Corrosion mud and methods of making and using the same

Abstract

The application provides a kind of corrosion mud and its preparation method and application, wherein the corrosion mud includes kaolin 80-100 parts by weight, iron source 10-60 parts by weight, calcium source 1-10 parts by weight; the pH of the corrosion mud is 4.5-6.6. The application forms the corrosion mud by combining kaolin, iron source and calcium source, the iron source in the corrosion mud can fully contact with the protective coating on the surface of the workpiece to form a primary cell reaction to accelerate the corrosion of the coating on the surface of the workpiece. The corrosion mud can effectively simulate the corrosion of the coating on the surface of the workpiece by the snow melting agent in snow, which is consistent with the actual corrosion environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of component performance testing, in particular to a corrosion mud and a preparation method and application thereof. BACKGROUND

[0002] In the cold northern region, due to the regional characteristics, it often snows in winter, and the heavy snow will cover the road surface and affect the road traffic. In order to effectively remove the snow on the road surface, it is usually necessary to spray snow-melting agent on the road surface to promote the rapid melting of the accumulated snow on the road surface.

[0003] However, these snow-melting agents sprayed on the road surface have great corrosiveness, which may have certain influence on the components of the vehicle, especially the corrosion resistance of the chassis components of the vehicle. The snow-melting agent can cause white spots on the plating layer of the chassis components of the vehicle.

[0004] In order to study the corrosion performance of the snow-melting agent on the components in the actual use state, so as to facilitate the evaluation and improvement of the corrosion resistance of the components, it is necessary to develop a method for simulating the corrosion of the snow-melting agent in the snow under cold conditions on the components, so as to quickly and accurately judge the corrosion resistance of the plating layer on the components to the snow-melting agent. SUMMARY

[0005] Therefore, it is necessary to provide a corrosion mud and a preparation method and application thereof, which can simulate the snow-melting agent in the snow under cold conditions, and quickly and accurately judge the corrosion resistance of the plating layer on the components to the snow-melting agent under cold conditions.

[0006] According to one aspect of the present application, a corrosion mud is provided, which comprises, in terms of weight fraction: 80-100 parts of kaolin, 10-60 parts of iron source, and 1-10 parts of calcium source.

[0007] In some embodiments, the corrosion mud comprises, in terms of weight fraction: 85-95 parts of kaolin, 15-50 parts of iron source, and 3-10 parts of calcium source.

[0008] In some embodiments, the corrosion mud comprises, in terms of weight fraction: 89-90 parts of kaolin, 19-50 parts of iron source, and 5-10 parts of calcium source.

[0009] In some embodiments, the iron source is one or both of iron powder and ferroferric oxide.

[0010] In some embodiments, the iron source is iron powder and ferroferric oxide, and the mass ratio of the iron powder to the ferroferric oxide is (1-4):1.

[0011] In some embodiments, the calcium source is one or more of calcium carbonate, calcium sulfate, calcium nitrate, and calcium chloride.

[0012] According to another aspect of the present application, there is provided a method for preparing the corrosion mud as described above, comprising the steps of:

[0013] providing raw materials for each component of the corrosion mud as described above according to the present application; and

[0014] mixing the components, performing a first grinding, adding an acid to adjust the pH to 4.5-6.6, drying, and performing a second grinding to obtain the corrosion mud.

[0015] In some embodiments, the acid is one or more of hydrochloric acid, dilute sulfuric acid, and glacial acetic acid.

[0016] In some embodiments, the first grinding and the second grinding are independently for 1-3 hours.

[0017] In some embodiments, the drying temperature is 25-35°C, and the drying time is 20-28 hours.

[0018] According to another aspect of the present application, there is provided a method for corrosion testing of a coating layer on a surface of a workpiece, comprising the steps of:

[0019] striking the surface of the workpiece with chilled cast iron pellets;

[0020] uniformly spreading the corrosion mud as described above according to the present application or the corrosion mud prepared by the method as described above according to the present application on the surface of the workpiece;

[0021] placing the workpiece with the corrosion mud on the surface into a salt spray chamber for salt spray corrosion for 6-10 hours;

[0022] placing the workpiece after the salt spray corrosion into a temperature and humidity control chamber for treatment, wherein the temperature in the chamber is 25-55°C, the humidity is 40-50% RH, and the treatment time is 168-288 hours;

[0023] removing the corrosion mud on the surface of the workpiece.

