WO2023045451A1

WO2023045451A1 - Metal oxide ceramic layer thickness measuring system and thickness measuring method window therefor

Info

Publication number: WO2023045451A1
Application number: PCT/CN2022/100719
Authority: WO
Inventors: 俞天白; 姚夏睿; 康伟琦; 李蒙; 常兆华
Original assignee: 苏州微创关节医疗科技有限公司
Priority date: 2021-09-23
Filing date: 2022-06-23
Publication date: 2023-03-30
Also published as: CN113884015A

Abstract

A metal oxide ceramic layer thickness measuring system (101) and a thickness measuring method therefor, the thickness measuring system (101) comprising an infrared light source (1), an interferometer (2), a detector (6) and a data processor (7). Infrared light emitted by the infrared light source (1) passes through the interferometer (2). The interferometer (2) is used to form interference light from interference generated by the infrared light and to transmit the interference light to a test sample. The detector (6) collects reflected light. The data processor (7) is used to receive a reflected light signal transmitted by the detector (6) and outputs an interferogram at a measured position. The thickness measuring system (101) and the thickness measuring method therefor fully utilize change features of the infrared interference optical signal of a metal oxide ceramic layer under different thickness conditions, achieving accurate and rapid nondestructive measurement, and not producing any damage to detected parts; therefore, zirconium and a zirconium alloy surface oxidation layer can be comprehensively inspected, and is not affected by factors such as surface curvature/shape.

Description

Metal Oxide Ceramic Layer Thickness Measurement System and Its Thickness Measurement Method Window

Cross References to Related Applications

This disclosure claims priority to a Chinese patent with application number 2021111152582 filed with the China Patent Office on September 23, 2021, the entire contents of which are incorporated by reference in this disclosure.

technical field

The present application relates to the technical field of thickness detection, in particular to a metal oxide ceramic layer thickness measurement system and a thickness measurement method thereof.

Background technique

Zirconium and zirconium alloys have good mechanical properties, corrosion resistance and small thermal neutron absorption cross-section, and are widely used as nuclear fuel cladding materials for light water reactors and heavy water reactors. In the medical field, zirconium and zirconium alloys have the advantages of good biocompatibility and closer to the elastic modulus of human bone, and are ideal implant materials. However, zirconium and zirconium alloys have poor wear resistance and cannot be directly applied to load-bearing artificial joint prostheses such as hip and knee joints. and other risks, it is necessary to improve the friction and wear properties of zirconium and zirconium alloy surfaces.

In the prior art, by oxidizing zirconium and zirconium alloys in air, a layer of dense and high-hardness oxide ceramic layer can be formed on the outer surface of the alloy, which significantly improves the wear resistance of zirconium and zirconium alloys. A large number of studies have shown that the thickness of the oxide ceramic layer determines the quality of the oxide ceramic layer. If the surface oxide ceramic layer is too thick, a large number of microcracks will be generated inside the oxide ceramic layer to reduce the bonding strength with the substrate. If the oxide ceramic layer is too thin, it will cause Oxide ceramic layers have a shorter service life. Therefore, when zirconium and zirconium alloys after thermal oxidation are applied to artificial joint prosthesis, the thickness of the oxide ceramic layer is a key indicator of the safety of the prosthesis, and it is the quality that needs to be controlled during the preparation of the oxide ceramic layer and the use of the prosthesis. ensure.

In addition, when zirconium and zirconium alloys are applied to load-bearing artificial joint prostheses such as hip and knee joints, in order to reduce the friction coefficient of the articular surface to reduce wear, it is necessary to reduce the roughness of the surface oxide ceramic layer as much as possible. The layer is finely polished, but the polishing process will cause a certain loss in the thickness of the oxide ceramic layer. Therefore, from the preparation of the oxide ceramic layer to the fine polishing, it is necessary to quantitatively characterize the thickness of the oxide ceramic layer.

Although the commonly used detection methods such as metallographic method, scanning electron microscope observation method and electrolytic thickness measurement method have high accuracy, they are destructive to a certain extent.

Contents of the invention

Based on this, it is necessary to provide a metal oxide ceramic layer thickness measurement system and a thickness measurement method thereof that will not cause damage (non-destructive) to the metal oxide ceramic layer in view of the above technical problems.

A metal oxide ceramic layer thickness measurement system, the metal oxide ceramic layer thickness measurement system comprises:

an infrared light source for providing infrared light;

an interferometer, configured to interfere the infrared light to form interference light, and direct the interference light to the test sample;

a detector for collecting reflected light reflected from said test sample; and

The data processor is used to receive the reflected light signal transmitted by the detector, and output the interferogram at the measured position to obtain the thickness of the metal oxide ceramic layer.

In one of the embodiments, a microscope is also included, the microscope is used for receiving the interference light formed by the interferometer, and directing the interference light toward the sample.

