Method for measuring parameters of thin and brittle ceramic coating

Abstract

The invention discloses a method for measuring parameters of a thin and brittle ceramic coating, and relates to the technical field of material engineering experiments, and the method comprises the following steps: carrying out process deposition on a plate-shaped sample to obtain the thin and brittle ceramic coating, processing the thin and brittle ceramic coating into a sample meeting the in-situ tensile size requirement, recording the initial microstructure and morphology state in an in-situ observation device, and determining the parameters of the thin and brittle ceramic coating according to the initial microstructure and morphology state. Starting microscopic morphology recording and data acquisition of the microscopic equipment to obtain a force-displacement curve of the laminated sample in the stretching process; and collecting the cross-sectional area and the initial length of the sample in the stretching direction, converting the force-displacement data curve into a stress-strain curve by using the cross-sectional area and the initial length, and obtaining the ultimate strength and the tensile modulus of the laminated sample according to the peak value and the slope of the stress-strain curve. Microscale mechanical behavior observation is synchronously carried out in the tensile test process of the laminated material with the ceramic coating, so that material damage behaviors such as crack propagation and the like are researched, and compared with a traditional mechanical test method, the method has higher accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material engineering experiments, in particular to a method for measuring parameters of a thin brittle ceramic coating. BACKGROUND

[0002] As high-performance surface engineering materials, ceramic coatings have characteristics such as corrosion resistance, high hardness, and high temperature resistance, and have good protective effect and irreplaceability in many extreme engineering service environments. They are widely used in thermal barrier coatings, oxidation-resistant sealing coatings in the aerospace field, radiation-resistant coatings, and thermal corrosion-resistant coatings in the energy equipment field, and dielectric layers of semiconductor chips. Optimizing the design of ceramic coatings in extreme service environments is essential for ensuring safety and reliability, increasing service life, and controlling manufacturing costs in various engineering application fields, and this is closely related to mechanical properties such as strength and modulus. Therefore, accurate mechanical parameter measurement of thin brittle ceramic coating materials has certain engineering economic value.

[0003] Traditional mechanical property testing methods mainly target bulk ceramic materials. For basic performance parameters such as tensile strength and tensile modulus, methods such as macroscopic tensile test or in-situ tensile test are mainly used.

[0004] The process adopted by the prior art has the following defects: macroscopic tensile test is only applicable to bulk ceramic materials for sample design and parameter measurement, and cannot be directly applied to ceramic coatings with a thickness much lower than bulk materials. At the same time, the spatial resolution of macroscopic tensile test is large, and it is difficult to capture the micro-zone deformation of ceramic coatings and measure the data, which affects the accuracy of experimental data. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a method for measuring parameters of a thin brittle ceramic coating.

[0006] The present application specifically provides the following technical solution: a method for measuring parameters of a thin brittle ceramic coating, comprising: Depositing a plate-shaped sample made of a skeleton material to obtain a thin brittle ceramic coating; Processing the skeleton plate with the deposited ceramic coating into a sample that meets the size requirements of in-situ tensile test; Installing the sample with a specific shape and size obtained by processing on a micro-tensile stage, recording the initial microstructure and topography state in the in-situ observation equipment, setting the loading mode and loading rate, and then starting the micro-topography recording and data collection of the microscopic equipment to obtain the force-displacement curve during the tensile process of the laminated sample; The cross-sectional area and initial length of the tensile direction of the sample are collected, the cross-sectional area and initial length are used to convert the force-displacement data curve into stress-strain curve, and the strength limit and tensile modulus of the laminated sample are obtained according to the peak value and slope of the stress-strain curve.

[0007] Preferably, the plate-shaped sample made of the skeleton material is subjected to process deposition to obtain a thin brittle ceramic coating, specifically: The plate-shaped sample made of the skeleton material is placed in a space with uniform temperature and atmospheric pressure; The reactant gas is introduced into the space, a chemical reaction occurs at each surface of the plate-shaped sample, and deposition is carried out, the byproduct gas diffuses outward to escape, the brittle ceramic coating is deposited on the surface of the skeleton material, and the whole skeleton material-ceramic coating is processed to obtain a thin brittle ceramic coating.

[0008] Preferably, the skeleton plate with deposited ceramic coating is processed into a sample meeting the in-situ tensile size requirements, specifically: The processed sample is composed of three layers of materials, i.e., the laminated sample with the upper ceramic coating, the middle skeleton material, and the lower ceramic coating in the thickness direction.

