Method for determining multi-factor accelerated aging condition of rubber sealing material

Abstract

The invention relates to a method for determining a multi-factor accelerated aging condition of a rubber sealing material. Comprising the following steps: respectively carrying out single-factor aging test on an unaged rubber sealing material by adopting a plurality of single-factor test conditions, and obtaining a first test parameter group; determining influence factors and levels thereof according to the first test parameter group; combining the influence factor and the level thereof with the test factor and the level thereof to form a multi-factor test condition; the unaged rubber sealing material is experimented under the multi-factor testing condition, and a second testing parameter set is obtained; and determining an accelerated aging condition according to the second test parameter group. According to the method, the typical aging influence factors and the levels thereof are selected according to the result of the single-factor aging test, accurate focusing of the main aging influence factors and the levels thereof is realized, and the result acquisition period of multi-factor accelerated aging can be shortened while the accuracy is ensured.

Description

Technical Field

[0001] The present application relates to the field of sealing performance status detection and evaluation of power equipment, and in particular to a method for determining multi-factor accelerated aging conditions of rubber sealing materials. Background Art

[0002] The failure of sealing materials in power equipment will bring serious safety hazards to the operation of the power grid, so it is extremely important to predict the life of rubber sealing materials. The existing evaluation method for the performance of rubber sealing materials mainly adopts artificial accelerated aging experiments, which are mostly limited to single factors. However, when sealing materials are in actual service, they will face the combined influence of multiple factors such as high temperature, cyclic temperature difference, vibration, and medium corrosion. It is difficult to approach the actual working conditions of sealing materials with only a single factor, resulting in large deviations in life prediction. When conducting multi-factor artificial accelerated aging experiments, due to the complexity of the factors and their levels, the cycle of the aging experiment is greatly extended and the results of the experiment lack reliability. There is no scientific method for confirming multi-factor accelerated aging conditions. Summary of the invention

[0003] Based on this, it is necessary to provide a method for determining multi-factor accelerated aging conditions of rubber sealing materials to improve the setting efficiency of multi-factor accelerated aging conditions and improve the relevance of multi-factor accelerated aging tests.

[0004] The method for determining the multi-factor accelerated aging conditions of rubber sealing materials provided in the present application comprises the following steps:

[0005] Test the initial parameters of unaged rubber sealing materials;

[0006] Using multiple single-factor test conditions to perform single-factor aging tests on unaged rubber sealing materials, respectively, to obtain first test parameter groups corresponding to multiple single-factor aging tests and including first test parameters at multiple aging times;

[0007] Selecting influencing factors and their levels from a plurality of the single-factor test conditions according to the first test parameter group;

[0008] combining at least one of the influencing factors and its level with the test factor and its level to form a multi-factor test condition;

[0009] Performing a multi-factor aging test on an unaged rubber sealing material under the multi-factor test conditions to obtain a second test parameter group including second test parameters under multiple aging times;

[0010] The multi-factor accelerated aging conditions are determined according to the second test parameter group.

[0011] In some embodiments, determining the multi-factor accelerated aging condition according to the second test parameter group includes:

[0012] Characterizing the correlation between the second test parameter and the aging time of the multi-factor aging test using the Pearson correlation coefficient r;

[0013] The multi-factor test condition corresponding to the correlation coefficient r≤0.05 is selected as the accelerated aging condition.

[0014] In some implementations, selecting influencing factors and their levels from the plurality of single-factor test conditions according to the first test parameter group includes:

[0015] Calculating the rate of change of the first test parameter after the single factor aging test relative to the initial parameter of the unaged rubber sealing material;

[0016] The influencing factors and their levels are selected in the single factor test condition according to the change rate.

[0017] In some implementations, selecting the influencing factors and their levels in the single factor test conditions according to the change rate includes:

[0018] The single factor and its level corresponding to the change rate ≥ 10% are selected as the influencing factor and its level.

[0019] In some of the embodiments, at least one of the influencing factors and their levels are combined with the test factors and their levels according to an orthogonal design experimental method or a uniform design experimental method.

