JB/T 5068-1991 X-ray spectrometry method for measuring thickness of metal coatings
Some standard content:
GB/T16921-1997
This standard is formulated based on ISO3497:1990 "Metallic Coating Thickness Measurement by X-ray Spectrometry". It is equivalent to the international standard in terms of technical content and is basically the same in terms of writing rules. Compared with ISO3497:1990, this standard is different in the table of contents and chapter arrangement of Chapters 6 and 7, but the content and order remain unchanged.
Appendix A of this standard is the appendix of the standard.
This standard replaces JB/T5068-91 "Metallic Coating Thickness Measurement by X-ray Spectrometry" from the date of its release and implementation.
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Metallic and Non-metallic Coatings. The drafting unit of this standard: Wuhan Institute of Materials Protection, Ministry of Machinery Industry. The main drafter of this standard: Zhu Biesheng.
GB/T169211997
ISO Foreword
ISO (International Organization for Standardization) is a worldwide union of national standards bodies (ISO member bodies). The work of formulating international standards is generally carried out through ISO technical committees. If each member body is interested in a topic determined by a technical committee, it has the right to make a statement to the committee. Governmental and non-governmental international organizations associated with ISO can also participate in the work. In all aspects of electrotechnical standardization, ISO works closely with the International Electrotechnical Commission (IEC).
The draft international standard adopted by the technical committee is sent to the member bodies for approval before it is adopted as an international standard by the ISO Council. According to ISO procedures, at least 75% of the member bodies participating in the voting must approve it before it is published as an international standard. International Standard ISO3497 was developed by ISO/TC107 Technical Committee on Metallic and Other Inorganic Coatings. This second edition replaces and cancels the first edition (ISO3497:1976) and is its technical revision. Appendix A is an integral part of this international standard. 267
1 Scope
National Standard of the People's Republic of China
Metallic coating
Thickness measurement
X-ray spectrometric method
Measurement of metallic coating thicknessX-ray spectrometric methods
This standard specifies the X-ray spectrometric method for measuring the thickness of metallic coatings, GB/T169211997
eqvISO3497:1990
The method specified in this standard is a non-contact non-destructive thickness measurement method that can measure some three-layer systems simultaneously. The measurement method used in this standard basically belongs to a method for determining the mass per unit area. If the density of the coating material is known, the measurement result can also be expressed as the linear thickness of the coating. The actual thickness measurement range of the coating material mainly depends on the allowable measurement uncertainty. And it varies with the instruments and operating conditions used. The typical measurement range of commonly used metallic coating materials is shown in Appendix A (Standard Appendix). 2 Definitions
This standard adopts the following definitions.
2.1X-ray fluorescence (XRF)
Secondary radiation generated by high-energy incident X-rays irradiating a material. This secondary radiation has the wavelength and energy characteristics of the material. 2.2Fluorescence radiation intensity
Radiation intensity measured by the instrument expressed in counts per second (radiation pulses). 2.3Normalized intensity (1.)
Normalized fluorescence radiation intensity. The normalized intensity is independent of the measuring instrument, measuring time, and excitation radiation intensity. However, the geometric structure of the measuring system and the excitation radiation energy affect the normalized count rate.