[0009] Preferably, the hardness of the skeleton material is higher than that of the measured ceramic coating, and the tensile strength of the skeleton material is higher than that of the measured ceramic coating.

[0010] Preferably, after the skeleton plate with deposited ceramic coating is processed into a sample meeting the in-situ tensile size requirements, it further includes: The connection between the gauge section and the clamping section is polished into a circular arc curve.

[0011] Preferably, after setting the loading mode and loading rate, the microstructure and morphology state are recorded in the in-situ observation equipment, the micro-morphology recording and data collection of the microscopic equipment are started, and the force-displacement curve in the tensile process of the laminated sample is obtained, specifically: The thickness of the skeleton material in the laminated sample is measured by the in-situ observation equipment in the direction perpendicular to the thickness direction of the tensile sample , and the thickness of the upper and lower ceramic coatings , ; The length and width of the gauge section of the laminated sample are measured by observation and recording in the direction parallel to the thickness direction; After recording, the in-situ tensile experiment is started, and the force-displacement data and in the tensile process are recorded to generate the force-displacement curve in the tensile process of the laminated sample.

[0012] Preferably, the step of converting the force-displacement data curve into a stress-strain curve using the cross-sectional area and initial length, and obtaining the ultimate tensile strength and tensile modulus of the laminated specimen based on the peak value and slope of the stress-strain curve, specifically involves: The obtained force-displacement curve is converted into a stress-strain curve, with the specific expression as follows: ; ; in, For stress, In response to the situation; Based on the obtained stress-strain data, the slope of the linear elastic segment of the stress-strain curve is calculated and used as the composite tensile modulus of the laminated specimen. Given the tensile modulus of the skeleton material Solving for the tensile modulus of ceramic materials under the given conditions The specific expression is: .

[0013] Preferably, when mounting the processed specimen of a specific shape and size onto the micro tensile stage, a fixture specifically designed for tensile testing of brittle materials is used.

[0014] Compared with the prior art, the present invention has the following significant advantages: This invention obtains a thin, brittle ceramic coating by depositing a process on a plate-shaped sample, and then processes it into a sample that meets the in-situ tensile dimensional requirements. The initial microstructure and morphology are recorded in an in-situ observation device. After setting the loading mode and loading rate, the microscopic morphology recording and data acquisition of the microscopic device are activated to obtain the force-displacement curve of the laminated sample during the tensile process. This allows for simultaneous observation of microscopic mechanical behavior during the tensile testing of laminated materials with ceramic coatings, and further study of material damage behaviors such as crack propagation. The data post-processing method used can distribute the overall modulus of the laminated sample to the individual layers according to the thickness of each layer. The layer thickness is precisely measured at the microscopic scale by the in-situ observation device, thus providing higher accuracy than traditional mechanical testing methods. Furthermore, since the size of the in-situ tensile sample is only on the millimeter scale, the amount of material consumed in determining the modulus and strength of the thin, brittle ceramic coating is very small, which allows for good measurement of the micro-deformation of the ceramic coating and further improves the accuracy of experimental data. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a plate-shaped skeleton material sample used in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the ceramic coating deposition steps in a specific embodiment of the present invention; Figure 3 is a schematic diagram of a processed laminated sample of a specific embodiment of the present application; Figure 4 is a cross-sectional enlarged view of a laminated sample of a specific embodiment of the present application; Figure 5 is a schematic diagram of an in-situ tensile test of a specific embodiment of the present application; Figure 6 is a flow chart of a method for measuring parameters of a thin and brittle ceramic coating provided by the present application.

[0016] The technical features denoted by the reference numerals in the drawings are as follows: 1, skeleton material; 2, reaction gas; 3, by-product gas; 4, deposition furnace; 5, heating device; 6, upper surface ceramic coating; 7, lower surface coating; 8, in-situ tensile test fixture. DETAILED DESCRIPTION

[0017] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0018] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0019] The ceramic coating commonly used in the prior art is generally a brittle material and has poor shear resistance. When it is processed into a tensile sample and installed in a test device, cracks or even damage can easily occur in the sample due to uneven stress or improper operation. How to accurately measure the mechanical property parameters of the ceramic coating material while observing the microscale scale of the mechanical behavior of the ceramic coating, and ensuring that the sample will not be damaged due to thin thickness and brittleness during the processing and installation process, has become a technical problem to be solved.

