A corrosion test method suitable for adapting the corrosion strength of a passenger car to the domestic environment

Abstract

The application discloses a kind of corrosion test methods suitable for domestic passenger car corrosion intensity in the technical field of automobile material corrosion evaluation;The method is placed in the circulating corrosion test box after washing, wiping, drying, scratch, shielding and weighing to the passenger car to be tested;Then by deionized water, sodium chloride, calcium chloride dihydrate, magnesium chloride hexahydrate, anhydrous sodium sulfate, sodium nitrate, ammonium chloride, sodium bicarbonate and iron manganese sulfur nitrate silicon complex corrosion-promoting microspheres Compound corrosion solution is prepared;Subsequently, salt spray deposition, wet heat penetration, hot air drying and normal temperature rehydration cycle processing are carried out in turn, and the corrosion performance test is carried out on the corrosion sample to be tested.The application can simulate the chlorine salt, wet heat and dry-wet alternating corrosion environment in the service of domestic passenger car, improve the adaptability and distinguish degree of corrosion intensity evaluation.

Description

Technical Field

[0001] This invention belongs to the field of automotive material corrosion evaluation technology, specifically relating to a corrosion testing method adapted to the corrosion intensity of passenger vehicles in China. Background Technology

[0002] Passenger vehicles are exposed to complex and variable atmospheric, road, and cleaning / maintenance environments during their actual service life. Body panels, chassis components, welded joints, paint scratches, flange gaps, and fastening areas are all susceptible to varying degrees of corrosion. my country has a vast territory with significantly different corrosive environments across regions. Coastal areas have higher air salt content, roads in northern regions are easily affected by snow-melting salt in winter, and southern regions experience prolonged periods of high temperature and humidity. Urban road environments may also contain various corrosive factors such as sulfates, nitrates, ammonium salts, silt, and stagnant water. These factors often do not act alone but rather work together under alternating conditions of humidity, dryness, moisture regain, and temperature fluctuations to influence the corrosion behavior of metal substrates, plating, and coatings. This leads to problems such as scratch-borne corrosion, edge corrosion, pitting, crevice corrosion, red rust, and coating blistering in passenger vehicle parts, ultimately affecting the vehicle's appearance quality, structural durability, and operational safety.

[0003] Existing corrosion evaluation methods for passenger vehicles mostly employ accelerated testing with a single salt spray or a fixed corrosive medium. While these methods are simple to operate and have good repeatability, their composition of the corrosive medium and environmental transitions are relatively limited, making it difficult to fully reflect the comprehensive corrosion characteristics of passenger vehicles in actual use in China, which involve multiple salt concentrations, pollutants, and variations in humidity and temperature, as well as alternating wet and dry conditions. Continuous salt spray conditions can easily cause samples to be in an over-wetted state for extended periods, failing to fully reflect actual corrosion processes such as salt crystallization, rehygroscopicity, localized concentration, undercoating expansion, and electrolyte retention within crevices. Furthermore, the corrosion morphology of different material systems in continuous salt spray may differ from that after road service, resulting in insufficient ability to distinguish corrosion intensity differences between painted panels, galvanized panels, aluminum alloy parts, flanged structures, and chassis components. Therefore, existing technologies still require a corrosion intensity evaluation method that more closely approximates the service environment of passenger vehicles in China to improve the correlation between laboratory test results and actual road corrosion performance.

[0004] Furthermore, existing corrosion test solutions typically use chloride salts as the main component, which are insufficient for comprehensively simulating the hygroscopic effects of calcium and magnesium salts, the acidic precipitation effects of sulfates and nitrates, the influence of ammonium salts, and the weak buffering environment. The deposition uniformity and retention stability of the corrosion solution in scratches, edges, pores, and crevice areas are also limited, easily leading to excessively strong or weak localized corrosion and significant data dispersion between parallel samples. For passenger vehicle corrosion intensity evaluation, relying solely on ordinary salt solutions is insufficient to stably induce a composite corrosion morphology similar to the actual service environment, and it is also difficult to account for the influence of different corrosion factors on the test results. Therefore, it is necessary to provide a passenger vehicle corrosion test method adapted to the domestic corrosion intensity characteristics. By rationally configuring the corrosion medium and introducing iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres that can improve the deposition and retention of the corrosion medium, the test can more stably simulate the corrosion process of domestic passenger vehicles under chloride salt, humid heat, acidic precipitation, and alternating wet and dry conditions. This will provide a more reliable technical basis for body material selection, coating system evaluation, and component corrosion resistance verification. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a corrosion testing method that is suitable for the corrosion intensity of passenger vehicles in China.

[0006] In a first aspect, the present invention provides a corrosion testing method adapted to the corrosion intensity of passenger vehicles in China, comprising the following steps:

[0007] S1. Wash the passenger vehicle test sample with deionized water, wipe it with anhydrous ethanol, and dry it at 45-55℃ to obtain the pretreated passenger vehicle test sample; prepare scratches on the test surface of the pretreated passenger vehicle test sample and mask the non-evaluation surface to obtain the prepared passenger vehicle test sample; weigh the prepared passenger vehicle test sample and record the initial mass, and then put it into the cyclic corrosion test chamber.

[0008] S2. By weight, add 990-1010 parts of deionized water to a container, then add 8.0-12.0 parts of sodium chloride, 1.0-2.0 parts of calcium chloride dihydrate, 0.5-1.0 parts of magnesium chloride hexahydrate, 0.8-1.5 parts of anhydrous sodium sulfate, 0.3-0.8 parts of sodium nitrate, 0.2-0.5 parts of ammonium chloride, and 0.3-0.8 parts of sodium bicarbonate. Stir to obtain a basic etching solution. Add 0.03-0.08 parts of iron-manganese-sulfur-nitrate-silicon complexed etching-promoting microspheres to the basic etching solution, disperse, and adjust the pH to obtain a composite etching solution.

