GB/T 4955-2005Metallic coatings -- Measurement of coating thickness -- Coulometric method by anodic dissolution (English PDF)

Foreword

This Standard identically adopts ISO 2177.2003 "Metallic coatings - Measurement of

coating thickness - Coulometric method by anodic dissolution" (English version).

This Standard was redrafted based on ISO 2177.2003.This Standard has been modified

in accordance with ISO 2177 as follows.

- Delete the foreword of ISO 2177;

- For ease of use, it adopts Chinese standards that corresponds to the international

standards;

- Add the introduction to the normative references;

- Use "this Standard" to replace "this International Standard".

This Standard replaces GB/T 4955-1997 "Metallic coatings -- Measurement of coating

thickness -- Coulometric method by anodic dissolution".

Compared with GB/T 4955-1997, the main changes in this Standard are as follows.

- Modify the measurable combinations in Table 1.Add the thickness measurement

of the gold plating layer;

- Add the normative references;

- Modify Clause 8 Procedure. Add the requirements for note in 8.7;

- Modify Clause 9 Thickness calculation formula;

- Modify the appendix regarding typical electrolytes. Add electrolyte for gold;

- Modify the size requirements for electrolytic cells in the appendix. Add the

requirement for small size. Add requirements for hot-dip coating and multi

coating thickness measurement.

Annex A and Annex B of this Standard are informative.

This Standard was proposed by China Machinery Industry Federation.

This Standard shall be under the jurisdiction of National Technical Committee on

Metallic and non-metallic coatings of Standardization Administration of China.

The drafting organizations of this Standard. Wuhan Institute of Material Protection and

Guangzhou Entry-Exit Inspection and Quarantine Bureau Chemical Mineral Gold

Center.

Metallic coatings - Measurement of coating thickness -

Coulometric method by anodic dissolution

1 Scope

This document describes a coulometric method, by anodic dissolution, for measuring

the thickness of metallic coatings. It is only applicable to conductive coatings.

Typical combinations of coatings and substrates that can be tested by this method are

given in Table 1.Other combinations may be tested with electrolytes in current use (see

Annex A), or new electrolytes may be developed for them but, in both cases, it is

necessary to verify the suitability of the complete system.

This Standard is also applicable to multi-layer systems, e.g. Cu-Ni-Cr (see also 8.5).

It may be used to measure the thickness of coatings applied by various means, if due

account is taken of special features such as the presence of an alloy layer. In some cases,

the presence and thickness of diffusion layers can also be measured. It can also be used

to measure the thickness of coatings on cylindrical specimens and wires (see 8.7).

8 Procedure