[0024] In some embodiments, the method for corrosion testing further comprises:

[0025] measuring the weight of the workpiece after striking the surface of the workpiece as W1;

[0026] measuring the spreading area of the corrosion mud on the surface of the workpiece as S after spreading the corrosion mud on the surface of the workpiece;

[0027] After the corrosion mud on the surface of the workpiece is removed, the weight of the workpiece is measured and recorded as W2, and the corrosion amount per unit area of the workpiece A is calculated, wherein A=(W1-W2) / S.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The present application uses kaolin, iron source and calcium source to form the corrosion mud, the iron source in the corrosion mud can fully contact with the protective coating on the surface of the workpiece to form a galvanic cell reaction to accelerate the corrosion of the coating on the surface of the workpiece; the kaolin and calcium source can simulate the main components of the road soil, and the combination of the iron source can well simulate the actual use environment of the snow melting agent. The corrosion mud can effectively simulate the corrosion of the snow melting agent in the snow on the coating on the surface of the workpiece, which is consistent with the actual corrosion environment;

[0030] Further, the present application preferably uses iron powder and ferroferric oxide as the iron source in the corrosion mud, and the iron, divalent iron ions and trivalent iron ions exist in the acidic corrosion mud at the same time, which can better form a galvanic cell with the protective coating on the surface of the workpiece, and is conducive to accelerating the simulation corrosion speed of the coating on the surface of the workpiece; at the same time, the corrosion mud is acidic, which can more easily corrode the coating on the surface of the workpiece in the later stage of corrosion, thereby further accelerating the simulation corrosion effect;

[0031] In addition, in the corrosion test method of the present application, the cold hardening cast iron granules are used to pre-impact the surface of the workpiece, which can simulate the impact of small stones on the workpiece in the actual road conditions, improve the roughness of the surface of the workpiece, and make the corrosion mud more easily adhere to the surface of the workpiece, thereby increasing the simulation corrosion speed;

[0032] The corrosion test method of the present application measures the weight of the workpiece after impacting the surface of the workpiece; measures the laying area after laying the corrosion mud on the surface of the workpiece; measures the weight of the workpiece after removing the corrosion mud on the surface of the workpiece, and calculates the corrosion amount per unit area of the workpiece, so as to quantitatively analyze the corrosion condition of the workpiece. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The alternating current impedance spectrum (EIS) of the vehicle parts in Example 1 after being placed in the temperature and humidity control box for 0h, 96h and 288h;

[0034] Figure 2 The corrosion state photos of the surface of the vehicle parts after the corrosion test on the vehicle parts in Example 1;

[0035] Figure 3 The alternating current impedance spectrum (EIS) of the vehicle parts in Example 2 after being placed in the temperature and humidity control box for 0h, 96h, 288h and 456h;

[0036] Figure 4 Photographs of the corrosion state of the surface of the vehicle parts after the corrosion test on the vehicle parts in Example 2;

[0037] Figure 5 EIS of the vehicle parts after being put into the temperature and humidity control box for 0 h, 48 h, 96 h and 168 h in Example 3;

[0038] Figure 6 Photographs of the corrosion state of the surface of the vehicle parts after the corrosion test on the vehicle parts in Example 3;

[0039] Figure 7 EIS of the vehicle parts after being put into the temperature and humidity control box for 0 h, 96 h and 288 h in Example 4;

[0040] Figure 8 Photographs of the corrosion state of the surface of the vehicle parts after the corrosion test on the vehicle parts in Example 4;

[0041] Figure 9 Photographs of the corrosion state of the surface of the vehicle parts after the corrosion test on the vehicle parts in Example 5;

[0042] Figure 10 EIS of the vehicle parts after being put into the temperature and humidity control box for 0 h, 96 h and 288 h in Comparative Example 1;

[0043] Figure 11 EIS of the vehicle parts after being put into the temperature and humidity control box for 0 h, 48 h, 96 h and 168 h in Comparative Example 2. DETAILED DESCRIPTION

[0044] In order to make the above objectives, features and advantages of the present application more apparent, a detailed description of the specific embodiments of the present application will be given. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application. The specific embodiments of the present application are described below.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise expressly defined herein, all

[0046] Some embodiments of the present application provide a kind of corrosion mud, the corrosion mud includes the following components according to weight fraction: 80-100 parts of kaolin clay; 10-60 parts of iron source; 1-10 parts of calcium source; And the pH of the corrosion mud is 4.5-6.6.

[0047] The present application can be combined with the specific ratio of kaolin clay, iron source and calcium source to form corrosion mud, the iron source in the corrosion mud can be in full contact with the protective coating on the surface of the workpiece, form a primary cell reaction to accelerate the corrosion of the coating on the surface of the workpiece; Kaolin clay and calcium source can simulate the main components of the road soil, which can be combined with the iron source to simulate the actual use environment of the snow melting agent. At the same time, the corrosion mud is acidic, so that the corrosion mud can more easily corrode the coating on the surface of the workpiece in the later stage of corrosion, thereby further accelerating the effect of simulated corrosion. The corrosion mud can effectively simulate the corrosion of the snow melting agent in the snow on the coating of the workpiece, and can well match the actual corrosion environment of the workpiece.

