A method for analyzing the maximum temperature experienced by electrothermal alloys based on surface color

Abstract

The present invention provides a method for analyzing the highest temperature experienced by an electrothermal alloy based on surface color. The 0Cr25Al5 electrothermal alloy and its products work in an air atmosphere and a high temperature environment. The surface is oxidized at high temperature to produce an oxide film. The higher the temperature, the faster the oxidation speed, and the thicker the oxide film thickness. The oxide film is extremely thin and dense, and can show interference colors. The color of the interference color is related to the thickness of the oxide film. After the 0Cr25Al5 electrothermal alloy and its products experience high temperature oxidation for a certain period of time, the thickness of the oxide film generated is related to the highest temperature experienced. The visible light reflectivity test using a spectrophotometer can obtain the visible light wavelength with the highest reflectivity. Substituting it into the formula given by the present invention, the highest temperature experienced by the 0Cr25Al5 electrothermal alloy and its products can be calculated. The advantages of the method of the present invention are: no need to prepare for the test in the early stage; no need to observe the 0Cr25Al5 electrothermal alloy and its products when they are working; non-contact type is adopted, and the surface of the test object is not damaged.

Description

Technical Field

[0001] The invention relates to the technical field of testing and analyzing electrothermal alloy materials, and in particular to a method for analyzing the maximum temperature experienced by an electrothermal alloy based on surface color. Background Art

[0002] Iron-chromium-aluminum alloy is one of the most widely used electric heating alloy materials. Its advantages include: large resistivity, small resistance temperature coefficient, good heat resistance, and oxidation resistance at high temperatures. Iron-chromium-aluminum alloy is widely used in industrial production and life. 0Cr25Al5 electric heating alloy is one of the most widely used grades of iron-chromium-aluminum alloy.

[0003] The surface of 0Cr25Al5 electric heating alloy and its products will be oxidized in air atmosphere, and the oxidation rate is related to the ambient temperature and time of the material. With the different temperatures, the surface of 0Cr25Al5 electric heating alloy and its products will be oxidized to different degrees, which is manifested as different oxide film thickness.

[0004] After 0Cr25Al5 electrothermal alloy and its products are exposed to high temperature in air atmosphere, their surface presents a certain color. The reason for this high temperature discoloration is that the surface of the material is oxidized to form an oxide film, and the thickness of the oxide film changes, causing interference color. The surface oxidation color is mainly related to its chemical composition, the highest temperature and time of high temperature oxidation. Therefore, the highest temperature experienced by 0Cr25Al5 electrothermal alloy and its products during working in a high temperature environment can be inferred by analyzing the oxidation color of the surface; currently in engineering, the working temperature experienced by 0Cr25Al5 electrothermal alloy parts can be obtained by thermocouples, infrared temperature measurement, temperature indicating paint and other methods, but the temperature measurement process is relatively complicated, costly, and requires the arrangement of test conditions in advance.

[0005] These methods are not applicable to some parts where it is inconvenient to place thermocouples or temperature-indicating paints or where direct observation is not possible during operation. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for analyzing the maximum temperature experienced by an electrothermal alloy based on its surface color, and to provide a method for analyzing the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products in an air atmosphere.

[0007] The second purpose of the present invention is to provide a method for analyzing the maximum temperature experienced by an electrothermal alloy based on its surface color, which can provide a method for analyzing the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products where it is inconvenient to place thermocouples and temperature-indicating paints and cannot be directly observed during operation.

[0008] The third object of the present invention is to provide a method for analyzing the maximum temperature experienced by an electrothermal alloy based on its surface color, which can analyze the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products through the surface oxidation color.

[0009] The object of the present invention is achieved by a method for analyzing the maximum temperature experienced by an electrothermal alloy based on surface color, characterized by: deriving the relationship between the surface oxidation weight gain value and temperature of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation for a certain period of time at different temperatures; The relationship between the maximum temperature T and Δm / s experienced by 0Cr25Al5 electrothermal alloy and its products is as follows: T=k1(Δm / s) 2 +k2(Δm / s)+k3……(1) Where, T is the highest temperature experienced by 0Cr25Al5 electrothermal alloy and its products; Δm / s is the oxidation weight gain per unit area of ​​0Cr25Al5 electrothermal alloy and its parts; k1, k2, k3 are coefficients; The relationship between the oxidation weight gain per unit area and the oxide film thickness of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation is as follows: Δm / s=ρd……(2) Where, d is the thickness of the oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; ρ is the density of the oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; Substituting (2) into (1) we get: T = k1 (ρd) 2 +k2(ρd)+k3……(3) According to the principle of optical interference, when the oxide film (304) is observed from a vertical direction, the incident angle is zero, the incident light (301) is vertically incident on the surface of the oxide film (304), and the optical path difference between the reflected light (302) and the refracted light (303) reflected by the 0Cr25Al5 electrothermal alloy substrate (305) is 2nd, where n and d are the refractive index and film thickness of the oxide film (304), respectively; When the optical path difference in the oxide film layer is an integer multiple of the wavelength λ of the light wave, interference occurs, that is, the light interference enhancement formula is: iλ=2nd……(4) In the formula, i is an integer, which can be 0, 1, 2, 3, ... Substituting into formula (3), we have: T = k1 [ρiλ / (2n)] 2 +k2[ρiλ / (2n)]+k3……(5) The preferred values ​​of the coefficients in the formula are as follows: k1=-199.1172; k2=588.0964; k3=769.6729; The interference color displayed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation is calculated using formula (5); Use a spectrophotometer to test the visible light reflectance of its surface and record the visible light wavelength value λ with the highest reflectance; By introducing the wavelength value λ into formula (5), the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products can be obtained.