[0020] This invention provides a method for determining the strength and modulus of thin, brittle ceramic coatings using in-situ tensile testing. The method includes five steps: selection of the framework material, ceramic coating deposition, laminated specimen preparation, in-situ tensile testing, and data post-processing. After depositing a ceramic coating onto the surface of a high-strength framework material using chemical vapor deposition (CVD) to form a laminated material, it is processed into a specimen suitable for in-situ tensile testing, ensuring that the thin, brittle coating does not fail prematurely due to non-experimental factors. During the in-situ tensile test, the microstructure of the ceramic coating and force-displacement data can be simultaneously characterized and recorded. After data processing, the tensile strength and tensile modulus of the thin, brittle ceramic coating can be obtained. This invention solves the problems that macroscopic mechanical experiments cannot determine the mechanical parameters and observe the microstructure of thin, brittle ceramic coatings, and that single-layer thin, brittle ceramics are prone to non-experimental failure during specimen preparation and in-situ tensile testing.

[0021] like Figure 2 As shown, Figure 1 The skeleton material 1, which is made into a plate-shaped sample, is placed in the deposition furnace 4. The reaction gas 2 introduced into the gas inlet will react and deposit a ceramic coating on the surface of the skeleton material 1 in a uniform high-temperature environment provided by the heating device 5. The gaseous byproducts 3 generated by the reaction are discharged through the gas outlet.

[0022] like Figure 3 As shown, the plate-shaped skeleton material 1 after the ceramic coating is deposited is taken out. At this time, it has become a sample with ceramic coating / skeleton material / ceramic coating. Then the sample is processed into the sample size and shape required for the in-situ tensile test.

[0023] like Figure 4 As shown, the final in-situ tensile specimen is a laminated structure with an upper surface ceramic coating 6, a lower surface ceramic coating 7, and an intermediate skeleton material 1.

[0024] like Figure 5 As shown, a clamp 8, specially designed for tensile testing of brittle materials, is installed on the clamping section of the in-situ tensile specimen, and the entire clamp is installed into the loading device for in-situ tensile testing. Simultaneously, the in-situ observation device is started to perform microscopic characterization and data recording.

[0025] Specifically, such as Figure 6 As shown, the present invention provides a method for determining the parameters of a thin, brittle ceramic coating, comprising the following steps: Step S1: Perform process deposition on the plate-shaped sample made of skeleton material to obtain a thin and brittle ceramic coating.

[0026] The skeleton material is selected to determine the material to be deposited on its surface to form a ceramic coating. In subsequent sample processing and in-situ tensile experiments, the skeleton material mainly serves to fix the thin and brittle ceramic coating, preventing the coating from being damaged or directly destroyed due to its thin and brittle characteristics, and ensuring the accuracy of the data measured in the coating strength and modulus experiments.

[0027] The skeleton material should be able to enhance the ceramic coating attached thereto to ensure that it does not prematurely break due to its thinness during sample processing and in-situ tensile experiments. Therefore, the skeleton material generally needs to have a higher hardness than the ceramic coating being measured to achieve the requirement of enhancing the stability of the coating during the experiment. At the same time, the skeleton material also needs to have a higher tensile strength and a lower tensile modulus than the ceramic coating being measured, otherwise it will crack before the coating material during the in-situ tensile experiment, and when the crack propagates into the ceramic coating, the coating will be damaged prematurely due to the shear stress, ultimately affecting the accuracy of the experimental data. After the skeleton material is selected, it is generally made into a plate-shaped sample to deposit the ceramic coating on its surface and to perform subsequent sample processing.

[0028] The ceramic coating deposition is the deposition of a thin and brittle ceramic coating on the skeleton material made into a plate-shaped sample using the chemical vapor deposition (CVD) process. The plate made of the skeleton material is placed in a space with uniform temperature and atmospheric pressure, and the reactant gas is introduced to react and deposit on the surface of the plate-shaped sample in all directions. The byproduct gas 3 diffuses outward and escapes, and finally a brittle ceramic coating is deposited on the surface of the skeleton material. Since the ceramic coating is deposited and grown on the surface of the skeleton material, it has good adhesion with the skeleton material which has higher strength, and the sample processing can be performed as a whole with the skeleton material and the ceramic coating, without damage and destruction due to the thinness and brittleness of the coating.

[0029] Step S2: Process the skeleton plate with the deposited ceramic coating into a sample that meets the size requirements of in-situ tensile.