Normalized intensity 1. is given by formula (1):
Where I. Fluorescence radiation intensity measured on the cover layer sample; I. Fluorescence radiation intensity measured on the uncoated substrate material; 1. Fluorescence radiation intensity measured on the coating material with a thickness greater than or equal to the saturation thickness; 1., l., l. are measured under the same conditions. 2.4 Saturation thickness
. (1)
The minimum thickness at which the fluorescence radiation intensity of a material no longer changes detectably with the increase in the thickness of the material under certain conditions. Note 1: The saturation thickness depends on the energy or wavelength of the fluorescence radiation, the density and atomic number of the material, and the relationship between the incident angle, the fluorescence emission and the surface of the material. 2.5 Intermediate covering layer
A covering layer located between the surface covering layer and the base material, whose thickness should be less than the saturation thickness of each layer. Note 2 In the measurement, any intermediate covering layer with a thickness exceeding the saturation thickness can be regarded as the true base. Approved by the State Administration of Technical Supervision on July 25, 1997 268
Implementation on February 1, 1998
2.6 Count rate
GB/T16921—1997
The number of fluorescence radiation pulses recorded by the instrument per unit time. 3 Principle
3.1 Basic Principle
There is a certain relationship between the mass per unit area of the coating (or the linear thickness of the coating if the density is known) and the intensity of the secondary radiation generated. Through any practical detection instrument, first use a standard combination of known mass per unit area (or thickness) to draw a relationship curve, and then measure the radiation intensity of the sample to be tested under the same conditions. Through the relationship curve, the mass per unit area (or thickness) of the coating is obtained. The density of the coating material is the density of the coating state, not necessarily the theoretical density of the coating material during measurement. The fluorescence intensity is a function of the atomic number of the element. The coating (including the intermediate coating) and the substrate with different atomic numbers will produce their own characteristic radiation. By selecting one or more energy bands and adjusting the appropriate detection system, the surface coating and the intermediate coating can be measured simultaneously. 3.2 Excitation
3.2.1 Overview
The determination of metal coating thickness by X-ray spectrometry is based on the fact that a strong and narrow beam of polychromatic or monochromatic X-rays is irradiated onto the substrate and coating to produce secondary radiation of different wavelengths or energies. These secondary radiations have the characteristics of the elements constituting the coating and substrate. Usually, a high-voltage X-ray tube generator or an appropriate radioactive isotope is used to excite the secondary radiation. 3.2.2 High-voltage X-ray Tube Excitation
The excitation is generated by the X-rays generated by an X-ray tube with an external high voltage under stable conditions and irradiated onto the sample to be measured through a collimator. It can provide a high radiation intensity. It can measure a very small area, and the control and safety protection are relatively easy. 3.2.3 Radioactive Isotope Excitation
The excitation is generated by selecting a suitable radioactive isotope source and irradiating it onto the sample to be measured through a collimator. The energy of the ideal excitation ray should be slightly higher than the required characteristic X-ray energy. Only a few radioactive isotopes emit gamma rays that are included in the energy band suitable for coating thickness measurement. The radioisotope excited instrument has a compact structure, does not require a cooling device, and provides basically monochromatic radiation with low background intensity. However, its radiation intensity is low, so it cannot measure small areas, and its life span is short. Pay attention to personal protection when using high-intensity isotope sources. 3.3 Dispersion
3.3.1 Overview
The secondary radiation generated by X-ray irradiation on the surface of the coating usually contains multiple wavelengths or energies. Wavelength dispersion and energy dispersion can be used to separate the components required for the measurement of the coating thickness. 3.3.2 Wavelength dispersion
Use a crystal spectrometer to separate the characteristic wavelength of the coating or substrate. 3.3.3 Energy dispersion
Use a discriminator or energy analyzer to separate the radiation energy of the coating or substrate. X-ray quanta are usually expressed in wavelength or equivalent energy. The relationship between them is ·E=1.2396
Where: ^-wavelength, nm;
E-energy, keV.
3.4 Detection
Wavelength dispersion systems are usually detected using gas proportional counters and scintillation counters. Energy dispersion systems are usually detected using proportional counters and multi-channel analyzers. 3.5 Thickness measurement
3.5.1 Thickness measurement method
There are two X-ray thickness measurement methods:
(2)
GB/T16921—1997
a) Emission method This is a thickness measurement method that measures the characteristic radiation intensity of the covering layer. When the thickness of the covering layer is less than the saturation thickness, this intensity will increase with the increase of the thickness of the covering layer [see Figure 1a)]. b) Absorption method This is a thickness measurement method that measures the characteristic radiation intensity of the substrate. The rays that pass through the covering layer are attenuated due to absorption by the covering layer. Therefore, when the thickness of the covering layer is less than the saturation thickness, its intensity decreases with the increase of the thickness of the covering layer [see Figure 1b)]. When using the absorption method for actual measurement, ensure that there is no intermediate covering layer. The absorption characteristic curve is similar to the emission characteristic curve in reverse. The emission method can also be combined with the absorption method to measure the thickness by the ratio of the characteristic radiation intensity of the covering layer and the substrate. This method basically eliminates the influence of the distance between the test sample and the detector. Value
