Simulated aging test, repair and evaluation method of sealants

Abstract

The present invention relates to the technical field of simulated aging test for sealants, and provides a simulated aging test, repair, and evaluation method for sealants, comprising: measuring a first shear stress of a bonding surface; exposing the aging test surface of a second sample to air, and performing a simulated aging test on the aging test surface, wherein the simulated aging test includes an acid and alkali resistance test, an ultraviolet irradiation test, and a temperature alternation test; after the simulated aging test, cutting off the sealant from the aging test surface and along the axial direction of the second sample, filling and repairing the gap in the cut portion with sealant, measuring a second shear stress of the repaired bonding surface of the second sample, and comparing the second shear stress with the first shear stress. The present invention solves the defects of the prior art in that simulated aging and repair tests cannot accurately simulate the actual aging conditions of the bonding structure and the test data is not accurate enough, and has the advantages of a high degree of simulated aging simulation and accurate test data.

Description

Technical Field

[0001] The present invention relates to the technical field of sealant simulated aging test, and in particular to a sealant simulated aging test, repair and judgment evaluation method. Background Art

[0002] Adhesion, an indispensable connection method for rail vehicles, boasts engineering advantages such as ease of operation, low cost, stress-free operation, and sealing. In recent years, it has been widely used to connect critical structures such as side and front windows on rail passenger vehicles. During a vehicle's service life, bonded structures like windows must withstand harsh conditions such as high temperatures, extreme cold, and vibration. Routine maintenance also requires acid and alkali cleaning. Over time, these bonded structures can age, leading to problems such as water seepage and air leakage, posing a threat to vehicle reliability.

[0003] Therefore, whenever rail vehicles require extensive maintenance, simulated aging and repair tests are performed on adhesive structures, such as windows, to determine if the adhesive strength meets the required standards before they can be put back into service. However, existing simulated aging and repair tests often fail to accurately simulate the actual aging of adhesive structures, and the resulting test data is inaccurate. Summary of the Invention

[0004] The present invention provides a method for simulated aging testing, repairing and judging evaluation of sealants, which is used to solve the defects in the prior art that simulated aging and repair tests cannot accurately simulate the actual aging conditions of the bonding structure and the test data is not accurate enough. It has the advantages of high degree of simulated aging simulation and accurate test data.

[0005] The present invention provides a simulated aging test, repair, and evaluation method for a sealant, comprising: bonding a sealant to one end of a substrate to form a tensile shear joint, overlapping and bonding the end of the sealant at the tensile shear joint to one end of glass to form a tensile shear specimen, wherein the sealant includes an aging test surface facing the glass surface; the tensile shear specimen includes a first specimen and a second specimen; performing a tensile shear test on the first specimen to measure a first shear stress of the bonding surface; exposing the aging test surface of the second specimen to air and performing a simulated aging test on the aging test surface, wherein the simulated aging test includes an acid and alkali resistance test, an ultraviolet irradiation test, and a temperature alternation test; after the simulated aging test, cutting the sealant from the aging test surface and along the axial direction of the second specimen, filling and repairing a gap in the cut portion with the sealant, performing a tensile shear test on the repaired second specimen to measure a second shear stress of the bonding surface, and comparing the magnitude of the second shear stress with the first shear stress to determine whether the strength of the repaired second specimen is qualified.

[0006] According to a simulated aging test, repair, and evaluation method for a sealant provided by the present invention, the acid and alkali resistance test includes simulating aging under acidic conditions and aging under alkaline conditions on the aging test surface, respectively. The aging under acidic conditions includes placing the aging test surface in an acidic solution for 150 hours, and the aging under alkaline conditions includes placing the aging test surface in an alkaline solution for 150 hours.

[0007] According to a sealant simulated aging test, repair and evaluation method provided by the present invention, the ultraviolet irradiation test includes continuously irradiating the aging test surface with ultraviolet light.

[0008] According to a sealant simulation aging test, repair and evaluation method provided by the present invention, the intensity of the continuous ultraviolet irradiation is 1000 megajoules per square meter, and the time of the continuous ultraviolet irradiation is 1500 hours.