In one of the embodiments, the microscope includes a stage and a light source, the stage is used to carry the sample, and the position of the light source can be adjusted to carry out the measurement on the surface of the sample to be measured. Focusing, the optical path of the light source is used to share with the interference light.

In one of the embodiments, it also includes an adjustment fixture, the adjustment fixture is arranged on the stage, the adjustment fixture is used to clamp the sample to be tested, the adjustment fixture includes a clamping part and an adjustment knob, the The adjusting knob is screwed on the clamping part, and the inner diameter of the clamping part can be adjusted through the adjusting knob.

A method for measuring the thickness of a metal oxide ceramic layer thickness measuring system, comprising the following steps:

Interfering the infrared light emitted by the infrared light source through the interferometer to form interference light;

The formed interference light is irradiated on the sample to be tested, the reflected light reflected from the measured position of the sample to be tested is collected by a detector, and the reflected light signal is transmitted to a data processor, and the data processor outputs the The interferogram at the measured position of the sample to be tested is obtained to obtain the thickness of the metal oxide ceramic layer.

In one of the embodiments, the average wave difference value within a predetermined wavenumber range is calculated according to the shown interferogram and substituted into the calculation formula for the thickness d of the oxide ceramic layer to obtain the thickness d of the oxide ceramic layer of the sample to be tested, so The calculation formula of the oxide ceramic layer thickness d is as follows:

in,

Indicates the average wave difference value within the predetermined wavenumber range in the interferogram at the measured position of the sample to be tested; a and b are constants measured in advance by the standard sample.

In one of the embodiments, the measuring method of the constants a and b is as follows:

Provide at least three standard test samples, the thickness d of the oxide ceramic layer of the at least three standard test samples is different, and the thickness d of the oxide ceramic layer is known;

The formed interference light is irradiated to the standard test sample, the reflected light reflected from the measured position of the standard test sample is collected by a detector, and the reflected light signal is transmitted to the data processor, the The data processor outputs the interferogram at the measured position of the standard sample, so that multiple positions of each standard sample are tested to obtain the interferogram respectively;

Calculates the average wave difference over a predetermined wave number range

The oxide ceramic layer thickness d and the average wave difference

Substitute into the following formulas for fitting to obtain the values of constants a and b:

In one of the embodiments, the predetermined wavenumber range is a continuous wavenumber range selected within the wavenumber range of 2100cm ⁻¹ to 1000cm ⁻¹ in the interferogram.

In one embodiment, the values of the constants a and b are respectively: a=2500-3000, b=-1.08--1.05.

In one of the embodiments, the thickness d of the oxide ceramic layer of the standard test sample is measured by a scanning electron microscope.

In one of the embodiments, the average wave difference

The calculation method is: taking each adjacent trough in the predetermined wave number range as a cycle, subtracting the wave values corresponding to the troughs at both ends of the predetermined wave number range to obtain a difference, and then dividing the difference by the predetermined wave number The number of cycles within the range, which is the average wave difference value within the predetermined wave number range

In one embodiment, the infrared light has a wavelength ranging from 2.5 μm to 25 μm, and a wavenumber ranging from 4000 cm ⁻¹ to 650 cm ⁻¹ .

In one of the embodiments, before directing the formed interference light to the sample to be tested, it also includes:

The formed interference light is sent to a correction sheet, the reflected light reflected from the measured position of the correction sheet is collected by a detector, and the reflected light signal is transmitted to a data processor, and the interference drawn by the data processor is illustration as a background.

In one of the embodiments, the correction sheet includes an aluminum sheet.

In one of the embodiments, directing the formed interference light to the sample to be tested specifically includes:

placing the sample to be tested on the stage of the microscope;

Let the interference light enter the microscope, and the light source of the microscope shares the same optical path with the interference light;

Adjusting the position of the light source of the microscope to focus on the surface of the sample to be tested, so that the interference light is focused on the surface of the sample to be tested, and refracted and reflected on the surface.

The above metal oxide ceramic layer thickness measuring system has at least the following advantages:

The infrared light emitted by the infrared light source passes through the interferometer. The interferometer is used to interfere the infrared light to form interference light. The interference light is used to shoot to the test sample, and the detector is used to collect the reflected light reflected from the test sample. The processor is used to receive the reflected light signal transmitted by the detector, and output the interferogram at the measured position. It makes full use of the changing characteristics of the infrared interference light signal of the metal oxide ceramic layer under different thickness conditions, and realizes accurate and fast non-destructive measurement without any damage to the detection part, so it can conduct a comprehensive inspection of the oxide layer on the surface of zirconium and zirconium alloy. And it is not affected by factors such as surface curvature/shape.