[0020] In some embodiments, the first test parameter includes one or more of compression set, tensile strength, tear strength, elongation at break, and water absorption; and / or,

[0021] The second test parameter includes one or more of compression permanent deformation rate, tensile strength, tear strength, elongation at break and water absorption rate.

[0022] In some embodiments, the single factor aging test includes one or more of a hot air aging test, a constant humidity and heat aging test, a low temperature aging test, an ultraviolet aging test, an acid salt spray test, and a swept frequency vibration test.

[0023] In some embodiments, the test factors and their levels include one or more of stress factors and their levels and medium factors and their levels.

[0024] In some embodiments, the stress factors and their levels include: one or more of compression force 2000N, compression force 3000N, compression force 4000N, 20% compression rate, 25% compression rate, and 30% compression rate.

[0025] In some embodiments, the medium factors and their levels include one or both of oil medium and water medium.

[0026] In the method for determining the multi-factor accelerated aging conditions of rubber sealing materials of the present application, by first conducting a single-factor aging test and then selecting typical aging influencing factors and their levels based on the results of the single-factor aging test, a precise focus on the main aging influencing factors and their levels is achieved, which effectively narrows the selection range of factors and their levels of the multi-factor test, and can shorten the result acquisition cycle of multi-factor accelerated aging while ensuring accuracy. In addition, the method for determining the multi-factor accelerated aging conditions of the present application takes into account the conditions of multiple main aging influencing factors, which is conducive to a more scientific analysis of the aging performance of rubber sealing materials under comprehensive environmental conditions, and improves the reliability of the prediction of the actual service life of rubber sealing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0028] Figure 1 The present invention is a flowchart of a method for determining multi-factor accelerated aging conditions of a rubber sealing material in one embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0030] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In this application, "at least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0033] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0034] In this application, "above" or "below" includes the number itself. For example, "1 below" includes 1.

[0035] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0036] With the development of the power industry, the coverage of power equipment and the precision of equipment are getting higher and higher. Since the working environment of power equipment is relatively complex, the sealing material must not only have good sealing performance, but also have water resistance, moisture resistance, sealing medium resistance, high and low temperature resistance and other properties to cope with different working environments. Rubber sealing materials are prepared into various seals and widely used in power equipment because of their good elasticity, long service life, low cost, corrosion resistance, simple manufacturing process, and convenient replacement. At present, the common sealing materials in various types of power equipment include nitrile rubber, fluororubber, fluorosilicone rubber and EPDM rubber. However, there are also many problems in the use of rubber sealing materials. As a polymer material, the performance of rubber sealing materials deteriorates due to aging during use, and the resulting poor sealing problem is more serious. Therefore, it is necessary to study the aging performance of rubber sealing materials.

[0037] When conducting aging tests on rubber materials, in order to pursue consistency between test results and actual applications, natural aging test methods were often used in the early days. However, natural aging has the disadvantages of long test cycles, difficult to control environmental variables, and difficulty in separating and studying various influencing factors. In addition, due to the large differences in environmental conditions in different regions, natural aging can only be studied in one specific environment, and the test efficiency is low. Therefore, artificial accelerated aging test methods with short test cycles and controllable test variables have gradually replaced natural aging test methods.

[0038] According to different aging environments, researchers have designed aging boxes that can create different aging environments to age sealing materials. The aging box can be used to perform aging tests such as heat accelerated aging, wet heat aging, ultraviolet accelerated aging, artificial corrosion aging, and salt spray aging on rubber. By conducting artificial accelerated aging experiments on rubber materials, the life information of the rubber can be obtained in a shorter time, and it can assist in judging whether the rubber needs to be retired. However, the existing evaluation methods for rubber sealing performance are mostly limited to single-factor artificial accelerated aging tests. The acceleration conditions of single factors are quite different from the actual service scenarios of rubber sealing materials, resulting in distorted results of the life prediction of rubber sealing materials. However, due to the complex combination of multiple factors and their levels, if the conditions of multiple factors are combined at will, the cycle of the accelerated experiment will be greatly extended, and effective life information of rubber sealing materials cannot be quickly obtained. At present, there is no scientific method for determining the acceleration conditions of multi-factor artificial accelerated aging experiments.