[0009] According to a sealant simulation aging test, repair and evaluation method provided by the present invention, the temperature alternation test includes a first temperature simulation test, a second temperature simulation test and a third temperature simulation test that are performed successively.

[0010] According to a simulated aging test, repair and evaluation method for a sealant provided by the present invention, the first temperature simulation test includes placing the aging test surface at 80°C and 95% humidity for 4 hours, the second temperature simulation test includes gradually cooling the aging test surface to -40°C within 2 hours and maintaining it at -40°C for 4 hours, and the third temperature simulation test includes gradually heating the aging test surface to 80°C within 2 hours.

[0011] According to a sealant simulation aging test, repair and evaluation method provided by the present invention, the first temperature simulation test, the second temperature simulation test and the third temperature simulation test together constitute a cycle, and the cycle is performed a total of 265 times.

[0012] According to the simulated aging test, repair and evaluation method of sealant provided by the present invention, the acid and alkali resistance test, the ultraviolet irradiation test and the temperature alternation test are respectively performed once and in any order.

[0013] According to the sealant simulated aging test, repair and evaluation method provided by the present invention, the thickness of the cut-off portion is greater than 1 mm.

[0014] According to the present invention, a simulated aging test, repair and evaluation method for a sealant further includes observing the adhesion of the sealant along an axis perpendicular to the second sample when the sealant is used to fill and repair the gap in the cut portion.

[0015] The simulated aging test, repair, and evaluation method for sealants provided by the present invention performs a comprehensive aging simulation test of acid and alkali resistance, ultraviolet irradiation, and temperature alternation on shear and tensile specimens of adhesive structures such as vehicle windows. This achieves the accumulation of factors affecting sealant aging and effectively restores the actual aging of the adhesive structure. The aged specimen is cut and refilled, and the repaired specimen is subjected to a tensile shear test. The shear stress of the repaired specimen is compared with the shear stress of the unaged specimen to determine whether the strength of the adhesive structure meets the standard, thereby evaluating whether it can continue to serve. The present invention solves the defects of the existing technology in that simulated aging and repair tests cannot accurately simulate the actual aging of the adhesive structure and the test data is not accurate. It has the advantages of a high degree of simulated aging simulation and accurate test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a flow chart of the simulated aging test, repair and evaluation method of the sealant provided by the present invention;

[0018] Figure 2 It is a schematic structural diagram of the tensile shear specimen of the present invention;

[0019] Figure 3 It is a schematic diagram of a cross section perpendicular to the axial direction of the tensile shear specimen of the present invention.

[0020] Reference numerals:

[0021] 1. Sealant; 11. Aging test surface; 12. Bonding surface; 2. Substrate; 3. Glass; 4. Tensile shear specimen. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0023] The following combination Figures 1 to 3The present invention describes a method for simulating aging test, repair and evaluation of a sealant. The method is suitable for simulating the aging process of adhesive structures such as windows and front windows of rail vehicles.

[0024] See also Figures 1 to 3 The present invention provides a method for simulated aging test, repair and evaluation of sealant, which specifically includes steps one to four.

[0025] In step 1, the sealant 1 is bonded to one end of the substrate 2 to form a tensile shear joint, and the end of the sealant 1 at the tensile shear joint is overlapped and bonded to one end of the glass 3 to form a tensile shear specimen 4. The sealant 1 includes an aging test surface 11 facing the surface of the glass 3; the tensile shear specimen 4 includes a first specimen and a second specimen.

[0026] In this embodiment, the surface of the glass 3 is parallel to the surface of the substrate 2, the length direction of the glass 3 is coaxial with the length direction of the substrate 2, and the cross-section of the sealant 1 perpendicular to the axial direction of the tensile shear specimen 4 is rectangular. The areas of the bonding surface 12 between the sealant 1 and the glass 3 and the bonding surface 12 between the sealant 1 and the substrate 2 are equal, and the length of each bonding surface 12 along the axial direction of the tensile shear specimen 4 is 12.5 mm ± 0.25 mm.

[0027] It can be understood that the purpose of step one is to prepare samples of bonding structures such as windows and front windows in rail vehicles, where the glass 3 corresponds to the windows, front windows and other windows, and the substrate 2 corresponds to the body of the rail vehicle. The glass 3 and the substrate 2 are bonded together by the sealant 1. The material selection requirements of the glass 3 and the substrate 2 should comply with the relevant standards, which will not be elaborated here.