Description of drawings

The accompanying drawings constituting a part of the application are used to provide a further understanding of the application, and the schematic embodiments and descriptions of the application are used to explain the application, and do not constitute undue limitations to the application.

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

Fig. 1 is a simple schematic diagram of a metal oxide ceramic layer thickness measuring system in an embodiment;

Fig. 2 is a simple schematic diagram of an adjusting fixture in an embodiment;

Fig. 3 is a flow chart of the thickness measurement method of the metal oxide ceramic layer thickness measurement system in an embodiment;

Fig. 4 is the schematic diagram of reflection and refraction of interference light;

Fig. 5 to Fig. 7 is the scanning electron microscope measurement thickness (shown in the view on the left) and its corresponding interferogram (shown in the view on the right) of 3 planar standard test samples of known different oxide ceramic layer thicknesses;

Figures 8 to 12 are the thicknesses measured by scanning electron microscopy (shown in the left view) and their corresponding interferograms (shown in the right view) of five planar verification test samples with known different oxide ceramic layer thicknesses;

Figures 13 to 17 are the thicknesses measured by scanning electron microscopy (shown in the view on the left) and their corresponding interferograms (shown in the view on the right) of five spherical samples.

Explanation of reference signs:

101. Metal oxide ceramic layer thickness measurement system; 1. Infrared light source; 2. Interferometer; 3. Microscope; 6. Detector; 7. Data processor; 4. Adjusting fixture; 8. Clamping part; 9. Adjusting knob .

Detailed ways

In order to make the above-mentioned purpose, features and advantages of the present application more obvious and understandable, the specific implementation manners of the present application will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, the present application can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

As shown in FIG. 1 , the metal oxide ceramic layer thickness measurement system 101 in one embodiment mainly uses infrared light to perform non-destructive measurement on the oxide ceramic layer of the artificial joint prosthesis, and is used for the entire production process of the artificial joint prosthesis. Grasp the thickness value of the oxide ceramic layer in real time as a quality assurance to improve the safety of the artificial prosthesis, avoid the failure of the artificial joint prosthesis caused by the oxide ceramic layer being too thick or too thin, and reduce the cost and product consumption at the same time. For example, the artificial joint prosthesis can be zirconium and zirconium alloys. By oxidizing zirconium and zirconium alloys in the air, a layer of dense and high-hardness oxide ceramic layer is formed on the outer surface of the alloy, which significantly improves the hardness of zirconium and zirconium alloys. wear resistance. The thickness measurement system 101 for the metal oxide ceramic layer in this embodiment is used to measure the thickness of the zirconium and zirconium alloy oxide ceramic layer.

Specifically, the metal oxide ceramic layer thickness measurement system 101 includes an infrared light source 1 , an interferometer 2 , a microscope 3 , a detector 6 and a data processor 7 . Specifically, the infrared light source 1 is used to provide infrared light. According to the thickness range of the metal oxide ceramic layer to be measured, the wavelength range of the infrared light is selected to be 2.5 μm to 25 μm, and the wave number range is 4000 cm ⁻¹ to 650 cm ⁻¹ .

The interferometer is used to generate interference of infrared light to form interference light, and direct the interference light to the test sample. Specifically, the interferometer 2 includes a beam splitter, a moving mirror and a fixed mirror, and the beam splitter is used to split the infrared light into two beams, one of which is transmitted to the moving mirror, and the other is reflected to the fixed mirror, the two beams of infrared light respectively pass through the moving mirror and the fixed mirror and then return to the beam splitter, the moving mirror moves linearly at a constant speed, so the two beams of infrared light returning to the beam splitter The light forms an optical path difference to generate interference to form interference light, and the interference light is used to irradiate the sample.

The microscope is used to receive the interference light formed by the interferometer, and direct the interference light to the test sample. Specifically, the microscope 3 includes a stage and a light source, the interference light shares the same optical path with the light source after entering the microscope 3, and the stage is used to carry a test sample. Microscope 3 is equipped with wireless correcting eyepieces, which can be used to focus according to the position irradiated by the light source of microscope 3, determine the thickness measurement position of the sample, confirm the detection position more clearly, and make imaging more convenient. The position of the light source can be adjusted to focus on the surface of the sample to be tested, and the light path of the light source is used to share with the interference light. Focusing on the surface of the sample to be tested by adjusting the position of the light source of the microscope 3 actually focuses the interference light on the surface of the sample, and refraction and reflection occur on the surface of the oxide ceramic layer of the sample. Specifically, the light source may be a point light source. Of course, in other implementation manners, the microscope 3 can also be omitted.