[0039] In view of the shortcomings of the existing methods, the present invention proposes a method for determining the multi-factor accelerated aging conditions of rubber sealing materials for power equipment. The specific implementation methods of the present application will be described in detail below.

[0040] See also Figure 1 . Figure 1 The present invention is a flowchart of a method for determining multi-factor accelerated aging conditions of a rubber sealing material in one embodiment of the present application.

[0041] The method for determining the multi-factor accelerated aging conditions of rubber sealing materials includes the following steps:

[0042] Test the initial parameters of unaged rubber sealing materials;

[0043] Single factor aging tests are performed on unaged rubber sealing materials using multiple single factor testing conditions to obtain first test parameter groups corresponding to the multiple single factor aging tests and including first test parameters at multiple aging times.

[0044] Influencing factors and their levels are selected from a plurality of single-factor test conditions according to the first test parameter group; at least one influencing factor and its level are combined with a test factor and its level to form a multi-factor test condition.

[0045] A multi-factor aging test is performed on an unaged rubber sealing material under multi-factor test conditions to obtain a second test parameter group including second test parameters under multiple aging times; and accelerated aging conditions are determined based on the second test parameter group.

[0046] In some embodiments, the method of determining the accelerated aging condition according to the second test parameter set includes:

[0047] The Pearson correlation coefficient r was used to characterize the correlation between the second test parameter and the aging time of the multi-factor aging test, and the multi-factor test conditions corresponding to the correlation coefficient r≤0.05 were selected as the accelerated aging conditions.

[0048] The correlation coefficient r can reflect the correlation between two variables. Generally speaking, when the correlation coefficient r≤0.05, the correlation between the two variables is significant.

[0049] The calculation formula of Pearson's correlation coefficient r is as follows:

[0050]

[0051] Where, t i is the aging time, is the average aging time of this group of data, x i is the aging time t i The second test parameter when is the average value of the second test parameter of this group of data.

[0052] In some embodiments, the first test parameter includes one or more of compression set, tensile strength, tear strength, elongation at break, and water absorption.

[0053] In some embodiments, the second test parameter includes one or more of compression set, tensile strength, tear strength, elongation at break, and water absorption.

[0054] In some implementations, selecting influencing factors and their levels from a plurality of single-factor test conditions according to the first test parameter group includes:

[0055] The change rate of the first test parameter after the single factor aging test relative to the initial parameter of the unaged rubber sealing material is calculated; and the influencing factors and their levels are selected in the single factor test conditions according to the change rate.

[0056] The initial parameters include one or more of compression set, tensile strength, tear strength, elongation at break and water absorption. It can be understood that the initial parameters at least need to include all physical quantities of the first test parameter.

[0057] The change rate Y of the first test parameter relative to the initial parameter of the unaged rubber sealing material i The calculation is done using the following formula:

[0058]

[0059] Where: y 0 is the initial parameter of the rubber sealing material before aging; i It is the first test parameter of the unaged rubber sealing material at a certain aging time; it is the change rate of the first physical parameter of the unaged rubber sealing material after a certain aging time relative to the unaged state.

[0060] In some implementations, selecting influencing factors and their levels in a single factor test condition according to the rate of change includes:

[0061] The single factors and their levels corresponding to the change rate ≥ 10% were selected as the influencing factors and their levels.

[0062] In this step, when there are multiple first test parameters, single factors and their levels whose change rates of all first test parameters are greater than or equal to 10% are selected as influencing factors and their levels.

[0063] In some embodiments, the first test parameter is the compression set rate. The compression set rate is an important parameter that reflects the changes in the internal microstructure of the material and evaluates the mechanical properties of the material. Using the compression set rate as an aging indication basis for the rubber sealing material can accurately match and indicate the actual aging behavior of the rubber sealing material.

[0064] In some embodiments, at least one of the influencing factors is combined with the test factor according to an orthogonal design experiment or a uniform design experiment. The orthogonal design experiment or the uniform design experiment can significantly reduce the number of groups of the experiment under the premise of ensuring uniform distribution of factors and levels.

[0065] In some embodiments, the single factor aging test includes one or more of a hot air aging test, a constant humidity and heat aging test, a low temperature aging test, an ultraviolet aging test, an acid salt spray test, and a swept frequency vibration test.

