Equivalent acceleration experiment method for ion migration of ceramic material

Abstract

The invention discloses an equivalent acceleration experiment method for ceramic material ion migration, and belongs to the technical field of ceramic material deterioration experiments. The method comprises the following steps: acquiring a deterioration characteristic quantity of a ceramic material under an actual working condition, simulating conditions under the actual working condition through a ceramic material ion migration deterioration characteristic quantity testing device, further performing a deterioration experiment on the ceramic material, taking out the ceramic material at an interval of 5-10 days, and measuring a performance index of the ceramic material as the deterioration characteristic quantity; performing data analysis on the deterioration characteristic quantity obtained by testing, and selecting the characteristic quantity with a linear relationship between the deterioration characteristic quantity and the deterioration time as a deterioration characteristic index; external conditions are changed, so that the ceramic material reaches the same degradation degree under the actual working condition within 5-15 days, and the experiment acceleration coefficient after the external conditions are changed is calculated according to time. According to the method, the time of an ion migration experiment can be effectively shortened, the external environment conditions of ceramic materials with different morphologies under various working conditions are met, and the obtained characteristic quantity result of ion migration degradation is accurate.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic material degradation experiments, and in particular to an equivalent accelerated experimental method for ion migration of ceramic materials. Background Art

[0002] With the continuous and rapid development of my country's power system, the safe and stable operation of related power equipment is facing greater and greater challenges. Improving the stability and safety of the power system is of great significance to ensuring the quality of life of the people and the steady and rapid development of the economy. Ceramic insulators are widely used in high-voltage power transmission and transformation equipment due to their good insulation and mechanical properties, and are the key insulation structure of high-voltage equipment. However, in recent years, high-voltage AC and DC power transmission equipment operation failures have occurred from time to time, among which the insulation failure of the core insulation parts in the equipment accounts for a large proportion of equipment failures. The fundamental reason is that the basic insulation materials used in the equipment are difficult to withstand the long-term electrical, thermal, mechanical and other comprehensive stresses of the equipment, thereby causing long-term insulation failure of the material.

[0003] For ceramic materials, existing studies have shown that under the action of electric and thermal fields, the main factor causing ceramic material failure is the migration of ions inside it. Under the action of long-term DC electric fields, the ions inside the ceramic material will migrate and generate local expansion stress, causing microcracks and eventually developing into breakdown, which poses a great safety hazard to the safe operation of power equipment and even power systems. Existing accelerated degradation experiments are mostly for organic insulating materials, using methods such as half-life temperature difference for accelerated estimation. However, ceramic materials are inorganic materials, and their half-life temperature difference is difficult to measure, and the measurement time is also very long.

[0004] Therefore, in view of the applicability and time cost issues of the current ceramic material ion migration degradation experimental method, there is an urgent need for an equivalent accelerated experimental method that can be applied to ceramic materials and can effectively shorten the ion migration time. Summary of the invention

[0005] The purpose of the present invention is to provide an equivalent accelerated experimental method for ion migration of ceramic materials, comprising the following steps:

[0006] Obtain the degradation characteristic quantity of the ceramic material under actual working conditions, simulate the conditions under actual working conditions through the ceramic material ion migration degradation characteristic quantity testing device, and then conduct a degradation experiment on the ceramic material, take out and measure the performance index of the ceramic material at intervals of 5 to 10 days as the degradation characteristic quantity;

[0007] Perform data analysis on the degradation characteristic quantities obtained from the test, and select characteristic quantities with a linear relationship between the degradation characteristic quantity and the degradation time as degradation characteristic indicators;

[0008] The external conditions are changed so that the ceramic material reaches the same degree of deterioration as under actual working conditions within 5 to 15 days, and the experimental acceleration coefficient after the external conditions are changed is calculated based on the time.

[0009] The degradation characteristic quantity is one of bending strength, surface trap energy level, and flashover field strength.