Thickness of cover layer
a) X-ray emission method
Thickness of cover layer
b) X-ray absorption method
Figure 1 Relationship between count rate intensity and cover layer thickness 3.5.2 Relationship curve
In all methods, the fluorescence radiation intensity is obtained by measuring the cumulative pulse value of a certain preset time. Most of the applicable instruments currently sold directly use the normalized count rate system. It can be seen from formula (1) that the normalized count rate of the substrate without cover layer greater than the saturation thickness is 0, while the normalized count rate of the cover layer greater than the saturation thickness is 1. Therefore, all measurable thickness count rates are within the normalized count rate range of 0 to 1. The relationship curve between the unit area mass of the cover layer and the normalized count rate of fluorescence radiation is shown in Figure 2. Linear range
Logarithmic range
Normalized count rate
Hyperbolic range
Figure 2 Relationship between unit area mass and normalized count rate03 Saturated base material without coating
Count rate of material
Count rate of saturated thickness coating material
As shown in Figure 2, when measuring, samples with normalized count rate in the range of 0.3 to 0.8 can achieve the best sensitivity and measurement accuracy in the entire thickness measurement range by calibrating with thickness standard blocks. When measuring thickness values in other areas, due to thickness changes, the relative uncertainty of the same thickness standard block may increase. At this time, some other applicable standard blocks with lower measurement uncertainty should be used and added to establish the correct mathematical relationship to ensure measurement accuracy. When measuring a combination of coating/matrix materials with large energy differences (energy dispersion systems), when the characteristic count rate ratio of the saturated coating to the uncoated substrate is very high (typically 10:1), a calibration standard with a similar or identical substrate is not necessarily required (because the substrate material does not radiate in the same energy band as the coating material). When measuring a combination of coating/matrix materials with similar energies, when the characteristic count rate ratio of the saturated coating to the uncoated substrate is 1:3, it is often necessary to select a suitable "filter" that selectively absorbs the radiation of a certain material (usually the substrate) and allows most of the radiation of the other material to pass smoothly, thereby improving the measurement accuracy. This filter is usually placed manually or automatically between the surface being tested and the detector. 3.6 Multilayer Thickness Measurement
When the characteristic X-ray radiation of the inner layer of the coating is not completely absorbed by the outer layer, both the inner layer and the outer layer can be measured. This requires the installation of an energy dispersion device with a multi-channel analyzer to simultaneously receive the characteristic energy bands of the multilayer coating. 3.7 Alloy Layer Thickness Measurement
The thickness of some alloy or compound coatings can also be measured by X-ray spectroscopy, but the composition must be known or determined before thickness measurement or its composition can be measured.
Note 3: The determined composition will introduce measurement errors. Some coatings will form alloys through mutual diffusion with the substrate. The existence of these alloy layers will increase the measurement uncertainty.
4 Instrument
The X-ray thickness measurement device that meets the standards is generally composed of an energy dispersion device and a microprocessor. The microprocessor converts the radiation intensity into mass per unit area or thickness, and can store standard data and perform various measurement statistics. The main components of the thickness measurement device include a primary X-ray source, a collimator, a sample stage, a detector and an evaluation system (see Figure 3). Note 4: When necessary, special software, electronic filtering or physical filters are required to separate, filter or absorb the fluorescence energy of one or more materials. The introduction of these devices can enhance the fluorescence of the material being tested, thereby reducing the measurement uncertainty. X-ray tube
Test sample
Filter
Detector
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X-ray tube
a) X-ray tubewwW.bzxz.Net
4.1 Primary X-ray source
Collimator
Filter.
Test sample
Detector
Radioisotope
Collimator
Test sample
c) Radioisotope Primary X-ray laser
Figure 3 Illustration of the main components of the energy dispersion system Collimator
Filter
b) X-ray tube
Detector
GB/T16921---1997
Usually an X-ray tube or an appropriate radioisotope is used to excite the fluorescence radiation used for measurement. 4.2 Collimator
Collimator is a single or multiple hole with precise size for X-rays to pass through. These holes can theoretically be of any shape, but the size and shape of the hole will determine the size of the incident X-ray beam on the surface of the cover to be tested. Existing commercial instruments generally use round, square or rectangular hole collimators.
4.3 Detector
A device used to receive the fluorescence radiation of the sample to be tested and convert it into a measurable electrical signal. It can select the characteristic energy spectrum of one or more surface coatings, intermediate coatings and base materials. 4.4 Evaluation system
A software program configured according to the instrument design processes the acquired data to determine the mass per unit area or thickness of the coating layer of the sample to be tested. 5 Factors affecting the measurement results
5.1 Counting statistics
5.1.1 Overview
Since the generation of X-ray photons is completely random, the number of emitted photons in a fixed time interval is not the same, so statistical errors are generated. This statistical error always exists in all radiation measurements. The counting rate of a short time interval may differ greatly from the counting rate of a long time interval, especially when the counting rate is low. To reduce the counting statistical error to an acceptable level, a properly long counting period must be used to accumulate enough counts. Statistical errors are independent of other errors.