[0066] In some of the embodiments, an air aging chamber is used to perform an air heat aging test on an unaged rubber sealing material.

[0067] The aging test conditions of the air heat aging experiment are: the unaged rubber sealing material is subjected to constant temperature aging at different first temperature levels, the cumulative test is 240 hours, and the first test parameter of the aged rubber sealing material is characterized at least every 24 hours.

[0068] The first temperature level includes 70°C, 100°C, 125°C, and 150°C.

[0069] In some of the embodiments, an air aging chamber is used to perform a low-temperature aging test on an unaged rubber sealing material.

[0070] The aging test conditions of the low-temperature aging experiment are: the unaged rubber sealing material is subjected to constant temperature aging at different first temperature levels, the cumulative test is 96 hours, and the first test parameter of the aged rubber sealing material is characterized at least every 16 hours.

[0071] The second temperature level includes -20°C, -33°C, and -50°C.

[0072] In some of the embodiments, a programmable constant temperature and humidity testing machine is used to perform a constant humidity and heat aging experiment on an unaged rubber sealing material sample.

[0073] The aging test conditions of the constant humidity and heat aging experiment are as follows: the unaged rubber sealing material is subjected to constant temperature aging in different first humidity and heat environments, and the cumulative test is 20 days, and the first test parameter of the aged rubber sealing material is characterized at least every 4 days.

[0074] Among them, the first hot and humid environment includes: temperature 80±2℃, humidity 85±3%; temperature 80±2℃, humidity 93±3%; temperature 90±2℃, humidity 93±3%.

[0075] In some embodiments, a periodic UV exposure test is performed on the unaged sealing material using a UV test chamber with a UVA-340 fluorescent UV lamp.

[0076] The aging test conditions of the UV aging experiment are: exposing the unaged rubber sealing material to a dry radiation environment for 8 hours and to a condensing environment for 4 hours in turn; the cyclic exposure is performed for a total of 5 cycles, and at least the first test parameter of the aged rubber sealing material is characterized at the end of each cycle.

[0077] The conditions of the dry radiation environment include: temperature 60±3℃, irradiance 0.89±0.02W / m 2 ×nm, relative humidity 20%. The conditions of the condensation environment include: temperature 50±3℃, relative humidity 100%.

[0078] In some embodiments, an acid salt spray test is performed on the unaged sealing material using a salt spray chamber and a damp heat chamber.

[0079] The aging test conditions of the acid salt spray test are: expose the unaged rubber sealing material to a salt spray environment at 25°C for 2 hours, and then store it in a second wet and hot environment at 40°C for 20 hours, with a total of 10 cycles of cyclic exposure. At the end of at least every two cycles, the first test parameter of the aged rubber sealing material is characterized.

[0080] Among them, the conditions of the salt spray environment include: relative humidity 80%; relative humidity 90%; relative humidity 100%.

[0081] The second hot and humid environment includes: relative humidity 90%; relative humidity 93%; relative humidity 95%.

[0082] In some of the embodiments, the set aging test conditions of the swept frequency vibration test are: the unaged rubber sealing material is subjected to a swept frequency vibration test at a sweep rate of 1 octave / min and a sweep cycle number of 500 under different swept frequency ranges, and the first test parameter of the aged rubber sealing material is characterized after at least every 50 cycles.

[0083] Among them, the sweep frequency range includes: 0.1~1000Hz; 5~2000Hz; 10~3000Hz; 55~5000Hz.

[0084] In some embodiments, the test factors and their levels include one or more of stress factors and their levels and medium factors and their levels.

[0085] In some embodiments, the level of the stress factor includes one or more of: compression force 2000N, compression force 3000N, compression force 4000N, 20% compression rate, 25% compression rate, 30% compression rate.

[0086] In some embodiments, the level of medium factors includes one or both of oil medium and water medium.

[0087] The method for determining the multi-factor accelerated aging conditions of rubber sealing materials in the present application first conducts a single-factor aging test, and then selects typical aging influencing factors and their levels based on the results of the single-factor aging test, thereby achieving precise focusing on the main degradation influencing factors and their levels, effectively narrowing the selection range of factors and their levels of the multi-factor test, and shortening the result acquisition cycle of the multi-factor accelerated aging while ensuring accuracy.

