This standard specifies the method of using coating thickness instruments of the magnetic type for non-destructive measurements of the thickness of non-magnetic coatings (including vitreous and porcelain enamel coatings) on magnetic basis metals.
The method is applicable only for measurements on reasonably flat specimens. In the case of nickel coatings on non-magnetic substrates, the preferred method is that specified in GB/T 13744.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.
GB/T 12334 Metallic and other inorganic coatings—Definitions and conventions concerning the measurement of thickness (idt ISO 2064)
GB/T 13744 The measurement of coating thickness for electrodeposited nickel coatings on magnetic and non-magnetic substrates (eqv ISO 2361)
3 Principle
Coating thickness instruments of the magnetic type measure either the magnetic attraction between a permanent magnet and the basis metal, as influenced by the presence of the coating, or the reluctance of a magnetic flux path passing through the coating and the basis metal.
Foreword i 1 Scope 2 Normative references 3 Principle 4 Factors affecting the measuring accuracy1) 5 Calibration of instruments 6 Procedure 7 Accuracy requirement
1 Scope
This standard specifies the method of using coating thickness instruments of the magnetic type for non-destructive measurements of the thickness of non-magnetic coatings (including vitreous and porcelain enamel coatings) on magnetic basis metals.
The method is applicable only for measurements on reasonably flat specimens. In the case of nickel coatings on non-magnetic substrates, the preferred method is that specified in GB/T 13744.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition applies.
GB/T 12334 Metallic and other inorganic coatings—Definitions and conventions concerning the measurement of thickness (idt ISO 2064)
GB/T 13744 The measurement of coating thickness for electrodeposited nickel coatings on magnetic and non-magnetic substrates (eqv ISO 2361)
3 Principle
Coating thickness instruments of the magnetic type measure either the magnetic attraction between a permanent magnet and the basis metal, as influenced by the presence of the coating, or the reluctance of a magnetic flux path passing through the coating and the basis metal.
Contents of GB/T 4956-2003
Foreword i
1 Scope
2 Normative references
3 Principle
4 Factors affecting the measuring accuracy1)
5 Calibration of instruments
6 Procedure
7 Accuracy requirement
