alloys.................................................................... 8

11.11.2 Other castings....................................................................................................................................... 8

11.12 Preparation prior to supplementary treatments on physically vapour deposited aluminium...... 8

12 Copper and copper alloys.................................................................................................................... 8

12.1 General degreasing and cleaning ....................................................................................................... 8

12.2 Preparation prior to electroplating...................................................................................................... 9

12.3 Preparation prior to autocatalytic nickel plating ...............................................................................9

12.4 Preparation prior to hot tinning (TRI process) ................................................................................ 10

12.5 Preparation prior to vitreous tinning ................................................................................................ 10

13 Nickel alloys ........................................................................................................................................ 10

13.1 General degreasing and cleaning ..................................................................................................... 10

13.2 Preparation prior to electroplating.................................................................................................... 10

13.3 Preparation prior to autocatalytic deposition.................................................................................. 11

13.4 Preparation prior to vitreous enamelling ......................................................................................... 11

14 Titanium and titanium alloys ............................................................................................................. 11

14.1 General degreasing and cleaning ..................................................................................................... 11

14.2 Preparation prior to electroplating.................................................................................................... 12

14.3 Preparation prior to autocatalytic nickel plating ............................................................................. 12

15 Magnesium alloys............................................................................................................................... 12

15.1 General degreasing and cleaning prior to electroplating and conversion coating ..................... 12

© ISO 2008 – All rights reserved iii
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ISO 27831-2:2008(E)

15.2 Preparation prior to electroplating.................................................................................................... 12

15.3 Preparation prior to conversion coating .......................................................................................... 13

15.3.1 General ................................................................................................................................................. 13

15.3.2 As-cast castings.................................................................................................................................. 13

15.3.3 Machined castings .............................................................................................................................. 14

15.3.4 Forgings............................................................................................................................................... 14

15.3.5 Sheets and extrusions........................................................................................................................ 14

16 Zinc-based alloys ................................................................................................................................ 14

16.1 General degreasing and cleaning ..................................................................................................... 14

16.2 Cleaning of corroded items................................................................................................................ 14

16.3 Preparation of zinc alloy die castings prior to electroplating ........................................................ 14

16.4 Preparation of zinc alloy castings prior to chromate conversion coating or phosphate

treatment.............................................................................................................................................. 14

17 Tin and its alloys ................................................................................................................................. 14

18 Tungsten alloys................................................................................................................................... 15

18.1 Preparation prior to electroplating.................................................................................................... 15

18.2 Preparation prior to adhesive bonding............................................................................................. 15

19 Lead and its alloys .............................................................................................................................. 15

20 Zinc-, cadmium-, chromium- and gold-coated items....................................................................... 15

20.1 Preparation of zinc-coated items prior to chromate conversion coating ..................................... 15

20.2 Preparation of cadmium-coated items prior to chromate conversion coating ............................ 15

20.3 Preparation of physically vapour deposited cadmium prior to supplementary treatments ....... 15

20.4 Preparation for chromium-coated parts prior to supplementary treatments ............................... 16

20.5 Removal of surface contamination from gold coatings.................................................................. 16

21 Pretreatment of metals prior to powder coating.............................................................................. 16

21.1 Preparation of aluminium prior to powder coating ......................................................................... 16

21.2 Preparation of zinc and hot-dip-galvanized steel prior to powder coating................................... 16

21.3 Preparation of copper and brass prior to powder coating ............................................................. 16

22 Cleaning and preparation processes................................................................................................ 16

22.1 Process A — Organic-solvent degreasing and cleaning ................................................................ 17

22.1.1 General ................................................................................................................................................. 17

22.1.2 Method A1 — Hot solvent, not water-rinsable ................................................................................. 17

22.1.3 Method A2 — Cold solvent, not water-rinsable ............................................................................... 17

22.1.4 Method A3 — Hot solvent, water-rinsable ........................................................................................ 17

22.1.5 Method A4 — Cold solvent, water-rinsable ...................................................................................... 18

22.1.6 Method A5 — Petroleum fuel based mixtures containing emulsifying agents ............................ 18

22.1.7 Method A6 — Ultrasonic cleaning..................................................................................................... 18

22.2 Process B — Alkaline degreasing..................................................................................................... 18

22.2.1 General ................................................................................................................................................. 18

22.2.2 Method B1 — General-purpose alkaline degreasing....................................................................... 18