[0028] Step 2: Perform a tensile shear test on the first sample to measure the first shear stress of the bonding surface 12.

[0029] Specifically, a clamp is used to clamp the ends of the substrate 2 and the glass 3 that are away from each other, and then a tensile force is applied to the first specimen using a tensile testing machine. The direction of the tensile force is parallel to the bonding surface 12 between the sealant 1 and the glass 3 and along the axial direction of the first specimen. The magnitude of the first shear stress is equal to the maximum load that causes shear failure of the first specimen divided by the area of ​​the bonding surface 12.

[0030] It can be understood that the aging test surface 11 is the surface of the sealant 1 that is perpendicular to the bonding surface 12 and is closer to the clamping end of the glass 3 .

[0031] Step three: expose the aging test surface 11 of the second sample to air and perform a simulated aging test on the aging test surface 11. The simulated aging test includes an acid and alkali resistance test, an ultraviolet irradiation test, and a temperature alternation test.

[0032] It can be understood that the aging test surface 11 corresponds to the surface of the bonding structure such as the vehicle window located outdoors, the acid and alkali resistance test corresponds to the aging process of the sealant 1 after acid washing and alkaline washing during the daily maintenance of the vehicle, the ultraviolet irradiation test corresponds to the aging process of the sealant 1 due to the sun's ultraviolet rays during the service of the vehicle, and the temperature alternation test corresponds to the aging process of the sealant 1 under the influence of severe cold and heat during the service of the vehicle.

[0033] It is understandable that for sealant 1, pH, ultraviolet light, and extreme temperatures are the primary factors that accelerate its aging. However, for glass 3 and substrate 2, these factors have minimal, negligible impact on their aging and damage. Therefore, the present invention, through a variable control method, conducts comprehensive simulation tests on sealant 1 under the aforementioned influencing factors. This achieves the accumulation of factors influencing sealant 1 aging, effectively reproducing the actual aging conditions of bonded structures such as vehicle windows, and laying a solid foundation for the accuracy of the test data.

[0034] Step 4: After the simulated aging test, the sealant 1 is cut off from the aging test surface 11 and along the axial direction of the second sample, and the gap in the cut part is filled and repaired with the sealant 1. The repaired second sample is subjected to a tensile shear test, and the second shear stress of the bonding surface 12 is measured. The magnitude relationship between the second shear stress and the first shear stress is compared to determine whether the strength of the repaired second sample is qualified.

[0035] Specifically, the magnitude of the second shear stress is equal to the maximum load at which the second specimen fails in shear divided by the area of ​​the bonding surface 12. If the second shear stress is greater than or equal to the first shear stress, the strength of the second specimen is considered acceptable, confirming that the bonded structure, such as a rail vehicle window, meets the requirements and is suitable for return to service. The tensile shear test in step 4 is performed identically to the test in step 2 and will not be further elaborated upon here.

[0036] The present invention provides a method for simulated aging testing, repair, and evaluation of sealant 1. By subjecting shear and tensile specimens of adhesive structures such as vehicle windows to a comprehensive aging simulation test, including acid and alkali resistance testing, UV irradiation testing, and temperature alternation testing, the method achieves the accumulation of factors affecting the aging of sealant 1 and effectively restores the actual aging of the adhesive structure. The aged specimen is excised and refilled, and the repaired specimen is subjected to a tensile shear test. The shear stress of the repaired specimen is compared with the shear stress of the unaged specimen to determine whether the strength of the adhesive structure meets the standard, thereby evaluating whether it can continue to serve. The present invention solves the defects of the prior art in that simulated aging and repair tests cannot accurately simulate the actual aging of the adhesive structure and the test data is not accurate. It has the advantages of a high degree of simulated aging simulation and accurate test data.

[0037] See also Figures 1 to 3 The acid and alkali resistance test includes simulating the aging test surface 11 under acidic conditions and aging under alkaline conditions respectively. The aging under acidic conditions includes placing the aging test surface 11 in an acidic solution for 150 hours, and the aging under alkaline conditions includes placing the aging test surface 11 in an alkaline solution for 150 hours.