[0009] S3. Add the composite corrosion solution to the cyclic corrosion test chamber and sequentially perform salt spray deposition, wet heat penetration, hot air drying and room temperature rehumidification cycle treatment on the prepared passenger car test sample to obtain the corroded test sample.

[0010] S4. Take out the corroded test sample, rinse it with deionized water, and dry it to obtain the pretreated corroded test sample; test the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss and crevice corrosion length of the pretreated corroded test sample.

[0011] In this invention, the corrosion testing method adapted to the corrosion intensity of passenger vehicles in China operates primarily by inducing corrosion behavior in the test sample of the passenger vehicle to closely resemble actual service conditions through a composite salt system, iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres, and an alternating wet and dry process. After washing with deionized water, wiping with anhydrous ethanol, and drying, the surface soluble impurities, dust, and oil residues of the test sample are reduced. The protective layer on the test surface is damaged after scratching, exposing the substrate or coating to the composite corrosion solution. The shielding of non-evaluation surfaces limits the interference of corrosion in irrelevant areas on the test results. In the base corrosion solution, sodium chloride provides the primary chloride corrosion environment; calcium chloride dihydrate and magnesium chloride hexahydrate are hygroscopic, enhancing salt retention at scratches, edges, and crevices; anhydrous sodium sulfate and sodium nitrate introduce sulfate and nitrate factors; ammonium chloride introduces ammonium salt factors; and sodium bicarbonate buffers the acid-base fluctuations of the composite corrosion solution, maintaining its stability within a weakly acidic to near-neutral range. After iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are added to and dispersed in the base corrosion solution, the silicon-oxygen microsphere framework acts as a microscale deposition carrier. The iron-manganese complex components and sulfate and nitrate components enter the scratch, edge, and crevice areas along with the water film. Salt spray deposition causes the composite corrosion solution to adhere to the sample surface. Wet heat penetration causes the water film and salt to migrate into the scratches and crevices. Hot air drying causes water evaporation and salt concentration and deposition. Room temperature rehumidification causes the hygroscopic salts to reabsorb water and form an electrolyte film. After the above cycle is repeated, undercoating expansion and substrate corrosion occur at the scratches, localized retention corrosion occurs at the edges and crevices, and pitting corrosion and mass loss occur at the exposed metal parts. Finally, the corrosion resistance level of passenger car materials and structures under domestic composite corrosion intensity conditions is reflected by testing the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss, and crevice corrosion length.

[0012] According to a preferred embodiment of the present invention, in step S1, the drying time at 45-55°C is 30-45 minutes.

[0013] According to a preferred embodiment of the present invention, in step S2, the pH is adjusted to 5.2-6.2.

[0014] According to a preferred embodiment of the present invention, in step S3, the temperature of salt spray deposition is 33-37°C, the temperature of wet heat infiltration is 48-52°C, the temperature of hot air drying is 58-62°C, and the temperature of room temperature rehumidification is 23-27°C.

[0015] According to a preferred embodiment of the present invention, in step S4, the drying time is 1-2 hours.

[0016] According to a preferred embodiment of the present invention, the preparation steps of the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres include:

[0017] A1. By weight, add 75-100 parts of anhydrous ethanol and 15-25 parts of deionized water to a reactor and stir at 20-30°C; then add 4-7 parts of ammonia water to obtain an alkaline alcohol aqueous solution; mix 10-15 parts of tetraethyl orthosilicate and 10-20 parts of anhydrous ethanol and add dropwise to the alkaline alcohol aqueous solution, stirring to obtain a silica microsphere dispersion; mix 2-4 parts of 3-aminopropyltriethoxysilane and 8-15 parts of anhydrous ethanol and add dropwise to the silica microsphere dispersion, continue the reaction, and allow to stand for aging to obtain a silica microsphere emulsion with amino complexation sites;

[0018] A2. Add 35-50 parts of deionized water to the reactor, then add 5-8 parts of ferric nitrate nonahydrate, 3-5 parts of manganese sulfate monohydrate, 4-7 parts of citric acid monohydrate, 1-2 parts of anhydrous sodium sulfate, and 2-3 parts of sodium nitrate. Stir at 40-50℃ to obtain a complex precursor liquid. Add the emulsion of silica microspheres with amino complexation sites to the complex precursor liquid, adjust the pH to 3.5-4.5 with ammonia, and react at 55-65℃ to obtain a dispersion of iron-manganese-sulfur-nitrate-silicon complex microsphere precursor.

[0019] A3. Cool the iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion to 40-45℃, add 2-4 parts of ethylene glycol, and stir; adjust the pH to 5.0-5.5, transfer to a reaction vessel, and hydrothermally age at 80-90℃. After cooling, centrifuge to obtain the precipitate; wash the precipitate successively with deionized water and anhydrous ethanol, and vacuum dry to obtain the iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate.

[0020] A4. The iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate was placed in a tube furnace and heated to 160-180℃ under a nitrogen atmosphere; then heated to 260-300℃ and naturally cooled to 20-30℃ to obtain the product; the product was added to 80-120 parts of anhydrous ethanol and 20-40 parts of deionized water, dispersed, ball-milled, centrifuged, dried and sieved.

