GB/T 4957-2003Non-conductive coatings on non-magnetic basis metals -- Measurement of coating thickness -- Eddy current (English PDF)

Foreword

This Standard identically adopts ISO 2360:1982 "Non-conductive coating on

non-magnetic basis metals - Measurement of coating thickness - Eddy current

method" (English edition).

This Standard replaces GB/T 4957-1985 "Non-conductive coatings on non-

magnetic metal substrates - Measurement of coating thickness - Eddy current

method".

Based on ISO 2360:1982, this Standard made the following editorial

modifications:

a) used "this Standard" to replace "this International standard";

b) deleted the foreword of ISO 2360:1982;

c) used national standards that adopt international standards as references;

d) added normative references.

This Standard was proposed by China Machinery Industry Federation.

This Standard shall be under the jurisdiction of National Technical Committee

on Metal and Non-metal Coatings of Standardization Administration of China.

Main drafting organization of this Standard: Wuhan Institute of Material

Protection.

The drafting organization of this Standard: Zhejiang Yueqing Xinfeng Enterprise

Co., Ltd.

Main drafters of this Standard: Yu Hui, Zhong Lichang, Feng Yongchun, Jia

Jianxin, Zheng Xiulin.

Version of standard substituted by this Standard is:

- GB/T 4957-1985.

Non-conductive coatings on non-magnetic basis

metals - Measurement of coating thickness - Eddy

current

1 Scope

This Standard describes a method for non-destructive measurements of the

thickness of nonconductive coatings on non-magnetic, electrically conductive

(generally metallic) basis materials, using amplitude-sensitive eddy current

instruments.

The method is particularly applicable to measurements of the thickness of most

oxide coatings produced by anodizing, but is not applicable to all conversion

coatings, some of which are too thin to be measured by this method (see Clause

7).

Although theoretically, the method can be used for measurements of the

thickness of coatings on magnetic basis materials, its use for this application is

not recommended. In such cases, the magnetic method specified in GB/T 4956

should be used.

2 Normative references

The provisions in following documents become the provisions of this Standard

through reference in this Standard. For dated references, the subsequent

amendments (excluding corrigendum) or revisions do not apply to this Standard,

however, parties who reach an agreement based on this Standard are

encouraged to study if the latest versions of these documents are applicable.

For undated references, the latest edition of the referenced document applies.

GB/T 4956, Non-magnetic coatings on magnetic substrates - Measurement

of coating thickness - Magnetic method (ISO2178:1982, IDT)

3 Principle

An eddy current probe (or integrated probe/instrument) is placed on the surface

of the coating(s) to be measured, and the thickness is read from the

instrument's readout.

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