Please refer to FIG. 2 , further, in this embodiment, an adjustment jig 4 is also included, the adjustment jig 4 is arranged on the stage, and the adjustment jig 4 is used to clamp the sample to be tested. Specifically, the adjusting fixture 4 includes a clamping portion 8 and an adjusting knob 9, the adjusting knob 9 is screwed on the clamping portion 8, and the inner diameter of the clamping portion 8 can be adjusted by the adjusting knob 9 . For example, the adjusting fixture 4 is developed for complex surfaces to be tested such as spherical or arc surfaces. The adjusting knob 9 fixes the sample, adjusts the stage to complete focusing, and the measuring position is the position indicated by the light source of the microscope 3 . Take the spherical sample as an example, adjust the stage to the initial position, the light source of the microscope 3 is at the center of the stage and the adjustment fixture 4, place the spherical sample in the adjustment fixture 4, and use the microscope 3 to focus , the measured position is the highest point of the spherical sample, and the measurement of other positions can be completed by simply moving the spherical sample.

The detector 6 is used to collect reflected light reflected from the test sample. The detector 6 converts the collected reflected light into a reflected light signal, and the data processor 7 is used to receive the reflected light signal transmitted by the detector 6, and output the interferogram at the measured position to obtain the metal oxide ceramic layer thickness.

The infrared light emitted by the infrared light source 1 passes through the interferometer 2, and the beam splitter of the interferometer 2 divides the infrared light into two beams, one of which is transmitted to the moving mirror, and the other is reflected to the fixed mirror. The two beams of infrared light respectively pass through the moving mirror and the fixed mirror and then return to the beam splitter. The two beams of infrared light returning to the beam splitter form an optical path difference and interfere to form interference light. The interference light is used to shoot to the test sample, the detector 6 is used to collect the reflected light reflected from the test sample, and the data processor 7 is used to receive the reflected light signal transmitted by the detector 6, and output the signal at the measured position. The interferogram to obtain the thickness of the metal oxide ceramic layer. It makes full use of the changing characteristics of the infrared interference light signal of the metal oxide ceramic layer under different thickness conditions, and realizes accurate and fast non-destructive measurement without any damage to the detection part, so it can conduct a comprehensive inspection of the oxide layer on the surface of zirconium and zirconium alloy. And it is not affected by factors such as surface curvature/shape.

The present application also provides a thickness measurement method of a metal oxide ceramic layer thickness measurement system, comprising the following steps:

Step 1. Interfering the infrared light emitted by the infrared light source through an interferometer to form interference light. According to the thickness range of the metal oxide ceramic layer to be measured, the selected wavelength range is 2.5 μm to 25 μm, and the wave number range is 4000 cm ⁻¹ to 650 cm ⁻¹ .

Step 2, shoot the formed interference light onto the sample to be tested, use a detector to collect the reflected light reflected from the measured position of the sample to be tested, and transmit the reflected light signal to the data processor, the data processing The detector outputs the interferogram at the measured position of the sample to be tested, so as to obtain the thickness of the metal oxide ceramic layer.

Step 3. Calculate the average wave difference value within a predetermined wave number range and substitute it into the calculation formula for the thickness d of the oxide ceramic layer to obtain the thickness d of the oxide ceramic layer of the sample to be tested, and the calculation formula for the thickness d of the oxide ceramic layer as follows:

in,

Among them, the measurement methods of constants a and b are as follows:

Step 3-1, providing at least three standard test samples, the thickness d of the oxide ceramic layer of the at least three standard test samples is different, and the thickness d of the oxide ceramic layer is known.

Step 3-2: Interfering the infrared light emitted by the infrared light source through an interferometer to form interference light.

Step 3-3, irradiating the formed interference light to the standard sample, using a detector to collect the reflected light reflected from the measured position of the standard sample, and transmitting the reflected light signal to the data A processor, the data processor outputs the interferogram at the measured position of the standard sample, so that multiple positions of each standard sample are tested to obtain the interferogram respectively;

Step 3-4, calculate the average wave difference value within a predetermined wave number range

Step 3-5, the thickness d of the oxide ceramic layer and the average wave difference value

Substitute into the following formulas for fitting respectively, and obtain the values of the constants a and b:

The average wave difference

Taking each adjacent trough within the predetermined wave number range as a period, subtracting the wave values corresponding to the troughs at both ends of the predetermined wave number range to obtain a difference, and then dividing the difference by the period within the predetermined wave number range The quantity is the average wave difference value ˉX within the predetermined wave number range. The predetermined wavenumber range is a continuous wavenumber range selected within the wavenumber range of 2100cm ⁻¹ to 1000cm ⁻¹ in the interferogram.

The oxide ceramic layer thickness d of the standard test sample is measured by a scanning electron microscope. According to the average wave difference and the known thickness of each sample, the calculation formula of thickness d and average wave difference is fitted, and the values of constants a and b are respectively: a=2500~3000; b=-1.08~-1.05.