[0038] Specifically, assuming a daily cleaning frequency, excluding maintenance, there are 300 cleanings per year. Given a 12-year service life for the train, the total number of cleanings is 3,600. Each cleaning session includes 2.5 minutes of acid cleaning and 2.5 minutes of alkaline cleaning, resulting in a total of 150 hours of acid cleaning and 150 hours of alkaline cleaning, corresponding to the immersion time of the aging test surface 11 in the acidic and alkaline solutions, respectively, during the acid and alkali resistance tests.

[0039] It should be noted that there is no requirement for the order in which the aging test surface 11 is immersed in the acidic solution or the alkaline solution.

[0040] See also Figures 1 to 3 The ultraviolet irradiation test includes continuously irradiating the aging test surface 11 with ultraviolet light, the intensity of the continuous ultraviolet irradiation is 1000 megajoules per square meter, and the time of the continuous ultraviolet irradiation is 1500 hours.

[0041] Specifically, the annual average ultraviolet radiation intensity of the train is estimated to be 120 megajoules per square meter. Taking into account starting and stopping, tunnels, maintenance, etc., 70% of the radiation dose is taken, and the total ultraviolet radiation intensity for 12 years is 1008 megajoules per square meter; therefore, the continuous ultraviolet radiation intensity of the ultraviolet irradiation test is set to 1000 megajoules per square meter.

[0042] On the other hand, laboratory UV accelerated testing according to GB / T14522-2008 requires 8000 hours of continuous exposure. However, during the UV test, infrared spectroscopy analysis of sealant 1 at 1500 and 3000 hours revealed that UV damage to sealant 1 was identical at both time points, limited to within a 1 mm thickness from the aging test surface 11. Therefore, further extension of the UV exposure time would not yield a cumulative UV damage depth. Considering economic efficiency and cycle time, the continuous UV exposure time for the UV irradiation test was selected to be 1500 hours.

[0043] See also Figures 1 to 3 The temperature alternation test includes a first temperature simulation test, a second temperature simulation test, and a third temperature simulation test that are performed successively. The first temperature simulation test, the second temperature simulation test, and the third temperature simulation test together constitute a cycle, and the cycle is performed a total of 265 times.

[0044] Specifically, the train will run a total of 2121 one-way trips during its service life, including both outbound and return trips. A quarter of these trips occur in the summer. Therefore, if the train's first one-way run is the outbound trip in the summer, the train will run four times each way (repeated twice between the outbound and return trips), with the last of these trips occurring in the summer. Therefore, excluding the first summer run, the train will experience exactly (2121-1) / 4=530 summer runs, and the 2121st run will also be in the summer. If "each entry into or exit from summer after the first run" is counted as one cycle, then there will be a total of 530 / 2=265 cycles, which is the basis for setting the number of cycles to 265 in the temperature alternation test.

[0045] In this embodiment, the temperature alternation test uses extreme temperature conditions to simulate seasonal changes: the first temperature simulation test involves exposing the aging test surface 11 to 80°C and 95% humidity for 4 hours (equivalent to simulating summer); the second temperature simulation test involves gradually cooling the aging test surface 11 to -40°C over 2 hours (equivalent to simulating autumn) and maintaining it at -40°C for 4 hours (equivalent to simulating winter); and the third temperature simulation test involves gradually heating the aging test surface 11 to 80°C over 2 hours (equivalent to simulating spring and then back to summer). This completes one cycle, and the next temperature alternation test cycle begins.

[0046] It should be noted that the acid and alkali resistance test, ultraviolet irradiation test and temperature alternation test are each conducted once and in any order, because the test is about the accumulation of aging influencing factors of the sealant 1, and there is no strict limit on the order of the three types of aging simulation tests.

[0047] See also Figures 1 to 3 In step 4, when filling the gap in the removed portion with sealant 1, the adhesion of sealant 1 is also observed along an axis perpendicular to the second specimen. This allows for timely filling of any holes created during the repair process, helping to improve the integrity of sealant 1 and the accuracy of subsequent tensile shear tests.

[0048] See also Figure 2 and Figure 3 , the thickness of the removed part is greater than 1 mm.