5.1.2 Standard Deviation of Counts
The standard deviation S of the random error in counting is very close to the square root of the total counts N, that is: SN
where: N is the number of counts at a given time.
In all measurements, the correct counts within the range of N (1 ± 1) can be obtained in 95% of the cases. N
5.1.3 Standard Deviation of Thickness
**. (3)
The standard deviation of thickness measurement is different from the standard deviation of counting, but there is a certain functional relationship. It depends on the slope of the calibration curve at the measurement point. The standard deviation of most commercially available X-ray fluorescence thickness gauges is expressed in thickness units or as a percentage of the average thickness. 5.2 Calibration Standard Blocks
When measuring thickness, it is necessary to calibrate with a thickness calibration standard block. The uncertainty of the standard block should generally be less than 5%, but it is very difficult to ensure an uncertainty of 5% for thin coatings or due to roughness, porosity and diffusion. The calibration standard block can only be used when the normalized count rate of the coating is within the thickness measurement range of 0.05 to 0.9. 5.3 Coating thickness
The coating thickness range affects the measurement uncertainty. In the curve of Figure 2, the measurement accuracy is highest in the 0.3 to 0.8 logarithmic region. In other regions, the measurement accuracy will be significantly reduced. Generally speaking, the thickness measurement limit range is different for different coating materials. 5.4 Measuring area
The measuring area is determined by the size of the collimator aperture. In order to obtain satisfactory statistical counts in a short counting period (see 5.1), a collimator aperture that is commensurate with the shape and size of the specimen should be selected to obtain the largest possible measuring area. The area of the collimator hole should generally not be larger than the area available for measurement on the coating surface. However, in some special cases, the measured area can be smaller than the beam area (see 5.11). However, it must be noted that the measuring area should not be unable to obtain correct measurement results due to the generation of saturated count rates. Calibration must be performed on areas of the same size. 5.5 Composition of the coating
GB/T16921-1997
Foreign inclusions, co-precipitates or alloy layers formed by expansion at the interface between the substrate and the coating in the coating will affect the measurement of the mass per unit area. The measurement of thickness is also affected by voids and pores. These errors can be eliminated by using calibration standard blocks prepared under the same conditions as the coating and produced by representative characteristic X-rays. Since the presence of inclusions, pores or voids leads to different densities, the coating with these defects is best measured by the mass per unit area. If the density of the coating to be measured is known, it can be input into the measuring instrument for correction (see 5.6).
5.6 Density of the coating
If the density of the coating sample material is different from that of the calibration standard block, a corresponding error will be generated when measuring the thickness. When the density of the coating material is known, this error can be eliminated and the thickness value can be obtained (see 3.1). If the measurement is in units of mass per unit area, the linear thickness d can be obtained by dividing the measured value PA by the density of the covering layer P2. If the measurement is in linear units, the density-corrected thickness formula is: d = due
Where: d - linear thickness, μm
dg - linear thickness reading, μm;
Pi - density of the covering material of the thickness calibration standard block, g/cm2; P - - density of the covering material of the test specimen, g/cm2; Pa - mass per unit area of the covering layer of the test specimen, mg/ctn. 5.7 Matrix composition
.... (4)
(5)
When measuring thickness by X-ray emission method, the influence of matrix composition on the measurement result can be ignored under the following conditions: a) The wavelength of the fluorescent X-ray emitted by the matrix does not intrude into the characteristic energy band of the fluorescent radiation of the selected covering layer. If it intrudes, measures should be taken to eliminate its influence.
b) The fluorescent X-rays of the substrate material cannot excite the coating material. c) Use the intensity ratio method (see 3.5) When measuring thickness by X-ray absorption method, the matrix composition of the calibration standard block and the reference standard block should be the same as the matrix composition of the sample.
5.8 Matrix thickness
When measuring thickness by X-ray emission method, the substrate of the double-sided coating sample should be thick enough to prevent the reverse coating from generating interference. When measuring thickness by X-ray absorption method, the substrate thickness should be equal to or greater than its saturation thickness, otherwise the instrument must be calibrated with a reference standard block of the same substrate thickness (see 6.3).