The thickness measurement system and method are also applicable to the measurement of the thickness of the oxide layer on the surface of other alloys, without calculating the refractive index n of the oxide layer to be measured. Through the above-mentioned thickness measurement system and thickness measurement method, the oxide layer on the surface of the sample with different thickness and shape is measured. The results show that the system and method have high accuracy, and the maximum thickness error does not exceed 0.2 microns.

Please refer to FIG. 3 , which is a flow chart of a specific embodiment of the thickness measurement method using the above-mentioned metal oxide ceramic layer thickness measurement system 101, which specifically includes the following steps:

Step S100, providing at least three standard test samples with known different oxide ceramic layer thicknesses. For example, in this embodiment, three plane standard test samples with known different thicknesses of oxide ceramic layers are provided, and the thicknesses are obtained by observing the cross-sections with a scanning electron microscope. For example, the flat standard sample can be zirconium and zirconium alloys with an oxide ceramic layer, as shown in the left views of Figure 5 to Figure 7, the thickness of the oxide ceramic layer of the flat standard sample is 2.844μm/7.056μm/12.544 μm. Due to the change of oxidation parameters, the thickness range of the oxide ceramic layer is basically fixed between 2.5 μm and 12.6 μm during the oxidation process of various test samples prepared, so three standard samples with a total thickness of two ends and the middle of the range were selected. conduct. The accuracy rate will increase with the increase of the number of standard test samples. The accuracy rate of the results below three is low, and it is impossible to draw the law of the infrared interferogram changing with the thickness.

In step S200, the infrared light emitted by the infrared light source 1 passes through the interferometer 2 to generate interference to form interference light. The infrared light source 1 is used to provide infrared light. According to the thickness range of the metal oxide ceramic layer to be measured, the selected infrared wavelength range is from 2.5 μm to 25 μm, and the wave number range is from 4000 cm ⁻¹ to 650 cm ⁻¹ . The interferometer 2 includes a beam splitter, a moving mirror and a fixed mirror, the beam splitter is used to divide the infrared light into two beams, one of which reaches the moving mirror through transmission, and the other reaches the fixed mirror through reflection, The two beams of infrared light respectively pass through the moving mirror and the fixed mirror and then return to the beam splitter. The moving mirror moves linearly at a constant speed, so the two beams of infrared light returning to the beam splitter form a beam splitter. The path difference generates interference to form interference light, and the interference light is used to irradiate the sample.

Step S300, shoot the formed interference light to the correction sheet, use the detector 6 to collect the reflected light reflected from the measured position of the correction sheet, and transmit the reflected light signal to the data processor 7, and the data processor 7 draws Interferogram as background. Specifically, the correction sheet may be an aluminum sheet with better flatness. Because carbon dioxide (CO ₂ ) and water vapor (H ₂ O) in the air also have strong absorption in the infrared spectrum, and it is not easy to subtract, background scanning is also conducive to subtracting the infrared signals of carbon dioxide and water vapor in the air. It is beneficial to obtain a "clean" infrared spectrum of the sample. The aluminum sheet is a flat mirror surface. This material has good reflection performance for infrared light, but it is not the only choice.

Step S400, shoot the formed interference light onto a standard sample of known thickness (the thickness here refers to the thickness of the oxide ceramic layer), and use the detector 6 to collect the reflected light from the measured position of the standard sample. the reflected light, and the reflected light signal is transmitted to the data processor 7, and the data processor 7 outputs the interferogram at the measured position of the standard sample (the horizontal axis is the wave number-the vertical axis is the reflectivity) as shown in Figure 5 to It is shown in the right view of Figure 7. In this way, multiple positions of each standard sample are tested to obtain interferograms respectively. In this step, the position of the test sample can be adjusted according to the position of the light source of the microscope 3, and the interferograms (also called infrared spectrograms) at the center of the planar standard test sample and other four random positions can be obtained respectively.

Specifically, the formed interference light is irradiated on a standard sample of known thickness, specifically including:

Step S410 , placing a standard sample of known thickness on the stage of the microscope 3 . For example, the standard sample can be placed on the stage of the microscope 3 through the adjustment fixture 4 .

In step S420, the interference light enters the microscope 3, and the light source of the microscope 3 shares the same optical path with the interference light.

Step S430, adjust the position of the light source of the microscope 3 to focus on the surface of the standard sample, and the interference light is focused on the surface of the standard sample, so that the detection position can be more clearly confirmed and imaging is more convenient. Focusing on the surface of the sample to be tested by adjusting the position of the light source of the microscope 3 actually focuses the interference light on the surface of the sample, and refraction and reflection occur on the surface of the oxide ceramic layer of the sample.