[0030] The laminated sample processing is to process the skeleton plate with the deposited ceramic coating into a sample that meets the size requirements of in-situ tensile. This sample can be stably used for the processing of various special-shaped parts and the measurement of the strength and modulus of thin and brittle coatings, because the ceramic materials on both sides of the skeleton material are tightly combined with the skeleton material in a deposited and grown manner, and are not easily damaged during the processes of online cutting, sample loading for in-situ experiments, and pre-tightening force application, etc. due to their thinness and brittleness. In order to prevent stress concentration, the connection between the gauge length section and the clamping section should be polished into a circular arc curve.

[0031] The in-situ tensile sample obtained after processing the laminated sample should be composed of three layers of materials, i.e. the laminated sample with the structure of ceramic coating on the upper surface, the middle skeleton material and the ceramic coating on the lower surface in the thickness direction, which is caused by the uniform deposition of ceramic coating on the upper and lower surfaces of the skeleton material plate during the CVD process. Although the skeleton material is not an experimental object, the overall modulus of the laminated sample can be obtained by the equivalent modulus formula of the multi-layer material, and the tensile modulus and strength of the ceramic coating can be obtained by introducing the in-situ tensile experimental data for processing.

[0032] Step S3: The sample with specific shape and size obtained after processing is installed on the micro tensile stage, the initial microstructure and morphology state are recorded in the in-situ observation equipment, and after setting the loading mode and loading rate, the micro morphology recording and data acquisition of the microscopic equipment are started, and the force-displacement curve and the evolution image of the micro morphology during the tensile process of the laminated sample are obtained.

[0033] The in-situ tensile experiment is a process of tensile experiment on the laminated sample under the observation of high-resolution in-situ observation equipment such as scanning electron microscope (SEM) using a micro tensile loading device. The sample with specific shape and size obtained after processing is installed on the micro tensile stage, and the corresponding clamp is installed. After the equipment is calibrated, it is put into the in-situ observation equipment, and the initial microstructure and morphology state are recorded. After setting the loading mode and loading rate, the in-situ tensile experiment is started, and the micro morphology recording and data acquisition of the microscopic equipment are started synchronously. Finally, the force-displacement curve and the evolution image of the micro morphology during the tensile process of the laminated sample are obtained after the experiment is finished.

[0034] Before the in-situ tensile experiment starts, the in-situ observation equipment needs to be used to observe and record in the direction perpendicular to the thickness direction of the tensile sample, to measure the thickness of the skeleton material in the laminated sample , and the thickness of the upper and lower ceramic coatings , . Then, the observation and recording are carried out in the direction parallel to the thickness direction, to measure the length and the width of the gauge section of the laminated sample. After recording, the in-situ tensile experiment is started, and the force-displacement data and during the tensile process are recorded, to generate the force-displacement curve during the tensile process of the laminated sample. When the ceramic coating appears crack and brittle fracture, the experiment is stopped. The in-situ observation equipment is used to re-calibrate the crack position and direction, and the length of the gauge section of the sample is recorded again .

[0035] Step S4: collecting the cross-sectional area and initial length of the sample in the tensile direction, converting the force-displacement data curve into a stress-strain curve using the cross-sectional area and initial length, and obtaining the strength limit and tensile modulus of the laminated sample according to the peak value and slope of the stress-strain curve.

[0036] Data post-processing is to convert the force-displacement data curve obtained from the in-situ tensile test into a stress-strain curve according to the cross-sectional area and initial length of the sample in the tensile direction, and to obtain the strength limit and tensile modulus of the laminated sample according to the peak value and slope of the curve.

[0037] In the data post-processing step, the strength limit obtained by tensile test of the laminated sample can be directly used for the strength limit of the ceramic coating. However, since the laminated sample has a structure of ceramic coating / skeleton material / ceramic coating in the thickness direction, the tensile modulus obtained according to the stress-strain curve is the composite modulus of the whole three-layer material, and the true tensile modulus of the ceramic coating needs to be solved according to the thickness of each layer of material and the known modulus of the skeleton material. First, convert the obtained force-displacement curve into a stress-strain curve according to formula (1):

[0038] (1); wherein, is the stress, is the strain.

[0039] According to the obtained stress-strain data, the slope of the linear elastic section of the stress-strain curve is calculated and taken as the composite tensile modulus of the laminated sample . Finally, the tensile modulus of the ceramic material is solved according to formula (2) under the condition that the tensile modulus of the skeleton material is known.

[0040] (2); The method for measuring the strength and modulus of thin brittle ceramic coating by in-situ tensile test according to the present application solves the problem that traditional macroscopic mechanical test cannot be used for microcosmic test and characterization of coating materials, and the thin brittle ceramic coating is easily damaged during the pre-treatment process, affecting the accuracy of the results, and to some extent, saves the economic cost and time cost.