[0010] The advantages of the present invention are: 1. The method disclosed in the present invention uses the 0Cr25Al5 electrothermal alloy and its workpiece surface state that have been subjected to high temperatures to analyze the highest temperature experienced, and does not require test preparation before experiencing high temperatures.

[0011] 2. The method disclosed in the present invention uses the highest temperature experienced by the 0Cr25Al5 electrothermal alloy and its workpiece surface state that have experienced high temperatures. It does not need to be observed when it is working, and has a wide range of applications.

[0012] 3. The method disclosed in the present invention uses the highest temperature experienced by the 0Cr25Al5 electrothermal alloy and its products that have been subjected to high temperatures to analyze the surface state. The analysis process is non-contact and does not damage the surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solution of the embodiment of the present invention or the existing design method, the following briefly introduces the drawings required in the description of the embodiment or the existing design method: Figure 1 It is the oxidation weight gain curve of 0Cr25Al5 electrothermal alloy and its products during oxidation at different temperatures; Figure 2 The maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its parts after high temperature oxidation, corresponding to the mass increase per unit area; Figure 3 This is a schematic diagram of the principle of oxide film interference color; In the figure, 101, the surface weight gain curve of 0Cr25Al5 electrothermal alloy and its products changing with time at 950℃; 102, the surface weight gain curve of 0Cr25Al5 electrothermal alloy and its products changing with time at 1050℃; 103, the surface weight gain curve of 0Cr25Al5 electrothermal alloy and its products changing with time at 1150℃; 201, the surface weight gain value of 0Cr25Al5 electrothermal alloy and its products after high-temperature oxidation after a certain period of time corresponding to the highest heating temperature; 301, incident light; 302, reflected light; 303, refracted light; 304, oxide film; 305, 0Cr25Al5 electrothermal alloy matrix. DETAILED DESCRIPTION

[0014] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so as to fully understand and implement the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0015] Meanwhile, in the following description, many specific details are set forth for the purpose of explanation to provide a thorough understanding of the embodiments of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the specific details or the specific manner described herein. Example 1

[0016] This embodiment discloses a method for analyzing the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products. The principle rule is that the interference color displayed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation, specifically, the visible light wavelength with the highest reflectivity obtained by the visible light reflectivity test is related to the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products. The rule is summarized as follows: according to Figure 1 The surface weight gain curves of 0Cr25Al5 electrothermal alloy and its products at 950°C (101), 1050°C (102), and 1150°C (103) shown in the figure can be used to deduce the relationship between the surface oxidation weight gain value and temperature of 0Cr25Al5 electrothermal alloy and its products after high-temperature oxidation for a certain period of time at different temperatures, and the relationship can be drawn as shown in the figure. Figure 2The surface oxidation weight gain value of 0Cr25Al5 electrothermal alloy and its products after high-temperature oxidation after a certain period of time corresponds to the highest heating temperature curve (201). After a certain period of high-temperature oxidation reaches a stable state, the greater the surface oxidation weight gain value per unit area of ​​0Cr25Al5 electrothermal alloy and its products, the higher the highest temperature it has experienced. The relationship between the highest temperature T and Δm / s experienced by 0Cr25Al5 electrothermal alloy and its products is summarized as follows: T=k1(Δm / s) 2 +k2(Δm / s)+k3……(1) In the formula, T is the highest temperature experienced by 0Cr25Al5 electrothermal alloy and its products; Δm / s is the oxidation weight gain per unit area of ​​0Cr25Al5 electrothermal alloy and its parts; k1, k2, k3 are coefficients; The relationship between the oxidation weight gain per unit area and the oxide film thickness of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation is as follows: Δm / s=ρd……(2) In the formula, d is the thickness of the oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; ρ is the density of oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; Substituting (2) into (1) we get: T = k1 (ρd) 2 +k2(ρd)+k3……(3) The oxide film on the surface of 0Cr25Al5 electrothermal alloy and its products can produce interference effect of visible light. The principle of optical interference is as follows: Figure 3 As shown, when the oxide film 304 is observed from the vertical direction, the incident angle is zero degrees, the incident light 301 is vertically incident on the surface of the oxide film 304, and the optical path difference between the reflected light 302 and the refracted light 303 reflected by the 0Cr25Al5 electrothermal alloy substrate 305 is 2nd, where n and d are the refractive index and film thickness of the oxide film 304, respectively. When the optical path difference in the oxide film layer is an integer multiple of the wavelength λ of the light wave, interference occurs, that is, the optical interference enhancement formula is: iλ=2nd……(4) In the formula, i is an integer, ranging from 0, 1, 2, 3, ... Substituting into formula (3), we have: T = k1 [ρiλ / (2n)] 2 +k2[ρiλ / (2n)]+k3……(5) Formula (5) can be used to relate the interference color displayed on the surface of 0Cr25Al5 electrothermal alloy and its products after high-temperature oxidation, specifically, the visible light wavelength with the highest reflectivity obtained by the visible light reflectivity test, to the highest temperature experienced by 0Cr25Al5 electrothermal alloy and its products.