As shown in Figure 4, after the interference pattern (wavenumber-reflectivity) of the oxide ceramic layer of the test sample corresponds to the actual thickness value, according to the principle formula of reflection and refraction of interference light, the incident beam I ₀ is shot from the air to the oxide ceramic layer surface, the optical path difference between reflected beams _R1 and _R2 is:

When m=-1/2, 1, 3/2, 2, . . . the extremum of interference occurs. n ₁ is the refractive index of the oxide ceramic layer, and n ₂ is the refractive index of the zirconium-niobium alloy. According to the size of n ₁ and n ₂ , it can be divided into two situations: 1. n ₁ > n ₂ , m takes 1/2 and When it is an odd multiple, it corresponds to the maximum value of interference; when m takes an integer value, it corresponds to the minimum value of interference; 2. When n ₁ <n ₂ , the situation is opposite. Use λ _m to represent the wavelength corresponding to the mth extremum, x to represent a positive integer, λ _m+x to represent the wavelength corresponding to the m+x extremum,

Indicates the angle of refraction after the incident light source,

Indicates the incident angle of the infrared light source 1. available:

According to the law of refraction:

So by derivation:

Because λ in the formula is the wavelength, and the unit is m. However, in the interference diagram of infrared light, the abscissa is the wave number and the unit is cm ^-1 . It is known that the wave number is the reciprocal of the wavelength, so the wave number corresponding to another wavelength λ _m is ν _m , and x represents a positive integer, which can be obtained:

At this time, the unit of d is m, which can be converted into μm:

Since the refractive index of the zirconium-niobium alloy matrix is obviously greater than that of the oxide ceramic layer on the surface, it can be known from the second case that the average wave difference in the thickness of the oxide layer d (μm)

(

That is, the wave number difference corresponding to adjacent troughs is the wave difference, and the average value of the wave difference within a section of wave number is the average wave difference) in an inversely proportional function relationship. That is, the oxide layer thickness d (μm) and the average wave difference

satisfy the following formula:

Among them, a and b are constants.

The conventional optical path difference thickness measurement method needs to know the value of the refractive index n, and the oxide layer on the surface of the zirconium-niobium alloy itself is ceramic-like, not pure zirconia, and the ratio of zirconia to oxyzirconia is not a fixed value. For example, from the outermost layer to the junction with the metal substrate, the content of oxygen and zirconium changes in a gradient. Another example is that after the structure of the zirconium-niobium alloy changes, the structure of the impure zirconia formed on the surface will also change, so the n value should change within a certain range. In addition, some traditional test methods also take into account complex factors such as phase shift in the infrared spectrum. This method ignores all these factors.

In the derivation of the formula in this embodiment, although in the initial formula, the default n value remains unchanged, a constant term appears in the formula, and then the measured data is fitted with the average wave difference in the fixed band, which is a part of the real data. One-to-one correspondence, the fitting formula is obtained, which actually covers the influence of the change of n value on the thickness result. The accuracy of the fitting results is sufficient to meet the needs of thickness measurement.

Step S500, fixing the characteristic wave band, and calculating the average wave difference within the range of 2100cm ^-1 to 1000cm ^-1 based on the trough. This wave number range is selected based on the waveform characteristics of each wave number segment. First, the waveform at this position is relatively clear, and it is easier to read the value of the trough. The second is that many other positions have also been tried, and the accuracy is the highest within this range. Specifically, the mean wave difference

The calculation method is: take each adjacent trough in the range of 2100cm ^-1 to 1000cm ^-1 as a period, and subtract the wave values corresponding to the troughs at both ends of the range from 2100cm ^-1 to 1000cm ^-1 to obtain the difference, and then use the difference Divided by the number of cycles in the range from 2100cm ^-1 to 1000cm ^-1 , it is the average wave difference value in the range from 2100cm ^-1 to 1000cm ^-1 . In other embodiments, a smaller continuous range from 2100 cm ⁻¹ to 1000 cm ⁻¹ may also be selected.

As shown in Table 1 below, the average wave difference of each position of the three plane standard samples in the range of 2100cm ^-1 to 1000cm ^-1 :

Table 1 The average wave difference of each sample at each test position

Step S600, according to the average wave difference and the known thickness of each sample, fitting the calculation formula of the thickness d and the average wave difference to obtain the values of the constants a and b respectively: a=2500～3000; b=-1.08～-1.05 . In this embodiment, the formula for calculating the thickness d of the oxide ceramic layer obtained by fitting the data in Table 1 is as follows:

The thickness unit of the oxide ceramic layer d is μm,

Indicates the average wave difference value in the range of 2100cm ^-1 to 1000cm ^-1 in the interferogram of the measured position.

When the selected predetermined wave number range is different, the values of the constants a and b will change slightly. The following are the values of the three groups of a and b measured, and the same average wave difference calculated according to the three calculation formulas Oxide ceramic layer thickness d. However, in this embodiment, the first group of data is used for calculation.