[0088] In a second aspect of the present application, a multi-factor artificial accelerated aging test method for rubber sealing materials is provided. The accelerated aging conditions of the multi-factor artificial accelerated aging test are determined by using the above-mentioned method for determining the multi-factor accelerated aging conditions of rubber sealing materials.

[0089] In some embodiments, the method of multi-factor artificial accelerated aging test of rubber sealing materials includes:

[0090] The performance change curve of the second test parameter of the sealing material under the set multi-factor aging conditions as the aging time changes is drawn, and the influence of different factors and combination conditions on the material performance is compared; and the service life prediction model fits the performance change curve to analyze and predict the service life of the rubber sealing material under actual use conditions.

[0091] The multi-factor artificial accelerated aging experimental method for rubber sealing materials of the present application can more accurately analyze the aging performance of rubber sealing materials under actual conditions by taking into account multiple major aging influencing factors, which is beneficial to improving the reliability of predicting the service life of rubber sealing materials under comprehensive environmental conditions.

[0092] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. A method for determining multi-factor accelerated aging conditions of rubber sealing materials, characterized in that: The steps include: Test the initial parameters of unaged rubber sealing materials; Using multiple single-factor test conditions to perform single-factor aging tests on unaged rubber sealing materials, respectively, to obtain first test parameter groups corresponding to multiple single-factor aging tests and including first test parameters at multiple aging times; Selecting influencing factors and their levels from a plurality of the single-factor test conditions according to the first test parameter group; combining at least one of the influencing factors and its level with the test factor and its level to form a multi-factor test condition; Performing a multi-factor aging test on an unaged rubber sealing material under the multi-factor test conditions to obtain a second test parameter group including second test parameters at multiple aging times; The multi-factor accelerated aging conditions are determined according to the second test parameter group.

2. The method for determining the multi-factor accelerated aging conditions of rubber sealing materials according to claim 1, characterized in that: Determining the multi-factor accelerated aging condition according to the second test parameter group includes: Characterizing the correlation between the second test parameter and the aging time of the multi-factor aging test using the Pearson correlation coefficient r; The multi-factor test condition corresponding to the correlation coefficient r≤0.05 is selected as the accelerated aging condition.

3. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to claim 1, characterized in that: The selecting of influencing factors and their levels from the plurality of single factor test conditions according to the first test parameter group includes: Calculating the rate of change of the first test parameter after the single factor aging test relative to the initial parameter of the unaged rubber sealing material; The influencing factors and their levels are selected in the single factor test condition according to the change rate.

4. The method for determining the multi-factor accelerated aging conditions of rubber sealing materials according to claim 3, characterized in that: The selecting the influencing factor and its level in the single factor test condition according to the change rate comprises: The single factor and its level corresponding to the change rate ≥ 10% are selected as the influencing factor and its level.

5. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to any one of claims 1 to 4, characterized in that: At least one of the influencing factors and their levels is combined with a test factor and its level according to an orthogonal design experimental method or a uniform design experimental method.

6. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to any one of claims 1 to 4, characterized in that: The first test parameter includes one or more of compression set, tensile strength, tear strength, elongation at break and water absorption; and / or, The second test parameter includes one or more of compression set, tensile strength, tear strength, elongation at break and water absorption.

7. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to any one of claims 1 to 4, characterized in that: The single factor aging test includes one or more of a hot air aging test, a constant humidity and heat aging test, a low temperature aging test, an ultraviolet aging test, an acid salt spray test, and a swept frequency vibration test.

8. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to any one of claims 1 to 4, characterized in that: The test factors and their levels include one or more of stress factors and their levels and medium factors and their levels.

9. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to claim 8, characterized in that: The stress factors and their levels include: one or more of compression force 2000N, compression force 3000N, compression force 4000N, 20% compression rate, 25% compression rate, and 30% compression rate.

10. The method for determining multi-factor accelerated aging conditions of rubber sealing materials according to claim 8, characterized in that: The medium factors and their levels include one or both of an oil medium and a water medium.

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