[0021] In this invention, the preparation mechanism of iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres mainly includes four processes: silicon-oxygen framework formation, amino site introduction, metal complexation loading, and heat treatment stabilization. Anhydrous ethanol and deionized water form a homogeneous alcohol-water medium. Ammonia water makes the system alkaline. Tetraethyl orthosilicate hydrolyzes in this medium to generate silanol structures. These silanol structures then undergo condensation reactions, gradually forming a silicon-oxygen framework and constituting a silicon-oxygen microsphere dispersion. Anhydrous ethanol improves the compatibility between tetraethyl orthosilicate and deionized water, while ammonia water promotes hydrolysis and condensation, resulting in a well-dispersed silicon-oxygen microsphere dispersion. Upon adding 3-aminopropyltriethoxysilane to the silicon-oxygen microsphere dispersion, the alkoxy groups in the 3-aminopropyltriethoxysilane molecule hydrolyze in the alcohol-water medium to generate silanol structures. These silanol structures then undergo condensation reactions with the silanol structures remaining on the surface of the silicon-oxygen microspheres, fixing the amino-containing organosilicon segments onto the surface of the silicon-oxygen microspheres, resulting in a silicon-oxygen microsphere emulsion with amino complexation sites. Ferric nitrate nonahydrate and manganese sulfate monohydrate dissociate in deionized water to form an ionic system containing iron and manganese. The carboxyl and hydroxyl groups in the citric acid monohydrate coordinate with the iron and manganese ions, maintaining the iron ions in a stable dissolved state under weakly acidic conditions and preventing direct hydrolysis to form precipitates. Anhydrous sodium sulfate and sodium nitrate provide sulfate and nitrate sources in the complexation precursor fluid without producing significant side reactions with ferric nitrate nonahydrate, manganese sulfate monohydrate, and citric acid monohydrate. After the silica microsphere emulsion with amino complexation sites is added to the complexation precursor fluid, the amino groups on the microsphere surface are protonated under weakly acidic conditions. These amino groups combine with the complex structures formed by the iron, manganese, and citric acid monohydrate through electrostatic and coordination adsorption, enriching the iron, manganese, sulfur, and nitrate components on the surface and pore regions of the silica microspheres. After adding ethylene glycol to the precursor dispersion of iron-manganese-sulfur-nitrate-silicon complex microspheres, the two hydroxyl groups of ethylene glycol participate in the stabilization and dispersion of the metal complex layer. The hydrothermal aging process causes the complex layer to rearrange on the surface of the silicon-oxygen microspheres and enhances the bonding. After centrifugation, washing and vacuum drying, the intermediate of iron-manganese-sulfur-nitrate-silicon complex microspheres is subjected to staged heat treatment under a nitrogen atmosphere. The residual solvent and adsorbed water are removed first, and the weakly bound organic components are further decomposed and volatilized with increasing temperature. The silicon-oxygen framework and the iron-manganese-sulfur-nitrate complex structure are stably preserved. Finally, after wet ball milling, centrifugation, drying and sieving in anhydrous ethanol and deionized water, the agglomerated structure is broken down to obtain iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres that can be uniformly dispersed in the basic corrosion solution.

[0022] According to a preferred embodiment of the present invention, in step A1, the reaction continues for 4-6 hours.

[0023] According to a preferred embodiment of the present invention, in step A2, the reaction time at 55-65°C is 6-8 hours.

[0024] According to a preferred embodiment of the present invention, in step A3, the hydrothermal aging time at 80-90°C is 8-12 hours.

[0025] According to a preferred embodiment of the present invention, in step A4, the time for heating to 260-300°C is 2-3 hours.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) This invention continuously sets up the processes of washing passenger vehicle test samples with deionized water, wiping with anhydrous ethanol, drying, scratching, masking, weighing, and cyclic corrosion exposure, so that the passenger vehicle test samples form a relatively consistent surface state before the test, reducing the influence of surface dust, oil residue, and corrosion on non-evaluation surfaces on the test results. After the test surface is scratched, the local protective layer is destroyed, and the composite corrosion liquid can be directly applied to the substrate, coating, or connection parts, which facilitates the observation of the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss, and crevice corrosion length, and can reflect the corrosion changes in weak areas such as scratches, edges, and crevices in the actual use of passenger vehicles.

[0028] (2) The basic corrosion solution of this invention is composed of deionized water, sodium chloride, calcium chloride dihydrate, magnesium chloride hexahydrate, anhydrous sodium sulfate, sodium nitrate, ammonium chloride, and sodium bicarbonate. The components are clearly defined, and the preparation process is simple. Sodium chloride provides chloride corrosion conditions, calcium chloride dihydrate and magnesium chloride hexahydrate enhance the hygroscopic and rehydration effects of salt, anhydrous sodium sulfate and sodium nitrate introduce sulfate and nitrate factors, ammonium chloride introduces ammonium salt factors, and sodium bicarbonate buffers the acid-base fluctuations of the composite corrosion solution. The above components work together to enable the composite corrosion solution to cover corrosion factors such as coastal salt, road salt, humid and hot environments, and urban subsidence, which is more in line with the service corrosion characteristics of domestic passenger cars than a single salt spray corrosion solution.

[0029] (3) In this invention, iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are added to the basic corrosion solution. The iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are formed by silicon-oxygen microsphere dispersion, ferric nitrate nonahydrate, manganese sulfate monohydrate, citric acid monohydrate, anhydrous sodium sulfate, sodium nitrate, and ethylene glycol. After being dispersed in the composite corrosion solution, the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres can enter the scratch, edge, and crevice areas with the liquid film, so that the local areas maintain sufficient salt contact and moisture retention. During the salt spray deposition, wet heat penetration, hot air drying, and room temperature rehumidification cycle, the composite corrosion solution undergoes deposition, penetration, concentration, and rewetting processes on the surface of the test sample, which can form multiple evaluation results such as scratch expansion, red rust, edge corrosion, pitting corrosion, mass loss, and crevice corrosion, thereby being used to compare the differences in corrosion intensity of different passenger car materials, coatings, and structures. Detailed Implementation

[0030] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0031] Example 1

[0032] This embodiment provides a corrosion testing method adapted to the corrosion intensity of passenger vehicles in China, including the following steps:

[0033] S1. Hot-dip galvanized steel sheets coated for passenger vehicles were selected as the test samples for passenger vehicles. The sample size was 100mm×150mm×0.8mm, and three parallel samples were set up in each group. The passenger vehicle test samples were washed with deionized water. During washing, 100g of deionized water was used to rinse the test surface and back of each sample. Then, the test surface and back were wiped with a lint-free cloth soaked in anhydrous ethanol. The samples were dried at 50°C for 37.5min to obtain the pretreated passenger vehicle test samples. The test samples were then subjected to further testing. Scratches were prepared on the surface of the vehicle, with a length of 90 mm, a width of 0.5 mm, and a depth reaching the metal substrate. The non-evaluation surfaces were masked with corrosion-resistant tape and epoxy edge sealing material, leaving the scratched area, edge area, and evaluation area of ​​the test surface exposed, thus obtaining the prepared passenger vehicle test sample. The prepared passenger vehicle test sample was weighed and the initial mass was recorded with a weighing accuracy of 0.1 mg. Then, the prepared passenger vehicle test sample was placed in a cyclic corrosion test chamber with the test surface facing upwards and the samples kept from contacting each other.