[0041] The above content is a further detailed description of the present application in combination with specific preferred embodiments. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present application.

Claims

1. A method for determining parameters of thin, brittle ceramic coatings, characterized in that, include: A thin, brittle ceramic coating was obtained by process deposition on a plate-shaped sample made of a framework material. The skeleton plate with the ceramic coating is processed into a specimen that meets the requirements of in-situ tensile dimensional analysis. The sample with a specific shape and size obtained by processing is installed on a micro tensile stage. The initial microstructure and morphology are recorded in the in-situ observation device. After setting the loading mode and loading rate, the microscopic morphology recording and data acquisition of the microscopic device are turned on to obtain the force-displacement curve of the laminated sample during the tensile process. The cross-sectional area and initial length of the specimen in the tensile direction are collected. The force-displacement data curve is converted into a stress-strain curve using the cross-sectional area and initial length. The ultimate tensile strength and tensile modulus of the laminated specimen are obtained based on the peak value and slope of the stress-strain curve.

2. The method for determining parameters of a thin, brittle ceramic coating as described in claim 1, characterized in that, The process of depositing a thin, brittle ceramic coating on a plate-shaped sample made of a framework material specifically involves: A plate-shaped specimen made of skeleton material is placed in a space with uniform temperature and atmospheric pressure. Reactant gases are introduced into the space, where chemical reactions occur and deposits occur on the surfaces of the plate-shaped sample. Byproduct gases diffuse outwards, depositing and covering a brittle ceramic coating on the surface of the skeleton material. The sample is then processed as a whole, consisting of the skeleton material and the ceramic coating, to obtain a thin, brittle ceramic coating.

3. The method for determining parameters of a thin, brittle ceramic coating as described in claim 1, characterized in that, The process of machining the skeleton plate with the deposited ceramic coating into a specimen that meets the in-situ tensile dimensional requirements is specifically as follows: The processed specimen consists of three layers of material, namely, a stacked specimen with a thickness structure consisting of an upper surface ceramic coating, a middle skeleton material, and a lower surface ceramic coating.

4. The method for determining parameters of a thin, brittle ceramic coating as described in claim 1, characterized in that, The hardness of the skeleton material is higher than that of the measured ceramic coating, and the tensile strength of the skeleton material is higher than that of the measured ceramic coating.

5. The method for determining the parameters of a thin, brittle ceramic coating as described in claim 1, further comprising, after processing the skeleton plate with the deposited ceramic coating into a sample that meets the in-situ tensile dimensional requirements: The connection between the gauge length section and the clamping section is ground into a rounded curve.

6. The method for determining parameters of a thin, brittle ceramic coating as described in claim 1, wherein the initial microstructure and morphology are recorded in the in-situ observation device, and after setting the loading mode and loading rate, the microscopic morphology recording and data acquisition of the microscopic device are activated to obtain the force-displacement curve during the tensile process of the laminated sample, specifically as follows: The thickness of the skeleton material in the laminated specimen was measured by observing and recording data in the direction perpendicular to the thickness of the tensile specimen using in-situ observation equipment. And the thickness of the upper and lower ceramic coatings , ; Observations and records were made parallel to the thickness direction to measure the length of the gauge length of the laminated specimen. and width ; After the initial recording was completed, an in-situ tensile test was conducted, and the force-displacement data during the tensile process were recorded. and Force-displacement curves are generated during the tensile process of the laminated specimen.

7. The method for determining parameters of a thin, brittle ceramic coating as described in claim 6, characterized in that, The process involves converting the force-displacement data curve into a stress-strain curve using the cross-sectional area and initial length, and obtaining the ultimate tensile strength and tensile modulus of the laminated specimen based on the peak value and slope of the stress-strain curve. Specifically: The obtained force-displacement curve is converted into a stress-strain curve, with the specific expression as follows: ； ； in, For stress, In response to the situation; Based on the obtained stress-strain data, the slope of the linear elastic segment of the stress-strain curve is calculated and used as the composite tensile modulus of the laminated specimen. Given the tensile modulus of the skeleton material Solving for the tensile modulus of ceramic materials under the given conditions The specific expression is: 。 8. The method for determining parameters of a thin, brittle ceramic coating as described in claim 1, characterized in that, When mounting the processed specimen of a specific shape and size onto the micro tensile stage, a fixture specifically designed for tensile testing of brittle materials is used.

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