22.2.3 Method B2 — Mild alkaline degreasing ............................................................................................18

22.2.4 Method B3 — Cathodic alkaline degreasing .................................................................................... 19

22.3 Process C — Acid emulsion cleaning............................................................................................... 19

22.4 Process D — Abrasive cleaning ........................................................................................................ 19

22.4.1 General ................................................................................................................................................. 19

22.4.2 Method D1 — Coarse-abrasive blasting ........................................................................................... 19

22.4.3 Method D2 — Fine-abrasive blasting ................................................................................................ 19

22.4.4 Method D3 — Scouring....................................................................................................................... 19

22.4.5 Method D4 — Tumbling...................................................................................................................... 20

22.4.6 Method D5 — Wire brushing.............................................................................................................. 20

22.5 Process E — Caustic-alkali descaling .............................................................................................. 20

22.6 Process F — Acid pickling without electrolysis .............................................................................. 20

22.7 Process G — Acid dipping................................................................................................................. 20

22.8 Process H — Anodic pickling ............................................................................................................ 20

22.8.1 General ................................................................................................................................................. 20

22.8.2 Method H1............................................................................................................................................ 20

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ISO 27831-2:2008(E)

22.9 Process J — Acid de-rusting............................................................................................................. 20

22.10 Process K — Alkaline de-rusting ...................................................................................................... 21

22.11 Process L — Chemical smoothing and electropolishing of steels ............................................... 21

22.12 Process M — Passivation and removal of surface contamination from corrosion-resisting

steels and surface preparation prior to electroplating ................................................................... 21

22.13 Process N — Acid pickling of aluminium alloys ............................................................................. 21

22.13.1 General................................................................................................................................................. 21

22.13.2 Method N1............................................................................................................................................ 21

22.13.3 Method N2............................................................................................................................................ 21

22.13.4 Method N3............................................................................................................................................ 21

22.13.5 Method N4............................................................................................................................................ 22

22.13.6 Method N5............................................................................................................................................ 22

22.13.7 Method N6............................................................................................................................................ 22

22.14 Process O — Oxide removal, i.e. “etching”, treatment of aluminium and aluminium alloys ..... 22

22.14.1 General................................................................................................................................................. 22

22.14.2 Degreasing and cleaning ................................................................................................................... 22

22.14.3 Preparation prior to anodizing and adhesive bonding ................................................................... 23

22.15 Process P — Aluminium and aluminium alloys — Removal of corrosion products, etching

treatment, chemical polishing, electrobrightening and electropolishing..................................... 24

22.15.1 Removal of corrosion products ........................................................................................................ 24

22.15.1.1 Method P1 — Immersion ............................................................................................................ 24

22.15.1.2 Method P2 — Swabbing ............................................................................................................. 24

22.15.2 Etching treatment ............................................................................................................................... 24

22.15.2.1 Method P3 — Etching by brushing or spray treatment........................................................... 24

22.15.2.2 Method P4 — Etching and de-smutting treatment using sodium hydroxide........................ 24

22.15.3 Method P5 — Chemical polishing..................................................................................................... 25

22.15.4 Method P6 — Electrobrightening...................................................................................................... 25

22.15.5 Method P7 — Electropolishing.......................................................................................................... 26

22.16 Process Q — Cleaning of copper and copper alloys...................................................................... 26

22.16.1 Method Q1 — Cleaning in dichromate/sulfuric acid solution ........................................................ 26

22.16.2 Method Q2 — Cleaning in ferric sulfate/sulfuric acid solution ...................................................... 26

22.17 Process R — Acid descaling, etching, chemical smoothing and electropolishing of

copper and copper alloys .................................................................................................................. 26

22.17.1 Method R1 — Descaling dip .............................................................................................................. 26

22.17.2 Method R2 — Bright dip..................................................................................................................... 26

22.17.3 Method R3 — Chemical smoothing ..................................................................................................27

22.17.4 Method R4 — Pickling in nitric acid.................................................................................................. 27

22.17.5 Method R5 — Electropolishing.......................................................................................................... 27

22.18 Process S — Pickling of titanium and titanium alloys.................................................................... 27

22.18.1 General................................................................................................................................................. 27

22.18.2 Method S1............................................................................................................................................ 27

22.18.3 Method S2............................................................................................................................................ 27