5.9 Surface cleanliness
The attached materials on the surface of the measured coating, such as dust, grease or corrosion products, protective layer, and surface treatment layer, will cause measurement errors. 5.10 Intermediate coating
When the absorption characteristics of the intermediate coating are unclear, the absorption method cannot be used, and the emission method is recommended. 5.11 Specimen curvature
When measuring the thickness of a coating on a curved surface, a collimator aperture of suitable shape and size should be selected to minimize the effect of the surface curvature. For example, in practice, a rectangular aperture collimator is preferred for measuring the surface of a cylinder. In general, a collimator with a smaller aperture should be selected whenever the measurement allows, to reduce the effect of the curvature of the plane.
If calibration is performed using a standard block of the same size or shape as the specimen, the effect of the specimen curvature will be eliminated, but the measurement must be performed at the same location, on the same surface and on the same measurement area of the sample. In this case, it is possible to use a collimator aperture with an area larger than that of the test specimen. 5.12 Excitation energy and excitation intensity
GB/T16921-1997
Since the intensity of fluorescence radiation depends on the excitation energy and excitation intensity, the instrument used must be able to stably provide X-rays with the same excitation energy and excitation intensity during calibration and measurement. 5.13 Detector
An unstable or abnormal operation of the detector system can also introduce measurement errors. Therefore, before use, the instrument must be subjected to stability tests using automatic or manual methods.
During the test, a single reference piece or sample is placed on a sample table irradiated by X-rays. The sample is not moved during the entire test process. According to the test requirements, a series of single count rate measurements are made within a short period of time. The standard deviation of the series should not be significantly greater than the square root of the average value of the series. In order to confirm the stability over a longer period of time, the above results can be compared with the results obtained previously at the same time. The stability of that period is determined by the time used for a single measurement series or the interval time required between two independent measurement series. 5.14 Radiation path
Since the loss of radiation in the path will increase the measurement error, the radiation path should be as short as possible. When measuring elements with an atomic number less than 20, since sufficient radiation intensity cannot be excited under air conditions to meet the requirements of the type of instrument shown in Figure 3, it is necessary to perform the spectrometry under vacuum or nitrogen conditions.
5.15 Conversion of count rate to unit area mass or thickness In addition to direct manual calculation, commercial instruments generally use microprocessors to convert count rates to unit area mass or thickness. The microprocessor often has a main program derived by mathematical methods. After inputting the data of appropriate calibration or reference standard blocks, the program can meet the actual requirements of the test. The reliability of the conversion depends on the correctness of the standard curve, equation, calculation method and other conversion methods, and also on the quality, quantity and thickness calibration value of the calibration standard blocks at the corresponding points when measuring thickness. When a certain covering layer causes other layers to produce additional fluorescence, the conversion method should take this into account. Extrapolation within the thickness range determined by the calibration standard block may lead to large errors. 5.16 Inclination of the sample surface
When measuring, if the inclination of the surface to be measured relative to the incident X-ray beam is different from that when the calibration standard block is used, the count rate will change significantly, causing measurement errors. For example, a difference of 10° in inclination can result in a 4% change in the count rate. 6 Calibration of the instrument
6.1 Overview
6.1.1 General requirements
Instrument calibration should be carried out in accordance with the instrument manual, and appropriate consideration should be given to the factors described in Chapter 5 and the requirements in Chapter 8. The instrument shall be calibrated at least once a day using thickness standards of the same system as the coating/substrate to be measured. If the measured thickness value is obviously not in compliance with the requirements of Chapter 8, the instrument shall be recalibrated. 6.2 Calibration Methods
6.2.1 Linear Range Calibration
For measuring thin coatings, which are generally within the linear range with a normalized count rate below 0.3, it is recommended to calibrate using an uncovered substrate and a single coating thickness standard block of known thickness within the linear range. 6.2.2 Logarithmic Range Calibration
When calibrating thickness measurements in this range, at least a set of four standard blocks must usually be used: an uncovered substrate material standard block, a coating material standard block of at least the saturation thickness, a coating standard block with a thickness close to or at the lower limit of the logarithmic range, and a coating standard block with a thickness close to the upper limit of the logarithmic range. 6.2.3 Calibration of the entire measuring range
For the calibration of the entire measuring range from 0 to the thickness of the hyperbolic range, it is necessary to add a coating standard block with a thickness close to the end value of the limited range for calibration.