[0034] S2. Add 1000g of deionized water to a container, then add 10g of sodium chloride, 1.5g of calcium chloride dihydrate, 0.75g of magnesium chloride hexahydrate, 1.15g of anhydrous sodium sulfate, 0.55g of sodium nitrate, 0.35g of ammonium chloride, and 0.55g of sodium bicarbonate in sequence. Stir at 400r / min for 30min at 25°C to obtain the basic etching solution. Add 0.055g of iron-manganese-sulfur-nitrate-silicon complexed etching-promoting microspheres to the basic etching solution, stir at 400r / min for 20min, then ultrasonically disperse for 15min, and adjust the pH to 5.7 to obtain the composite etching solution.

[0035] S3. Add the composite corrosion solution to the storage tank of the cyclic corrosion test chamber, and sequentially subject the prepared passenger vehicle test sample to salt spray deposition, wet heat penetration, hot air drying, and room temperature rehumidification cyclic treatment; wherein, the salt spray deposition temperature is 35°C, the treatment time is 2h, and the spray deposition rate is 1.5mL / (80cm). 2•h); The temperature for wet heat infiltration was 50°C, the treatment time was 6h, and the relative humidity was 95%; the temperature for hot air drying was 60°C, the treatment time was 8h, and the relative humidity was 25%; the temperature for room temperature rehumidification was 25°C, the treatment time was 8h, and the relative humidity was 55%; salt spray deposition, wet heat infiltration, hot air drying, and room temperature rehumidification were considered as one cycle, and a total of 30 cycles were performed to obtain the corroded test sample;

[0036] S4. Remove the corroded test sample and place it at 25°C for 30 minutes. Rinse the surface with deionized water to remove residual salt. Rinse each sample with 100g of deionized water. After rinsing, dry at 50°C for 1.5 hours to obtain the pretreated corroded test sample. Test the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss, and crevice corrosion length of the pretreated corroded test sample. Specifically, the scratch corrosion spread width is measured every 10mm along the scratch length and the average value is taken. The red rust area is calculated as a percentage of the test surface area using image analysis. The edge corrosion width is measured every 10mm along the sample edge and the average value is taken. The pitting depth is determined by surface profile measurement. The mass loss is calculated by the mass difference before and after the test. The crevice corrosion length is measured after cutting open the shielded edge and the flanged simulated area.

[0037] Preparation steps of iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres:

[0038] A1. Add 87.5g of anhydrous ethanol and 20g of deionized water to a reactor equipped with a mechanical stirrer. Stir at 400 rpm for 20 minutes at 25°C until the anhydrous ethanol and deionized water are thoroughly mixed. Then add 5.5g of ammonia water and continue stirring at 400 rpm for 15 minutes to obtain an alkaline alcohol-water solution. Add 12.5g of tetraethyl orthosilicate and 15g of anhydrous ethanol to a clean container and stir at 300 rpm for 10 minutes until thoroughly mixed. Then, add the mixture dropwise to the alkaline alcohol-water solution over 30 minutes using a dropping funnel. During the process, the system temperature was maintained at 25°C and stirred continuously at 400 r / min. After the addition was completed, stirring was continued for 3 h to obtain a silica microsphere dispersion. 3 g of 3-aminopropyltriethoxysilane and 11.5 g of anhydrous ethanol were added to another clean container and stirred at 300 r / min for 10 min to mix evenly. Then, the mixture was added dropwise to the silica microsphere dispersion over 20 min. After the addition was completed, the reaction was continued at 25°C for 5 h. After the reaction was completed, stirring was stopped, and the mixture was allowed to stand at 25°C for 12 h to obtain a silica microsphere emulsion with amino complexation sites.

[0039] A2. Add 42.5g of deionized water to a reactor equipped with a mechanical stirrer, then add 6.5g of ferric nitrate nonahydrate, 4g of manganese sulfate monohydrate, 5.5g of citric acid monohydrate, 1.5g of anhydrous sodium sulfate, and 2.5g of sodium nitrate in sequence. Stir at 400r / min for 40min at 45°C to ensure uniform dispersion of the components and obtain a complex precursor liquid. Add the silica microsphere emulsion with amino complexation sites obtained in step A1 to the complex precursor liquid within 30min, maintaining the temperature at 45°C and stirring at 400r / min during the addition process. After the addition is completed, adjust the pH to 4.0 with ammonia water, then raise the temperature to 60°C and stir at 400r / min for 7h to obtain an iron-manganese-sulfur-nitrate-silica complex microsphere precursor dispersion.

[0040] A3. Cool the iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion obtained in step A2 to 42.5°C, add 3g of ethylene glycol, and stir at 400r / min for 30min. Then adjust the pH to 5.25, transfer it to a polytetrafluoroethylene-lined reactor, filling the reactor to 70% of the liner volume, seal it, and place it in an oven for hydrothermal aging at 85°C for 10h. After hydrothermal aging, allow it to cool naturally to 25°C, transfer the obtained material to a centrifuge tube, centrifuge at 7000r / min for 10min, discard the supernatant, and obtain the precipitate. Wash the precipitate three times with deionized water, adding 50g of deionized water each time and shaking to disperse before centrifugation. Then wash it twice with anhydrous ethanol, adding 50g of anhydrous ethanol each time and shaking to disperse before centrifugation. Vacuum dry the washed precipitate at 60°C and a vacuum degree not exceeding -0.08MPa for 12h to obtain the iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate.

