5.1 The thickness of a coating is often critical to its performance. This magnetic method is suitable for measuring nondestructively the thickness of some nickel coatings and for specification acceptance.

5.2 This method requires that the magnetic properties of the coating and its substrate be the same as those of the reference standards used for the calibration adjustment of the instrument.

5.3 This method should not be used to determine the thickness of autocatalytically deposited nickel-phosphorus alloys containing more than 8 % phosphorus on steel. Those coatings are sufficiently nonmagnetic for Test Method B499 to be suitable for that determination, as long as the measurement is made prior to any heat treatment.

1.1 This test method covers the use of magnetic instruments for the nondestructive measurement of the thickness of an electrodeposited nickel coating on either a magnetic or nonmagnetic substrate. It is intended to supplement manufacturers’ instructions for the operation of the instruments and is not intended to replace them.

1.2 These instruments measure either the magnetic attraction between a magnet and the coating-substrate combination (categorized as “magnetic pull-off”), or the change in magnetic flux density within the probe (categorized as “electronic”).

1.3 For this test method, there are two types of coating-substrate combinations that can be encountered: Type A, nickel coatings on a magnetic substrate, and Type B, nickel coatings on a nonmagnetic substrate.

1.4 The effective measuring ranges of instruments using the principle of magnetic attraction are up to 50 μm (2 mils) for Type A coatings, and up to 25 μm (1 mil) for Type B coatings. For gages based on change in magnetic flux density principles, the effective ranges are much greater, and measurements up to 1 mm (40 mils) or more, can be made on both types of coatings.

1.5 Measurements made in accordance with this test method will be in compliance with the requirements of ISO Standard 2361 as printed in 1982.

1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.7 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.