[0010] The ceramic material ion migration degradation characteristic quantity test device includes a high-voltage module, a closed cavity, a temperature control module, an upper plate, a lower plate, an air inlet, and an exhaust port;

[0011] Among them, the high-voltage module is located at the top of the closed cavity, the upper electrode plate is arranged below the high-voltage module, the closed cavity is provided with an air inlet and an exhaust port, and the temperature control module is arranged on the lower side of the lower plate.

[0012] The height of the lower plate is adjustable.

[0013] A ceramic sample is placed between the upper plate and the lower plate.

[0014] The beneficial effects of the present invention are:

[0015] (1) The present invention applies stronger stress to the ceramic material by changing the external conditions, and the acceleration relationship between the stronger stress and the normal working condition can be obtained by calculation, thereby effectively reducing the time of the ion migration experiment.

[0016] (2) The ceramic material ion migration degradation characteristic quantity testing device of the present invention includes a high-voltage module, a closed cavity and a temperature control module, and the lower plate can move up and down, which can meet the external environmental conditions of ceramic materials with different morphologies under various working conditions, and the obtained ion migration degradation characteristic quantity results are accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of an equivalent accelerated experimental method for ion migration of ceramic materials of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the testing device for the characteristic quantity of ion migration degradation of ceramic materials. DETAILED DESCRIPTION

[0019] The present invention provides an equivalent acceleration experimental method for ion migration of ceramic materials, which will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] Figure 1This is a flow chart of the equivalent accelerated experimental method for ion migration of ceramic materials of the present invention; the specific method includes obtaining the degradation characteristic quantity of the ceramic material under actual working conditions, selecting appropriate characteristic indicators by analyzing the relationship between the characteristic quantity and the degradation time, and realizing the accelerated degradation of ion migration by changing the external conditions. First, obtain the degradation characteristic quantity of the ceramic material under actual working conditions, simulate the conditions under actual working conditions through the ceramic material ion migration degradation characteristic quantity testing device to conduct degradation experiments on the ceramic material, take out and measure the performance indicators of the ceramic material as degradation characteristic quantities (bending strength, surface trap energy level, flashover field strength) at intervals of 5 to 10 days (total experimental period of 30-50 days); second, perform data analysis on the degradation characteristic quantity obtained by the test, and find the characteristic quantity with a linear relationship between the degradation characteristic quantity and the degradation time as the characteristic indicator; third, change the external conditions so that the ceramic material reaches the same degree of degradation under actual working conditions in 5 to 15 days, and then calculate the experimental acceleration coefficient after changing the external conditions according to the time, and then obtain the direct conversion relationship between the two conditions. The specific derivation process is as follows:

[0021] The reaction activation energy can be used to obtain the ratio of the reaction rates tested under two different temperature conditions.

[0022] For the determination of reaction activation energy, the formula for the reaction rate can be expressed as:

[0023]

[0024] Where t is time; A is the characteristic constant of a given reaction, called the pre-exponential factor. Since the degradation experiment does not change the nature of the chemical reaction, it can be ignored in this calculation; R is the gas constant (8.314 J·mol -1 ·K -1 ); T is the thermodynamic temperature (K); Ea is the reaction activation energy (kJ·mol -1 ).

[0025] Where P is the characteristic index of ion migration degradation of ceramic materials. Assuming that the degradation amount in the initial state (i.e., no degradation) is P1, the corresponding time is t1; the degradation amount in another state is P2, the corresponding time is t2, the following deduction can be made based on the above formula:

[0026] The accumulated degradation is

[0027]

[0028]

[0029]

[0030] Take the logarithm

[0031]

[0032] Then for a material degradation test, a degradation amount P can be determined. The state is a characteristic that will degrade over time during the degradation test (the initial state corresponds to 100%, and the degradation amount is x% of the initial state). For the material, the test is conducted at two temperatures, T1 and T2, and the time to reach P at different temperatures is recorded, and the following formula can be obtained:

[0033]

[0034]

[0035] Since the degenerate quantities are consistent, the combined difference can be obtained:

[0036]

[0037] At this time, all quantities except the activation energy are known, so Ea can be calculated. Through the activation energy data obtained from the experiment, the acceleration coefficient of the test temperature (T2) relative to the normal operating condition (T1) can be obtained, and the test equivalent time of the two can be determined.