[0041] A4. The iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate obtained in step A3 was evenly spread in a ceramic boat and placed in the constant temperature zone of a tube furnace. It was heated to 170°C for 1.5 h under a nitrogen atmosphere, then heated to 280°C for 2.5 h and naturally cooled to 25°C to obtain the product. The product was added to 100 g of anhydrous ethanol and 30 g of deionized water and stirred at 500 r / min for 20 min for pre-dispersion, followed by ultrasonic dispersion for 30 min. The dispersed material was transferred to a ball mill jar and zirconia balls were used as the ball milling medium with a ball-to-material mass ratio of 6:1. The mixture was ball milled for 3 h. After ball milling, the slurry was removed and centrifuged at 7000 r / min for 10 min. The supernatant was discarded, and the resulting solid was dried at 60°C for 10 h and then sieved through a 300-mesh sieve to obtain the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres.

[0042] Example 2

[0043] The difference between this embodiment and Embodiment 1 is that this embodiment provides a corrosion testing method adapted to the corrosion intensity of passenger vehicles in China, including the following steps:

[0044] S1. Wash the passenger vehicle test sample with deionized water, then wipe it with anhydrous ethanol, and dry it at 45°C for 30 min to obtain the pretreated passenger vehicle test sample; prepare scratches on the test surface of the pretreated passenger vehicle test sample and mask the non-evaluation surface to obtain the prepared passenger vehicle test sample; weigh the prepared passenger vehicle test sample and record the initial mass, and then put it into the cyclic corrosion test chamber;

[0045] S2. Add 990g of deionized water to a container, then add 8.0g of sodium chloride, 1.0g of calcium chloride dihydrate, 0.5g of magnesium chloride hexahydrate, 0.8g of anhydrous sodium sulfate, 0.3g of sodium nitrate, 0.2g of ammonium chloride, and 0.3g of sodium bicarbonate. Stir to obtain a basic etching solution. Add 0.03g of iron-manganese-sulfur-nitrate-silicon complexed etching-promoting microspheres to the basic etching solution, disperse, and adjust the pH to 5.2 to obtain a composite etching solution.

[0046] S3. Add the composite corrosion solution to the cyclic corrosion test chamber and subject the prepared passenger car test sample to salt spray deposition, wet heat penetration, hot air drying and room temperature rehumidification cyclic treatment in sequence. The temperature of salt spray deposition is 33°C, the temperature of wet heat penetration is 48°C, the temperature of hot air drying is 58°C, and the temperature of room temperature rehumidification is 23°C to obtain the corroded test sample.

[0047] S4. Take out the corroded test sample, rinse it with deionized water, and dry it at 45°C for 1 hour to obtain the pretreated corroded test sample; test the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss and crevice corrosion length of the pretreated corroded test sample.

[0048] Preparation steps of iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres:

[0049] A1. Add 75g of anhydrous ethanol and 15g of deionized water to a reactor and stir at 20°C until a homogeneous alcohol-water system is formed. Then add 4g of ammonia water and continue stirring to obtain an alkaline alcohol-water solution. Mix 10g of tetraethyl orthosilicate and 10g of anhydrous ethanol until homogeneous, and then add it dropwise to the alkaline alcohol-water solution while stirring to obtain a silica microsphere dispersion. Mix 2g of 3-aminopropyltriethoxysilane and 8g of anhydrous ethanol until homogeneous, and then add it dropwise to the silica microsphere dispersion. Continue the reaction for 4 hours. After the reaction is completed, allow it to stand and age to obtain a silica microsphere emulsion with amino complexation sites.

[0050] A2. Add 35g of deionized water to the reactor, then add 5g of ferric nitrate nonahydrate, 3g of manganese sulfate monohydrate, 4g of citric acid monohydrate, 1g of anhydrous sodium sulfate, and 2g of sodium nitrate. Stir at 40°C until all components are evenly dispersed to obtain a complex precursor liquid. Add the silica microsphere emulsion with amino complexation sites obtained in step A1 to the complex precursor liquid, adjust the pH to 3.5 with ammonia, and heat to 55°C for 6 hours to obtain an iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion.

[0051] A3. Cool the iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion obtained in step A2 to 40°C, add 2g of ethylene glycol, and stir until uniformly dispersed; adjust the pH to 5.0, transfer to a reaction vessel, and hydrothermally age at 80°C for 8 hours. After cooling, centrifuge to obtain the precipitate; wash the precipitate successively with deionized water and anhydrous ethanol, and vacuum dry to obtain the iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate.

[0052] A4. The iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate obtained in step A3 was placed in a tube furnace and heated to 160°C under a nitrogen atmosphere; then heated to 260°C for 2 hours and naturally cooled to 20°C to obtain the product; the product was added to 80g of anhydrous ethanol and 20g of deionized water, dispersed, ball-milled, centrifuged, dried, and sieved to obtain iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres.

[0053] Example 3

[0054] The difference between this embodiment and Embodiment 1 is that this embodiment provides a corrosion testing method adapted to the corrosion intensity of passenger vehicles in China, including the following steps:

[0055] S1. Wash the passenger vehicle test sample with deionized water, then wipe it with anhydrous ethanol, and dry it at 55°C for 45 min to obtain the pretreated passenger vehicle test sample; prepare scratches on the test surface of the pretreated passenger vehicle test sample and mask the non-evaluation surface to obtain the prepared passenger vehicle test sample; weigh the prepared passenger vehicle test sample and record the initial mass, and then put it into the cyclic corrosion test chamber;

[0056] S2. Add 1010g of deionized water to a container, then add 12.0g of sodium chloride, 2.0g of calcium chloride dihydrate, 1.0g of magnesium chloride hexahydrate, 1.5g of anhydrous sodium sulfate, 0.8g of sodium nitrate, 0.5g of ammonium chloride, and 0.8g of sodium bicarbonate. Stir to obtain the basic etching solution. Add 0.08g of iron-manganese-sulfur-nitrate-silicon complexed etching-promoting microspheres to the basic etching solution, disperse, and adjust the pH to 6.2 to obtain the composite etching solution.