Table 2 Numerical values of a and b and calculation results of oxide ceramic layer thickness d

Specifically, the incident angle of the interfering light

The angle is 45 degrees, so according to the thickness of the plane standard sample and the corresponding average wave difference number, the inverse proportional relationship function fitting can be obtained, and the calculation formula for the thickness d of the oxide ceramic layer mentioned above can be obtained. This formula does not need to be re-fitted every time, after fitting according to the data obtained by the three plane standard samples in step S100, it can represent the oxide ceramic layer (for example, zirconia ZrO ₂ ), and subsequent thickness measurement , this formula can be used directly. The accuracy of the formula will be improved due to the increase of the number of samples in step S100.

Please refer to Fig. 8 to Fig. 12, select a plane test sample with a certain thickness of oxide ceramic layer on the surface, and obtain the interferogram of the center of each plane test sample and other four random positions, a total of 5 positions After (wave number-reflectivity) (as shown in the right side view of Figure 8 to Figure 12), the average wave difference corresponding to each position is obtained, and substituted into the calculation formula of the oxide ceramic layer thickness d in step S600, the surface oxide ceramic can be obtained The measured thickness of the layer. In order to verify the accuracy of the method, the scanning electron microscope 3 was used to measure the thickness of the oxide ceramic layer of the planar test sample, as shown in the left view of Fig. 8-12. The calculation error, statistical data and results are shown in Table 2.

Table 3 Calculation error table of oxide ceramic layer thickness

The measurement results of conventional test methods will be different due to the location of the extreme value selection. This method directly fixes the wavenumber segment, and the reading method is single. At present, whether it is the experimental test results or the verification experimental results, the error is controlled within 0.2 μm, so the accuracy is also very high.

Step S700, direct the formed interference light onto the sample to be tested, the detector 6 is used to collect the reflected light from the measured position of the sample to be tested, and transmit the reflected light signal to the data processor 7, and the data processing The device 7 outputs the interferogram at the measured position of the sample to be tested.

Specifically, directing the formed interference light onto the sample to be tested specifically includes:

Step S710 , placing the sample to be tested on the stage of the microscope 3 . For example, a spherical sample with a ceramic oxide layer of a certain thickness on the surface can be placed on the stage of the microscope 3 by adjusting the jig 5 .

In step S720, the interference light enters the microscope 3, and the light source of the microscope 3 shares the same optical path with the interference light.

Step S730, adjust the position of the light source of the microscope 3 to focus on the surface of the sample to be tested, and the interference light is focused on the surface of the sample to be tested, so that the detection position can be more clearly confirmed and imaging is more convenient. Focusing on the surface of the sample to be tested by adjusting the position of the light source of the microscope 3 actually focuses the interference light on the surface of the sample, and refraction and reflection occur on the surface of the oxide ceramic layer of the sample.

Step S800, calculating the average wave difference value within the range of 2100cm ⁻¹ to 1000cm ⁻¹ and substituting it into the calculation formula of the thickness d of the oxide ceramic layer to complete the measurement of the thickness of the oxide ceramic layer of the sample to be tested. For example, after obtaining the wave number-reflectance diagrams of the center of the spherical sample and four other random positions, a total of 5 positions (as shown in the right view of Figure 13-Figure 17), the average wave difference corresponding to each position is obtained , which is substituted into the calculation formula for the thickness d of the oxide ceramic layer, the measured thickness of the surface oxide ceramic layer can be obtained. In order to verify the accuracy of this method, the thickness of the oxide ceramic layer of the spherical sample was measured using a scanning electron microscope 3 as shown in the left view of Figures 13-17. The calculation error, statistical data and results are shown in Table 3.

Table 4 Calculation error table of oxide ceramic layer thickness

The thickness measurement system and method are also applicable to the measurement of the thickness of the oxide layer on the surface of other alloys, without calculating the refractive index n of the oxide layer to be measured. It is easy to understand that this thickness measurement system and method are also applicable to other qualified thin layers, for example: the thin layer can allow infrared rays to pass through, and the infrared rays will be reflected at the air/thin layer interface and thin layer/base layer interface, And the refractive index of infrared rays in the thin layer and the base layer is not equal. Through the above-mentioned thickness measurement system and thickness measurement method, the oxide layer on the surface of samples with different thicknesses and shapes is measured. The results show that this system and method have high accuracy, and the maximum thickness error does not exceed 0.2 microns.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and thus should not be construed as limiting the application.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In this application, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense, for example, it can be a fixed connection or a detachable connection, unless otherwise clearly specified and limited. , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

In the present application, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may mean that the first and second features are in direct contact, or that the first and second features are indirect through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions are for the purpose of illustration only and are not intended to represent the only embodiment.