[0017] When the 0Cr25Al5 electrothermal alloy and its products to be analyzed have been subjected to high-temperature oxidation in air for a certain period of time, the visible light reflectivity of the surface is tested using a spectrometer, and the visible light wavelength value λ with the highest reflectivity is recorded.

[0018] By introducing the wavelength value λ into formula (5), the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products can be obtained.

[0019] The principle of the present invention is: under air atmosphere, a very thin and dense oxide film will be generated on the surface of 0Cr25Al5 electric heating alloy and its products in a high temperature environment. The higher the temperature, the faster the oxidation rate and the thicker the oxide film. Under the condition of unchanged environmental conditions, when the oxide film thickness reaches a certain level, metal elements cannot penetrate this thick oxide film, the oxidation reaction rate tends to stagnate, and the film layer no longer grows thicker. Therefore, after the oxidation process reaches a certain length of time, the thickness of the oxide film on the surface of 0Cr25Al5 electric heating alloy and its products is related to the temperature of the environment in which they are located.

[0020] The oxidation weight gain curve of 0Cr25Al5 electrothermal alloy after oxidation at different temperatures for a certain period of time is as follows Figure 1 As shown in the figure, the oxidation rate of 0Cr25Al5 electrothermal alloy at three temperatures increases with time and reaches a stable state after a certain period of time. The average oxidation rate of 0Cr25Al5 electrothermal alloy increases with increasing temperature.

[0021] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention, as well as applications to fields not mentioned in the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for analyzing the maximum temperature experienced by an electrothermal alloy based on its surface color, characterized by: The relationship between the surface oxidation weight gain and temperature of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation for a certain period of time at different temperatures is derived; The relationship between the maximum temperature T and Δm / s experienced by 0Cr25Al5 electrothermal alloy and its products is as follows: T=k1(Δm / s) 2 +k2(Δm / s)+k3……(1) Where, T is the highest temperature experienced by 0Cr25Al5 electrothermal alloy and its products; Δm / s is the oxidation weight gain per unit area of ​​0Cr25Al5 electrothermal alloy and its parts; k1, k2, k3 are coefficients; The relationship between the oxidation weight gain per unit area and the oxide film thickness of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation is as follows: Δm / s=ρd……(2) Where, d is the thickness of the oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; ρ is the density of the oxide film formed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation; Substituting (2) into (1) we get: T=k1(ρd) 2 +k2(ρd)+k3……(3) According to the principle of optical interference, when the oxide film (304) is observed from a vertical direction, the incident angle is zero degrees, the incident light (301) is vertically incident on the surface of the oxide film (304), and the optical path difference between the reflected light (302) and the refracted light (303) reflected by the 0Cr25Al5 electrothermal alloy substrate (305) is 2nd, where n and d are the refractive index and film thickness of the oxide film (304), respectively; when the optical path difference in the oxide film layer is an integer multiple of the wavelength λ of the light wave, interference occurs, that is, the optical interference enhancement formula is: iλ=2nd……(4) In the formula, i is an integer, which can be 0, 1, 2, 3, ... Substituting into formula (3), we have: <h2 style=";text-align:left;direction:ltr">T=k1[ρiλ / (2n)]<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +k2[ρiλ / (2n)]+k3……(5) The preferred values ​​of the coefficients in the formula are as follows: k1=-199.1172； k2=588.0964； k3=769.6729； The interference color displayed on the surface of 0Cr25Al5 electrothermal alloy and its products after high temperature oxidation is calculated using formula (5); Use a spectrophotometer to test the visible light reflectance of its surface and record the visible light wavelength value λ with the highest reflectance; By introducing the wavelength value λ into formula (5), the maximum temperature experienced by 0Cr25Al5 electrothermal alloy and its products can be obtained.

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