[0057] S3. Add the composite corrosion solution to the cyclic corrosion test chamber and sequentially perform salt spray deposition, wet heat penetration, hot air drying and room temperature rehumidification cyclic treatment on the prepared passenger car test sample. The temperature of salt spray deposition is 37°C, the temperature of wet heat penetration is 52°C, the temperature of hot air drying is 62°C, and the temperature of room temperature rehumidification is 27°C to obtain the corroded test sample.

[0058] S4. Take out the corroded test sample, rinse it with deionized water, and dry it at 55°C for 2 hours to obtain the pretreated corroded test sample; test the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss and crevice corrosion length of the pretreated corroded test sample.

[0059] Preparation steps of iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres:

[0060] A1. Add 100g of anhydrous ethanol and 25g of deionized water to a reactor and stir at 30°C until a homogeneous alcohol-water system is formed. Then add 7g of ammonia water and continue stirring to obtain an alkaline alcohol-water solution. Mix 15g of tetraethyl orthosilicate and 20g of anhydrous ethanol until homogeneous, and then add it dropwise to the alkaline alcohol-water solution while stirring to obtain a silica microsphere dispersion. Mix 4g of 3-aminopropyltriethoxysilane and 15g of anhydrous ethanol until homogeneous, and then add it dropwise to the silica microsphere dispersion. Continue the reaction for 6 hours. After the reaction is completed, allow it to stand and age to obtain a silica microsphere emulsion with amino complexation sites.

[0061] A2. Add 50g of deionized water to the reactor, then add 8g of ferric nitrate nonahydrate, 5g of manganese sulfate monohydrate, 7g of citric acid monohydrate, 2g of anhydrous sodium sulfate, and 3g of sodium nitrate. Stir at 50°C until all components are evenly dispersed to obtain a complex precursor liquid. Add the silica microsphere emulsion with amino complexation sites obtained in step A1 to the complex precursor liquid, adjust the pH to 4.5 with ammonia, and heat to 65°C for 8 hours to obtain an iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion.

[0062] A3. Cool the iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion obtained in step A2 to 45°C, add 4g of ethylene glycol, and stir until uniformly dispersed; adjust the pH to 5.5, transfer to a reaction vessel, and hydrothermally age at 90°C for 12h. Cool, centrifuge to obtain the precipitate; wash the precipitate with deionized water and anhydrous ethanol in sequence, and vacuum dry to obtain the iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate.

[0063] A4. The iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate obtained in step A3 was placed in a tube furnace and heated to 180°C under a nitrogen atmosphere; then heated to 300°C for 3 hours and naturally cooled to 30°C to obtain the product; the product was added to 120g of anhydrous ethanol and 40g of deionized water, dispersed, ball-milled, centrifuged, dried, and sieved to obtain iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that 0.055g of iron-manganese-sulfur-nitrate-silicon complexed corrosion-promoting microspheres are not added in step S2, while the rest is the same as in Example 1.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that in step S2, 0.055g of iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are replaced with 0.055g of silicon-oxygen microspheres, and the rest is the same as in Example 1;

[0068] The silica microspheres were prepared as follows: 87.5 g of anhydrous ethanol and 20 g of deionized water were added to a reactor equipped with a mechanical stirrer and stirred at 400 r / min for 20 min at 25°C to ensure uniform mixing of the anhydrous ethanol and deionized water; then 5.5 g of ammonia water was added, and stirring was continued at 400 r / min for 15 min to obtain an alkaline alcohol aqueous solution; 12.5 g of tetraethyl orthosilicate and 15 g of anhydrous ethanol were added to a clean container and stirred at 300 r / min for 10 min to ensure uniform mixing. Then, the mixture was added dropwise to the alkaline alcohol aqueous solution over 30 min using a dropping funnel. The system temperature was maintained at 25°C, and the mixture was continuously stirred at 400 r / min. After the addition was completed, stirring was continued for 3 h to obtain a silica microsphere dispersion. The silica microsphere dispersion was centrifuged at 7000 r / min for 10 min, and the supernatant was discarded to obtain the precipitate. The precipitate was washed three times with deionized water, each time with 50 g of deionized water added and the mixture was shaken and dispersed before centrifugation. The precipitate was then washed twice with anhydrous ethanol, each time with 50 g of anhydrous ethanol added and the mixture was shaken and dispersed before centrifugation. The washed precipitate was vacuum dried at 60°C and a vacuum degree not exceeding -0.08 MPa for 12 h to obtain silica microspheres.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are not prepared. In step S2, 0.055g of iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres are replaced with 0.0179g of ferric nitrate nonahydrate, 0.0110g of manganese sulfate monohydrate, 0.0151g of citric acid monohydrate, 0.0041g of anhydrous sodium sulfate and 0.0069g of sodium nitrate. The rest is the same as in Example 1.

[0071] In accordance with national and industry standard testing specifications, a series of standardized tests were conducted on the corrosion test methods for the corrosion intensity of passenger vehicles adapted to domestic conditions as described in Examples 1-3 and Comparative Examples 1-3.

[0072] Performance tests were conducted on the pretreated and corroded test samples obtained from Examples 1-3 and Comparative Examples 1-3, respectively. Each group had n=3 parallel samples, and the average value of all test results was taken as n=3.

[0073] The test method for scratch corrosion spread width / mm is as follows: Fix the sample with the test surface facing up on the platform. After removing the loose corrosion products on the surface of the scratch area, select one measuring point every 10mm along the scratch length direction, starting from 10mm from the end of the scratch. Use a measuring tool with a reading accuracy of 0.01mm to measure the total width of corrosion spread on both sides of the scratch. At least 8 measuring points are measured for each sample. Take the average value of all measuring points of the same sample as the scratch corrosion spread width of the sample, and then take the average value of n=3.

