This standard specifies the method for non-destructive measurement of the thickness of nickel electroplated layers on magnetic and non-magnetic substrates using a magnetic thickness gauge. This standard is applicable to the inspection of the thickness of nickel electroplated layers on magnetic and non-magnetic substrates. This standard does not apply to autocatalytic (non-electroplated) nickel coatings. GB/T 13744-1992 Measurement of the thickness of nickel electroplated layers on magnetic and non-magnetic substrates GB/T13744-1992 Standard download decompression password: www.bzxz.net
This standard specifies the method for non-destructive measurement of the thickness of nickel electroplated layers on magnetic and non-magnetic substrates using a magnetic thickness gauge. This standard is applicable to the inspection of the thickness of nickel electroplated layers on magnetic and non-magnetic substrates. This standard does not apply to autocatalytic (non-electroplated) nickel coatings.

National Standard of the People's Republic of China
Measurement of coating thickness for electrodeposited nickel coatings on magnetic and non-mugnetic substracts GE/T 13744-92
ISO 2361-1982
This standard is equivalent to the International Organization for Standardization IS02361-1982 "Measurement of thickness of nickel coatings on magnetic and non-magnetic substrates - Magnetic method".
1 Subject content and applicable scope
This standard specifies the method for non-destructive measurement of the thickness of nickel electroplated coatings on magnetic and non-magnetic substrates using a magnetic thickness gauge. This standard is applicable to the inspection of the thickness of nickel electroplated coatings on magnetic and non-magnetic substrates. This standard is not applicable to autocatalytic (non-electroplated) nickel coatings. 2 Reference standards
GB4955 Metal coating thickness measurement Anodic dissolution Coulomb method GB6462 Metal and oxide coating cross-sectional thickness microscope base measurement method 3 Terms and definitions
% Class A bond layer: nickel plating on magnetic substrate
b. Class B plating: nickel plating on non-magnetic substrate. 4 Principle
The magnetic thickness gauge reflects its thickness by measuring the change of magnetic attraction between the permanent magnet (probe) and the substrate due to the existence of the plating or by measuring the change of magnetic resistance between the plating and the substrate. 5 Device
This device is a special instrument designed according to the principle described in Chapter 1. The instrument designed with magnetic principle has different measurement ranges for the two types of bond layers: the maximum thickness of Class A plating is 50m; the maximum measurement thickness of Class B plating is 25m.
The instrument designed with magnetic resistance principle has basically the same measurement range for the two types of plating; the maximum measurement thickness is 1tn. 6 Factors affecting the measurement of sugar content
The following factors may affect the measurement accuracy of the bond layer. 6.1 Coating thickness www.bzxz.net
The measurement accuracy is related to the design of the instrument and varies with the coating thickness. For thin coatings, the accuracy is independent of the coating thickness. For thick coatings, the accuracy is an approximate fixed ratio of the thickness. Approved by the State Administration of Technical Supervision in 1992-11~04 and implemented in 1993-08-01
6.2 Magnetism of base metal (type A coating) CE/T 13744-- 92
Thickness measurements made by the magnetic method are affected by changes in the magnetism of the base metal. In practice, this effect is extremely small for low carbon steel. 6.3 Base Metal Thickness (Type A Coating)
For each instrument there is a critical base metal thickness, above which the measurement will not be affected by increases in base metal thickness. Since this thickness depends on the properties of the instrument probe and the base metal, its value should be determined experimentally unless otherwise specified. 6.4 Edge Effect
This method is sensitive to sudden changes in the surface shape of the piece being measured. Therefore, measurements near edges or internal corners are invalid unless the instrument has been calibrated there. Depending on the instrument, , this effect can extend about 20mm from the mutation point. 6.5 Curvature
The measurement result is affected by the curvature of the measured piece. When the radius of curvature decreases, this effect is more significant. And it varies greatly with the type and model of the instrument.
For instruments with double-pole probes, different readings will be produced when the arrangement direction of the two poles is parallel or perpendicular to the axis of the circle. For single-pole probes, if there is irregular wear, similar phenomena will occur. Therefore, the instrument can only be effectively measured on curved parts after calibration.
6.6 Surface roughness
A series of measurements performed on the same reference surface on a rough surface If the variation of the measured value exceeds the inherent repeatability of the instrument, the number of measurements shall be increased by at least five times.
6.7 Direction of machining of base metal (Type A coating) When using an instrument with a double-pole probe or a single-pole probe with irregular wear, the direction of the machining force (such as rolling) of the base metal will affect the measurement results, and the reading will vary with the direction of the probe on the surface of the measured part. 6.8 Residual magnetism (Type A coating)
The residual magnetism of the base metal will affect the measurement results of instruments using a constant magnetic field, but will have little effect on the measurement results of instruments using a time-varying field.
6.9 Magnetic field
The strong magnetic field generated by various electrical equipment will seriously interfere with the measurement results of instruments using a constant magnetic field. The work of the field instrument. 6.10 Attachments
The instrument probe must be in close contact with the surface of the measured object. Attachments will prevent the probe from being in close contact with the coating, so the probe and the surface of the measured object should be cleaned.