22.19 Process T — Pickling, chemical polishing and electropolishing of nickel and its alloys........... 28

22.19.1 General................................................................................................................................................. 28

22.19.2 Method T1 ............................................................................................................................................ 28

22.19.3 Method T2 ............................................................................................................................................ 28

22.19.4 Method T3 ............................................................................................................................................ 28

22.19.5 Method T4 — Chemical polishing ..................................................................................................... 28

22.19.6 Method T5 — Electropolishing .......................................................................................................... 29

22.20 Process U — Preparation of tin alloy for electroplating................................................................. 29

22.21 Process V — Removal of surface contamination from gold coatings .......................................... 29

22.22 Process W — Preparation of aluminium alloys prior to electroplating......................................... 29

22.23 Process X — Preparation of nickel alloys prior to electroplating ................................................. 30

22.24 Process Y — Preparation of titanium alloys prior to electroplating.............................................. 31

22.24.1 Method Y1 — General method for titanium alloys .......................................................................... 31

22.24.2 Method Y2 — Method for titanium and selected titanium alloys ................................................... 32

22.24.3 Method Y3 — Chemical-etching method.......................................................................................... 32

22.25 Process Z — Preparation of zinc and zinc alloys prior to electroplating ..................................... 33

22.25.1 Method Z1 ............................................................................................................................................ 33

22.25.2 Method Z2 ............................................................................................................................................ 33

© ISO 2008 – All rights reserved v
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ISO 27831-2:2008(E)

Annex A (informative) Maintenance of organic and vapour degreasing baths.......................................... 34

Annex B (informative) The control of acidity in vapour cleaning baths ..................................................... 35

Annex C (normative) Method for the determination of oxidizable material in sulfuric acid..................... 36

Annex D (informative) Method for determining free acidity ......................................................................... 37

Annex E (normative) Selection of method of cleaning according to the tensile strength of the

steel in zinc-coated steel items prior to chromate conversion coating ........................................ 38

Annex F (normative) Method M4.....................................................................................................................40

Bibliography ..................................................................................................................................................... 41

vi © ISO 2008 – All rights reserved
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ISO 27831-2:2008(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 27831-2 was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,

Subcommittee SC 3, Electrodeposited coatings and related finishes.

ISO 27831 consists of the following parts, under the general title Metallic and other inorganic coatings —

Cleaning and preparation of metal surfaces:
⎯ Part 1: Ferrous metals and alloys
⎯ Part 2: Non-ferrous metals and alloys
© ISO 2008 – All rights reserved vii
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ISO 27831-2:2008(E)
Introduction

The adhesion of deposited coatings depends upon the efficiency of degreasing and cleaning processes used

on the substrate surface. The removal of grease, oil and dirt and all other forms of contamination left from

fabrication processes or due to corrosion/erosion of surfaces in storage or in service is essential for successful

production of a pristine, chemically clean active surface for deposition of coatings.

The surface contaminants can be

⎯ corrosion products, mould sand or mould release agents on ferrous and non-ferrous castings;

⎯ corrosion products and mill scales on hot-rolled steel sheet, girders, etc. (broken mill scale is cathodic to

the underlying substrate);
⎯ oil and rolling lubricant on cold-rolled steel sheet;
⎯ rolling lubricant on e.g. cold-rolled aluminium sheet;

⎯ corrosion products on delivery or during storage on hot-dip-galvanized steel sheet or angle bars/brackets;

⎯ other undesirable materials from storage and handling.
The difficulty of coating these surfaces is well known.

Cleaning processes for removing surface contaminants are varied, depending, among other things, on the

identification and classification of the soil as well as the size and shape of the substrate, the degree of

cleanliness required, the availability of the facilities needed, the cost of the processes used and their impact

on the environment, and the nature of subsequent processes to which the substrate is going to be subjected.

ISO 27831 includes cleaning processes ranging from mechanical methods (which give the least degree of

cleanliness) to chemical and ultrasonic methods (which give a higher degree of surface preparation) and

substrate conditioning by glow discharge plasma (sputter cleaning) for vapour deposition.

ISO 27831 describes practices for cleaning a variety of metals and metal alloys prior to the application of a

range of coatings or without any coating requirements.

The cleaning processes described in ISO 27831-1 and ISO 27831-2 are indicative only of those most

commonly used in practice. However, there are numerous formulations of solutions and numerou

...

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