[0074] The test method for red rust area / % is as follows: Place the dried sample under a uniform light source, keep the test surface parallel to the camera lens, acquire the image of the test surface, use image analysis to identify the red rust area and the effective evaluation area of ​​the test surface, calculate the proportion of the red rust area to the effective evaluation area of ​​the test surface, measure each sample once, and take the average value of n=3.

[0075] The test method for edge corrosion width / mm is as follows: Select one measuring point every 10mm along the evaluation edge direction of the sample, and use a measuring tool with a reading accuracy of 0.01mm to measure the maximum vertical distance of corrosion spreading inward from the edge. At least 10 measuring points are measured for each sample. Take the average value of all measuring points of the same sample as the edge corrosion width of the sample, and then take the average value of n=3.

[0076] The test method for pitting depth / μm is as follows: Select an area with obvious pitting on the test surface of the sample, rinse and dry it with deionized water, remove loose corrosion products, and use a surface profile measuring device to measure the height difference from the bottom of the pit to the adjacent uncorroded reference surface. Five pits are selected for each sample for measurement, and the maximum value is taken as the pitting depth of the sample. Then, the average value of n=3 is taken.

[0077] Mass loss / (mg / cm) 2 The test method is as follows: before the test, record the initial mass of the passenger car test sample. After the test, rinse, dry and remove the loose corrosion products of the corroded test sample and weigh it again. The weighing accuracy is 0.1 mg. Calculate the mass loss per unit area by dividing the mass difference before and after the test by the effective exposed area of ​​the sample. Calculate once for each sample and take the average value of n=3.

[0078] The test method for crevice corrosion length / mm is as follows: Open the shielded edge or flanged simulated area, observe the continuous corrosion expansion traces along the crevice direction, and use a measuring tool with a reading accuracy of 0.01mm to determine the length of the continuous corrosion area inside the crevice. Select 3 crevice evaluation positions for each sample, take the average value as the crevice corrosion length of the sample, and then take the average value of n=3.

[0079] The performance test data above are shown in Table 1.

[0080] Table 1: Performance Test Results

[0081]

[0082] As can be seen from the above, Examples 1-3 can more fully induce the passenger vehicle test samples to produce evaluable composite corrosion behavior compared with Comparative Examples 1-3, thereby solving the problems of insufficient corrosion intensity, insignificant local corrosion, and difficulty in distinguishing differences between different materials or structures when using existing single corrosive liquids or lacking effective corrosion-promoting and retention components.

[0083] Specifically, the scratch corrosion spread width of Example 1 was 2.42 mm, which was significantly higher than that of Comparative Example 1 (0.86 mm), Comparative Example 2 (1.14 mm), and Comparative Example 3 (1.69 mm). This indicates that after adding iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres, the composite corrosion solution can act more effectively on the scratch area, promote corrosion spread at the scratch, and make the corrosion intensity evaluation of the weak scratch area more comprehensive.

[0084] The red rust area of ​​Example 1 was 15.6%, which was higher than that of Comparative Example 1 (4.5%), Comparative Example 2 (6.7%), and Comparative Example 3 (10.2%). The edge corrosion width was 1.28 mm, which was higher than that of Comparative Example 1 (0.42 mm), Comparative Example 2 (0.58 mm), and Comparative Example 3 (0.91 mm). This indicates that the present invention, through the combination of sodium chloride, calcium chloride dihydrate, magnesium chloride hexahydrate, anhydrous sodium sulfate, sodium nitrate, ammonium chloride, sodium bicarbonate, and iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres, can enhance the formation of red rust and the corrosion performance of the edge area, and improve the problem of insufficient reflection of edge corrosion and red rust changes in traditional corrosion tests.

[0085] The pitting depth in Example 1 was 72 μm, and the mass loss was 8.6 mg / cm. 2 The crevice corrosion length was 5.8 mm, both higher than the 28 μm and 3.2 mg / cm² of Comparative Example 1. 2 The thickness was 1.8 mm, which is also higher than that of Comparative Example 2 (36 μm, 4.1 mg / cm). 2 2.5 mm and 54 μm and 6.3 mg / cm² of Comparative Example 3 2The thickness of 3.9 mm indicates that the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres do not simply provide solid particles or soluble metal salt components. Instead, they rely on the combined effect of the silicon-oxygen microsphere carrier, the iron-manganese complex component, and the sulfate and nitrate components to enable the corrosive medium to have more sufficient contact and retention in local areas such as scratches, edges, and crevices.

[0086] In Example 2, the scratch corrosion spread width was 2.06 mm, the red rust area was 12.8%, the edge corrosion width was 1.05 mm, the pitting depth was 61 μm, and the mass loss was 7.4 mg / cm². 2 The crevice corrosion length was 4.9 mm, which was still significantly higher than that of comparative examples 1-3, indicating that even under low corrosion intensity formulation and process conditions, the present invention can still form a stable and measurable corrosion response.

[0087] In Example 3, the scratch corrosion spread width reached 2.79 mm, the red rust area reached 18.4%, the edge corrosion width reached 1.56 mm, the pitting depth reached 86 μm, and the mass loss reached 10.2 mg / cm³. 2 The crevice corrosion length reached 6.7 mm, indicating that the corrosion intensity increased with the concentration of the composite corrosion solution, the amount of iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres, and the increase in cyclic conditions, demonstrating that the present invention has a good ability to distinguish corrosion intensity.

[0088] Comparative Example 1, which did not contain iron, manganese, sulfur, nitrate, and silicon complexed corrosion-promoting microspheres, had the lowest corrosion indexes, indicating that ordinary basic corrosion solutions are difficult to fully simulate the corrosion intensity under the complex service environment of passenger vehicles.

[0089] Comparative Example 2 used only silicon-oxygen microspheres to replace the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres. Although the corrosion index was slightly increased compared to Comparative Example 1, it was still significantly lower than that of Examples 1-3, indicating that the simple silicon-oxygen carrier cannot achieve the corrosion-promoting and retention effects of the present invention.