6.11 Magnetism of the coating
The change of the magnetism of the coating will affect the measurement results, and its degree depends on the electroplating conditions, the composition and type of the bonding layer, and the stress state. Dark nickel (no or basically sulfur-free) of the same composition can be made magnetically uniform after heat treatment at 400℃ for 30min. Bright nickel may not be magnetically uniform after heat treatment, and heat treatment may also damage the workpiece. The magnetism of multi-layer nickel coating also depends on the relative thickness of each layer. 6.12 The influence of the nickel coating on the back of the substrate (type B coating) on ​​the measurement results depends on the thickness of the substrate. 6.13 Pressure of the probe
The magnetic pole of the probe should have sufficient constant pressure on the measuring surface, but it should not cause the coating to deform. 6.14 Directionality of the probe
The readings of instruments using the principle of magnetic attraction will be affected by the direction of the magnet relative to the earth's magnetic field. Therefore, the direction of the probe during measurement should be consistent with the direction during calibration.
7 Calibration of instruments
7.1 Calibration
Each instrument must be calibrated before use using appropriate calibration standards in accordance with the manufacturer's instructions. CB/T13744-92
During use, due attention should be paid to the factors in Chapter 6 and the procedures in Chapter 8. 7.2 Calibration standards
7.2.1 The calibration standard should be made of a firmly bonded nickel coating on a substrate. The substrate and coating of the standard should have the same magnetic properties and surface roughness as the test specimen (see 6.2 and 6.6). In order to confirm whether the substrate magnetism is the same, it is recommended to compare the readings of the base metal of the uncoated standard and the unbonded test specimen. Similarly, in order to ensure the correct calibration of the instrument, it is necessary to use a representative sample as a calibration standard, whose thickness has been determined by the coulometric method (see GB4955) or the microscopic method (GB6462). 7.2.2 In some cases, the probe should be rotated 90° to calibrate the instrument (see 6.7 and 6.8). 7.2.3 For Class A coatings, if the critical thickness does not exceed the provisions of 6.3, the base metal thickness of the sample and the calibration standard should be the same. If there is a bond layer on both sides of the base metal, additional errors will be generated. If the critical thickness is not exceeded, the base metal of the calibration standard or sample can be padded with a sufficient thickness of the same material to make the reading independent of the base metal thickness. 7.2.4 If the curvature of the coating to be measured is so small that it cannot be calibrated on a flat surface, the curvature of the coated standard must be the same as the curvature of the sample. 8 Measurement Procedure
The following precautions must be observed during measurement. 8.1 When operating the instrument, due attention should be paid to the factors listed in Chapter 6. 8.2 Base metal thickness (Type A coating):
Check whether the base metal thickness exceeds the critical thickness. If not, measure using the method described in 7.2.3, or ensure that the instrument has been calibrated with a standard sheet with the same thickness and magnetic properties as the specimen. 8.3 Edge greening:
Do not measure near non-continuous areas such as corners, holes, and inner corners of the specimen unless calibration has been performed there. 8.4 Curvature:
Do not measure on the curved surface of the specimen unless calibration has been performed on the curved surface. 8.5 Number of readings:
Since the readings of conventional instruments are not exactly the same each time, several readings must be taken at each position in each measurement area. Local differences in coating thickness also require that measurements be taken on the specified surface, especially when the surface is rough. Magnetic attraction type instruments are very sensitive to vibrations, and readings that are obviously too high should be discarded.
8.6 Direction of machining (Type A coating): If the direction of machining has a significant effect on the reading, the direction of the probe should be consistent with the direction used for calibration when measuring on the specimen. Otherwise, the probe should be rotated 90° for a maximum of four measurements in the same measuring area. 8.7 Residual magnetism:
When using a double-pole measuring instrument with a constant magnetic field, if the base metal has residual magnetism, the measurement must be made in two opposite directions (180\). In order to obtain correct results, the specimen should be demagnetized. 8.8 Surface cleanliness:
: Before measuring, remove attachments such as dust, grease and corrosion from the surface, but do not remove any plating. When measuring, avoid any area with visible defects such as weld ripples, acid stains, iron scale or oxide scale that are difficult to remove. B.9 Tips:
The measurement results are related to the operator's skills. For example, the pressure of the probe, or the size and rate of the balancing force applied to the magnet vary from person to person. However, if the instrument is calibrated by the same measurement person, this effect can be minimized by using a constant pressure probe for measurement. 8.10 Probe position;
The probe should be placed vertically on the measuring point on the surface of the specimen, which is important for magnetic attraction instruments. However, the probe of some instruments can be slightly tilted to obtain the minimum reading. On smooth surfaces, if the reading changes significantly with the tilt angle, the probe may be worn and replaced. When using a magnetic attraction instrument for horizontal measurement or inverted measurement, when the position of the measuring system is not at the center of gravity, it must be calibrated separately.
9 Accuracy requirements
GB/T13744—92
The calibration and measurement of the instrument should be such that the error between the measured coating thickness and the actual thickness is within 10% or 1.5um. Whichever is larger, better accuracy can be obtained. Additional notes,
This standard is proposed by the Ministry of Machinery and Electronics of the People's Republic of China. This standard is under the jurisdiction of Shenyang Instrument and Meter Technology Research Institute. This standard was drafted by Shenyang Instrument and Meter Technology Research Institute. The main drafters of this standard are Wang Xingku and Li Yinqi.
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