[0049] Specifically, since the UV irradiation test determined that the damage to the sealant 1 occurred only within 1 mm of the aging test surface 11, the cut thickness only needs to be greater than 1 mm. In this embodiment, the minimum thickness of the cut portion is 1.5 mm.

[0050] To accurately remove the 1.5 mm thick sealant 1, the following method was used: First, a 3 mm distance from the aging test surface 11 was determined along the axis of the second specimen and marked on both the glass 3 and substrate 2. Next, a bevel cut was made from the junction of the glass 3 and the aging test surface 11 toward the 3 mm mark on the substrate 2. Finally, a bevel cut was made from the junction of the substrate 2 and the aging test surface 11 toward the 3 mm mark on the glass 3. Since the cross-section of the sealant 1 perpendicular to the axis of the second specimen is rectangular, geometric principles indicate that the distance from the intersection of the two beveled lines to the aging test surface 11 is 1.5 mm. Finally, the corresponding portion of the sealant 1 was removed along the adhesive surface 12.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for simulated aging test, repair and evaluation of sealant, characterized in that: include: Bonding a sealant to one end of a substrate to form a tensile shear joint, overlapping and bonding an end of the sealant at the tensile shear joint to one end of a glass to form a tensile shear specimen, wherein the sealant includes an aging test surface facing the glass surface; The tensile shear specimen includes a first specimen and a second specimen; Performing a tensile shear test on the first sample to measure a first shear stress of the bonding surface; exposing the aging test surface of the second sample to air and performing a simulated aging test on the aging test surface, wherein the simulated aging test includes an acid and alkali resistance test, an ultraviolet irradiation test, and a temperature alternation test; After the simulated aging test, the sealant is cut off from the aging test surface and along the axial direction of the second specimen, and the gap in the cut portion is filled and repaired with the sealant. A tensile shear test is performed on the repaired second specimen to measure the second shear stress of the bonding surface. The second shear stress is compared with the first shear stress to determine whether the strength of the repaired second specimen is qualified.

2. The sealant simulated aging test, repair and evaluation method according to claim 1, characterized in that: The acid and alkali resistance test includes simulating aging under acidic conditions and aging under alkaline conditions on the aging test surface, respectively. The aging under acidic conditions includes placing the aging test surface in an acidic solution for 150 hours, and the aging under alkaline conditions includes placing the aging test surface in an alkaline solution for 150 hours.

3. The sealant simulated aging test, repair and evaluation method according to claim 1, characterized in that: The ultraviolet irradiation test includes continuously irradiating the aging test surface with ultraviolet light.

4. The sealant simulated aging test, repair and evaluation method according to claim 3, characterized in that: The intensity of the continuous ultraviolet irradiation is 1000 megajoules per square meter, and the time of the continuous ultraviolet irradiation is 1500 hours.

5. The sealant simulated aging test, repair and evaluation method according to claim 1, characterized in that: The temperature alternation test includes a first temperature simulation test, a second temperature simulation test and a third temperature simulation test which are performed successively.

6. The sealant simulated aging test, repair and evaluation method according to claim 5, characterized in that: The first temperature simulation test includes placing the aging test surface at 80°C and 95% humidity for 4 hours, the second temperature simulation test includes gradually cooling the aging test surface to -40°C within 2 hours and maintaining it at -40°C for 4 hours, and the third temperature simulation test includes gradually heating the aging test surface to 80°C within 2 hours.

7. The sealant simulated aging test, repair and evaluation method according to claim 6, characterized in that: The first temperature simulation test, the second temperature simulation test, and the third temperature simulation test together constitute a cycle, and the cycle is performed 265 times in total.

8. The method for simulated aging test, repair and evaluation of sealant according to any one of claims 1 to 7, characterized in that: The acid and alkali resistance test, the ultraviolet irradiation test and the temperature alternation test are respectively carried out once and in any order.

9. The sealant simulated aging test, repair and evaluation method according to claim 8, characterized in that: The thickness of the cut-off portion is greater than 1 mm.

10. The sealant simulated aging test, repair and evaluation method according to claim 8, characterized in that: The method further includes observing the adhesion of the sealant along an axis perpendicular to the second sample when the sealant is used to fill and repair the gap in the cut portion.

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