[0090] Comparative Example 3 directly added ferric nitrate nonahydrate, manganese sulfate monohydrate, citric acid monohydrate, anhydrous sodium sulfate, and sodium nitrate. Its corrosion index was higher than that of Comparative Examples 1 and 2 but lower than that of Examples 1-3. This indicates that although the direct addition of soluble components to the basic corrosion solution can improve the corrosion intensity, it lacks the surface fixation and local retention effect of the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres, making it difficult to form a continuous and stable composite corrosion environment at scratches, edges, and crevices.

[0091] Therefore, this invention solves the technical problems of insufficient adaptability of existing corrosion testing methods to the complex corrosion environment of domestic passenger vehicles, weak corrosion intensity response, insufficient evaluation of local corrosion, and insufficient differentiation of different corrosion-sensitive parts by means of the synergistic effect of composite corrosion liquid and iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres.

Claims

1. A corrosion testing method adapted to the corrosion intensity of passenger vehicles in China, characterized in that, Includes the following steps: S1. Wash the passenger vehicle test sample with deionized water, wipe it with anhydrous ethanol, and dry it at 45-55℃ to obtain the pretreated passenger vehicle test sample. Scratches were prepared on the test surface of the pretreated passenger vehicle test sample, and the non-evaluation surface was masked to obtain the prepared passenger vehicle test sample; the prepared passenger vehicle test sample was weighed and the initial mass was recorded, and then placed in a cyclic corrosion test chamber. S2. By weight, add 990-1010 parts of deionized water to a container, then add 8.0-12.0 parts of sodium chloride, 1.0-2.0 parts of calcium chloride dihydrate, 0.5-1.0 parts of magnesium chloride hexahydrate, 0.8-1.5 parts of anhydrous sodium sulfate, 0.3-0.8 parts of sodium nitrate, 0.2-0.5 parts of ammonium chloride, and 0.3-0.8 parts of sodium bicarbonate. Stir to obtain a basic etching solution. Add 0.03-0.08 parts of iron-manganese-sulfur-nitrate-silicon complexed etching-promoting microspheres to the basic etching solution, disperse, and adjust the pH to obtain a composite etching solution. S3. Add the composite corrosion solution to the cyclic corrosion test chamber and sequentially perform salt spray deposition, wet heat penetration, hot air drying and room temperature rehumidification cycle treatment on the prepared passenger car test sample to obtain the corroded test sample. S4. Take out the corroded test sample, rinse it with deionized water, and dry it to obtain the pretreated corroded test sample; test the scratch corrosion spread width, red rust area, edge corrosion width, pitting depth, mass loss and crevice corrosion length of the pretreated corroded test sample. The preparation steps of the iron-manganese-sulfur-nitrate-silicon complex corrosion-promoting microspheres include: A1. By weight, add 75-100 parts of anhydrous ethanol and 15-25 parts of deionized water to a reactor and stir at 20-30°C; then add 4-7 parts of ammonia water to obtain an alkaline alcohol aqueous solution; mix 10-15 parts of tetraethyl orthosilicate and 10-20 parts of anhydrous ethanol and add dropwise to the alkaline alcohol aqueous solution, stirring to obtain a silica microsphere dispersion; mix 2-4 parts of 3-aminopropyltriethoxysilane and 8-15 parts of anhydrous ethanol and add dropwise to the silica microsphere dispersion, continue the reaction, and allow to stand for aging to obtain a silica microsphere emulsion with amino complexation sites; A2. Add 35-50 parts of deionized water to the reactor, then add 5-8 parts of ferric nitrate nonahydrate, 3-5 parts of manganese sulfate monohydrate, 4-7 parts of citric acid monohydrate, 1-2 parts of anhydrous sodium sulfate, and 2-3 parts of sodium nitrate. Stir at 40-50℃ to obtain a complex precursor liquid. Add the emulsion of silica microspheres with amino complexation sites to the complex precursor liquid, adjust the pH to 3.5-4.5 with ammonia, and react at 55-65℃ to obtain a dispersion of iron-manganese-sulfur-nitrate-silicon complex microsphere precursor. A3. Cool the iron-manganese-sulfur-nitrate-silicon complex microsphere precursor dispersion to 40-45℃, add 2-4 parts of ethylene glycol, and stir; adjust the pH to 5.0-5.5, transfer to a reaction vessel, and hydrothermally age at 80-90℃. After cooling, centrifuge to obtain the precipitate; wash the precipitate successively with deionized water and anhydrous ethanol, and vacuum dry to obtain the iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate. A4. The iron-manganese-sulfur-nitrate-silicon complex microsphere intermediate was placed in a tube furnace and heated to 160-180℃ under a nitrogen atmosphere; then heated to 260-300℃ and naturally cooled to 20-30℃ to obtain the product; the product was added to 80-120 parts of anhydrous ethanol and 20-40 parts of deionized water, dispersed, ball-milled, centrifuged, dried and sieved.

2. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step S1, the drying time at 45-55℃ is 30-45 minutes.

3. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step S2, adjust the pH to 5.2-6.

2.

4. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step S3, the temperature for salt spray deposition is 33-37℃, the temperature for wet heat infiltration is 48-52℃, the temperature for hot air drying is 58-62℃, and the temperature for room temperature rehumidification is 23-27℃.

5. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step S4, the drying time is 1-2 hours.

6. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step A1, the reaction continues for 4-6 hours.

7. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards as described in claim 1, characterized in that, In step A2, the reaction time is 6-8 hours after heating to 55-65℃.

8. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards according to claim 1, characterized in that, In step A3, the hydrothermal aging time at 80-90℃ is 8-12 hours.

9. The corrosion test method for assessing corrosion intensity of passenger vehicles adapted to domestic standards according to claim 1, characterized in that, In step A4, the temperature is raised to 260-300℃ and the treatment time is 2-3 hours.

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