When measuring thin coatings, the instrument that has been fully calibrated can interpolate between the zero value and the minimum thickness value of the standard block. However, when measuring thick coatings, if the maximum thickness value of the standard block is exceeded, it is generally not necessary to extrapolate, otherwise unreliable results may result (see 5.2). 274
6.3 Standard blocks
6.3.1 General requirements
GB/T16921-1997
The standard block for calibrating the instrument must be reliable. The uncertainty of thickness measurement depends directly on the uncertainty of the standard block and the measurement accuracy. The standard block should have a uniform coating with a known mass or thickness per unit area, and the coating thickness on its effective surface should not exceed ±5% of the specified value. It is only reliable when it is used for coatings of the same composition or known density. When measuring coatings of alloy composition, the composition of the calibration standard block does not need to be the same, but should be known. 6.3.2 Foil Standards
If a metal foil is attached to a suitable substrate as a standard, care must be taken to ensure that the contact surface is clean and free of wrinkles and kinks. If there is a density difference, it must be compensated before measurement unless the measurement allows it. 6.4 Selection of Standard Blocks
The instrument can be calibrated using the unit area mass or thickness value of the standard block, but the influence of density must be considered. Although the instrument design allows some deviation from the ideal situation (see 3.1), the standard block must have the same or very similar coating and substrate materials as the test sample. 6.5 X-ray Emission (or Absorption) Characteristics of Standard Blocks The coating of the thickness standard block should have the same emission (or absorption) characteristics as the coating of the sample to be tested. If the thickness is measured by X-ray absorption method and intensity ratio method, the substrate of the thickness standard block should also have the same emission (or absorption) characteristics as the substrate of the sample to be tested. 6.6 Matrix Thickness
When the matrix thickness is less than its saturation thickness, the X-ray absorption method is generally used. In this case, the matrix thickness of the sample and the calibration standard block should be the same.
7 Measurement Procedure
7.1 General Requirements
Operate the instrument for measurement according to the instrument manual, and appropriately consider the factors listed in Chapter 5 and the accuracy requirements of 6.3 and Chapter 8. 7.2 Notes
7.2.1 Selection of collimator or aperture
Select the collimator or aperture according to the shape of the sample and the effective test area. The distance between the collimator aperture and the sample should remain unchanged during the test.
7.2.2 Curved Surface Measurement
When measuring a curved surface, if a sufficiently small collimator hole can be selected so that the characteristics of the curved surface being tested are approximately consistent with a flat surface, the measurement can be calibrated with a flat thickness standard block. Otherwise, the requirements of 5.4 and 5.11 should be considered. 7.2.3 Calibration
To ensure that the instrument and measurement conditions remain unchanged, the instrument should be calibrated at specified time intervals according to the requirements of the instrument manual. 7.2.4 Measurement time
Since the measurement uncertainty depends on the measurement time, a sufficient measurement time with an acceptably low measurement uncertainty should be selected. 7.2.5 Number of measurements
The measurement uncertainty is related to the number of measurements. An increase in the number of measurements will reduce the measurement uncertainty. If the number of measurements increases by times, the measurement uncertainty will decrease by one
The standard deviation should be calculated from at least 10 measurements on the same measurement surface. 7.2.6 Protective measures
The relevant issues of operator protection against X-rays should be carried out in accordance with the current relevant national standards and regulations. 7.2.7 Result representation
The conversion of intensity value (count rate) to unit area mass or thickness can be performed automatically by commercially available instruments. For other instruments, a standard curve similar to Figure 1 can be drawn. Generally, the result of unit area mass is expressed in mg/cm. The thickness measurement result is expressed in um. 275
8 Measurement uncertainty
GB/T16921-1997
The calibration and operation of the instrument should make the measurement uncertainty less than 10%. To reduce the measurement uncertainty, you can increase the measurement time, increase the number of measurements, and change the collimator aperture size (until the detector reaches saturation).
Test report
The test report should include the following contents:
a) the number of this standard or the reference standard number; b) the test date;
c) the measuring instrument used;
d) the mark or number of the specimen;
e) the measurement position on the specimen;
f) the average number of measurements;
g) the aperture size of the collimator used for measurement or the size of the measuring area (if the two are different, they must be indicated separately); h) measured values:
i) the density value used for thickness calculation and the reason for using it; j) the standard deviation of the measured values;
k) differences from the method of this standard;
1) factors that may affect the interpretation of the reported results; m) the name of the laboratory and the operator.
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