Claims

A metal oxide ceramic layer thickness measurement system, wherein the metal oxide ceramic layer thickness measurement system includes:

an infrared light source for providing infrared light;

an interferometer, configured to interfere the infrared light to form interference light, and direct the interference light to the test sample;

a detector for collecting reflected light reflected from said test sample; and

The data processor is used to receive the reflected light signal transmitted by the detector, and output the interferogram at the measured position to obtain the thickness of the metal oxide ceramic layer.
The metal oxide ceramic layer thickness measurement system according to claim 1, further comprising a microscope, the microscope is used to receive the interference light formed by the interferometer, and direct the interference light to the sample .
The metal oxide ceramic layer thickness measurement system according to claim 2, wherein the microscope includes a stage and a light source, the stage is used to carry the sample, and the position of the light source can be adjusted to The surface to be measured of the sample is focused, and the light path of the light source is used to share with the interference light.
The metal oxide ceramic layer thickness measurement system according to claim 3, further comprising an adjustment fixture, the adjustment fixture is arranged on the object stage, the adjustment fixture is used to clamp the sample to be tested, and the adjustment The clamp includes a clamping part and an adjusting knob, the adjusting knob is screwed on the clamping part, and the inner diameter of the clamping part can be adjusted by the adjusting knob.
A method for measuring the thickness of a metal oxide ceramic layer thickness measuring system, which includes the following steps:

Interfering the infrared light emitted by the infrared light source through the interferometer to form interference light;

The formed interference light is irradiated on the sample to be tested, the reflected light reflected from the measured position of the sample to be tested is collected by a detector, and the reflected light signal is transmitted to a data processor, and the data processor outputs the The interferogram at the measured position of the sample to be tested is obtained to obtain the thickness of the metal oxide ceramic layer.
The thickness measuring method according to claim 5, wherein, according to the shown interferogram, the average wave difference value within a predetermined wave number range is calculated and substituted into the calculation formula of the thickness d of the oxide ceramic layer to obtain the oxide ceramic of the sample to be tested The thickness d of the layer, the calculation formula of the thickness d of the oxide ceramic layer is as follows:

in,
Indicates the average wave difference value within the predetermined wavenumber range in the interferogram at the measured position of the sample to be tested; a and b are constants measured in advance by the standard sample.
The method for measuring thickness according to claim 6, wherein the measuring methods of constants a and b are as follows:

Provide at least three standard test samples, the thickness d of the oxide ceramic layer of the at least three standard test samples is different, and the thickness d of the oxide ceramic layer is known;

Interfering the infrared light emitted by the infrared light source through the interferometer to form interference light;

The formed interference light is irradiated to the standard test sample, the reflected light reflected from the measured position of the standard test sample is collected by a detector, and the reflected light signal is transmitted to the data processor, the The data processor outputs the interferogram at the measured position of the standard sample, so that multiple positions of each standard sample are tested to obtain the interferogram respectively;

Calculates the average wave difference over a predetermined wave number range

The oxide ceramic layer thickness d and the average wave difference
Substitute into the following formulas for fitting to obtain the values of constants a and b:
The thickness measuring method according to claim 6, wherein the predetermined wavenumber range is a continuous wavenumber range selected within the wavenumber range of 2100cm −1 to 1000cm −1 in the interferogram.
The thickness measuring method according to claim 6, wherein the values of the constants a and b are respectively: a=2500-3000, b=-1.08--1.05.
The thickness measuring method according to claim 7, wherein the thickness d of the oxide ceramic layer of the standard test sample is measured by a scanning electron microscope.
The thickness measuring method according to claim 6, wherein the average wave difference value
The calculation method is: taking each adjacent trough in the predetermined wave number range as a cycle, subtracting the wave values corresponding to the troughs at both ends of the predetermined wave number range to obtain a difference, and then dividing the difference by the predetermined wave number The number of cycles within the range, which is the average wave difference value within the predetermined wave number range
The thickness measuring method according to claim 6, wherein the wavelength range of the infrared light is 2.5 μm to 25 μm, and the wavenumber range is 4000 cm −1 to 650 cm −1 .
The thickness measuring method according to claim 5, wherein, before the formed interference light is irradiated to the sample to be tested, it also includes:

The formed interference light is sent to a correction sheet, the reflected light reflected from the measured position of the correction sheet is collected by a detector, and the reflected light signal is transmitted to a data processor, and the interference drawn by the data processor is illustration as a background.
The thickness measuring method according to claim 13, wherein the correction sheet comprises an aluminum sheet.
The thickness measuring method according to claim 5, wherein directing the formed interference light to the sample to be tested specifically comprises:

placing the sample to be tested on the stage of the microscope;

Let the interference light enter the microscope, and the light source of the microscope shares the same optical path with the interference light;

Adjusting the position of the light source of the microscope to focus on the surface of the sample to be tested, so that the interference light is focused on the surface of the sample to be tested, and refracted and reflected on the surface.