[0038] Figure 2 The schematic diagram of the structure of the ceramic material ion migration degradation characteristic quantity test device is shown in FIG. The high-voltage module 1 is located at the top of the closed cavity 2, connected to the high-voltage AC / DC power supply through the high-voltage lead, and connected to the upper plate 5 below. The ceramic sample 3 is placed between the upper plate 5 and the lower plate 6, and the high-voltage module 1 simulates the electric field environment under actual working conditions.

[0039] In the device, the closed cavity 2 is provided with an air inlet 7 and an exhaust port 8, so as to simulate the actual working conditions and inject corresponding gas, and the gas pressure is controllable.

[0040] In the device, the temperature control module 4 is arranged at the lower end of the lower plate 6, which can control the temperature of the lower plate 6 and thus control the temperature condition of the entire ceramic material. The lower plate 6 as a whole can adjust the height to meet the experiment of ceramic materials of different sizes.

[0041] Example 1

[0042] Taking the bending strength of ceramic materials as the characteristic indicator of degradation, according to the electric field strength under working conditions, after 40 days of operation at 40°C, the bending strength dropped to 95% of the original. Changing the temperature condition to 140°C, after 10 days of operation, the bending strength dropped to 95% of the original. According to the above principle, the acceleration factor at 140°C is about 76, that is, the 30-year ion migration experiment can be completed in only about 0.395 years, about 144 days.

[0043] Example 2

[0044] Taking the surface trap energy level of ceramic materials as the degradation characteristic indicator, according to the electric field strength under the working conditions, after running at 40°C for 40 days, the surface trap energy level dropped to 95% of the original. Changing the temperature condition to 160°C, after running for 8 days, the trap energy level dropped to 95% of the original. According to the above principle, the acceleration factor at 160°C is about 66, that is, the 30-year ion migration experiment can be completed in only about 0.455 years, about 167 days.

[0045] The present invention can effectively reduce the time of ion migration experiments, can meet the external environmental conditions of ceramic materials with different morphologies under various working conditions, and the obtained characteristic quantity results of ion migration degradation are accurate.

Claims

1. An equivalent accelerated experimental method for ion migration of ceramic materials, characterized in that: The following steps are involved: Obtain the degradation characteristic quantity of the ceramic material under actual working conditions, simulate the conditions under actual working conditions through the ceramic material ion migration degradation characteristic quantity testing device, and then conduct a degradation experiment on the ceramic material, take out and measure the performance index of the ceramic material at intervals of 5 to 10 days as the degradation characteristic quantity; Perform data analysis on the degradation characteristic quantities obtained from the test, and select characteristic quantities with a linear relationship between the degradation characteristic quantity and the degradation time as degradation characteristic indicators; The external conditions are changed so that the ceramic material reaches the same degree of deterioration as under actual working conditions within 5 to 15 days, and the experimental acceleration coefficient after the external conditions are changed is calculated based on the time.

2. The equivalent accelerated experimental method for ion migration of ceramic materials according to claim 1, characterized in that: The degradation characteristic quantity is one of bending strength, surface trap energy level, and flashover field strength.

3. The equivalent accelerated experimental method for ion migration of ceramic materials according to claim 1, characterized in that: The ceramic material ion migration degradation characteristic quantity testing device comprises a high voltage module (1), a closed cavity (2), a temperature control module (4), an upper plate (5), a lower plate (6), an air inlet (7), and an exhaust port (8); The high-voltage module (1) is located at the top of the sealed cavity (2), the upper electrode plate (5) is arranged below the high-voltage module (1), the sealed cavity (2) is provided with an air inlet (7) and an exhaust port (8), and the temperature control module (4) is arranged on the lower side of the lower plate (6).

4. The equivalent accelerated experimental method for ion migration of ceramic materials according to claim 3, characterized in that: The height of the lower plate (6) is adjustable.

5. The equivalent accelerated test method for ion migration of ceramic materials according to claim 3 or 4, characterized in that: A ceramic sample (3) is placed between the upper plate (5) and the lower plate (6).

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