[0048] Specifically, in some embodiments, the iron source in the corrosion mud can be one or both of iron powder and ferroferric oxide. In other words, the iron source in the corrosion mud can be iron powder, ferroferric oxide, or a mixture of iron powder and ferroferric oxide.

[0049] In some embodiments, the iron source in the corrosion mud is iron powder and ferroferric oxide, and the mass ratio of iron powder to ferroferric oxide in the corrosion mud is (1-4):1. Using the above-mentioned ratio of iron powder and ferroferric oxide as the iron source, iron, divalent iron ions and trivalent iron ions can exist in the corrosion mud under acidic conditions, which can better form a primary cell with the protective coating on the surface of the workpiece, and is conducive to accelerating the simulated corrosion speed of the coating on the surface of the workpiece.

[0050] In some embodiments, the corrosion mud includes the following components according to weight fraction: 80-100 parts of kaolin clay; 10-60 parts of iron source; 1-10 parts of calcium source. Further preferably, the corrosion mud includes: 89-90 parts of kaolin clay, 19-50 parts of iron source, and 5-10 parts of calcium source by weight. Using the above-mentioned component ratio of the corrosion mud, the corrosion of the snow melting agent in the snow on the coating of the workpiece can be better simulated.

[0051] In some embodiments, the calcium source in the corrosion mud is one or more of calcium carbonate, calcium sulfate, calcium nitrate and calcium chloride.

[0052] Some embodiments of the present application also provide a preparation method of the above-mentioned corrosion mud, which includes the following steps S100 and S200.

[0053] Step S100: provide raw materials according to the components of the corrosion mud described above.

[0054] Specifically, the formula of the corrosion mud according to the present application provides kaolin, an iron source and a calcium source. The iron source can be one or both of iron powder and ferroferric oxide; the calcium source can be one or more of calcium carbonate, calcium sulfate, calcium nitrate and calcium chloride.

[0055] Step S200: The above-mentioned kaolin, iron source and calcium source of the corrosion mud are mixed according to the formula, and then are subjected to first grinding, and then an acid is added to adjust the pH to 4.5-6.6, and then the mixture is dried and subjected to second grinding to obtain the corrosion mud according to the present application.

[0056] The acid used can be a common organic acid or inorganic acid such as dilute hydrochloric acid, dilute sulfuric acid and glacial acetic acid.

[0057] Specifically, the kaolin, iron source and calcium source are first added to a grinding machine according to the formula, and are ground for 1-3 hours to make the components reach a suitable particle size and be uniformly mixed; then the acid is slowly poured into the ground dry powder in a fume hood while stirring and forming a mud, and the mud is measured by pH paper until the pH of the mud is 4.5-6.6; then the mud is dried in a drying oven at 25-35°C for 20-28 hours; and then the dried mud is put into a grinding machine and is fully ground and stirred for 1-3 hours to obtain the corrosion mud according to the present application.

[0058] Some embodiments of the present application also provide a corrosion test method for a coating layer on a surface of a workpiece, which includes the following steps S100-S500.

[0059] Step S100: The surface of the workpiece is struck by cold hard cast iron pellets.

[0060] Before the corrosion test of the workpiece (such as a vehicle part), the surface of the workpiece is first struck by cold hard cast iron pellets, which can simulate the striking of the workpiece by small stones in actual road conditions, increase the roughness of the surface of the workpiece, and make the corrosion mud more easily adhere to the surface of the workpiece, thereby increasing the speed of simulated corrosion.

[0061] Specifically, the surface of the workpiece can be struck by cold hard cast iron pellets of GH-K series with a particle size of 4-5 mm at a pressure of about 100 Kpa to damage the coating layer on the surface of the workpiece, thereby increasing the roughness of the surface of the workpiece, making the visible roughness of the surface of the workpiece be 25-50 μm, and making the medium more easily adhere to the surface of the workpiece.

[0062] Step S200: uniformly spread the above-mentioned corrosion mud of the present application or the corrosion mud prepared by the above-mentioned preparation method of the present application on the surface of the workpiece, so as to form a uniform layer of the corrosion mud on the surface of the workpiece. The thickness of the spread of the corrosion mud can be set according to the actual situation.

[0063] Step S300: place the workpiece with the surface spread with the corrosion mud into a salt spray chamber for salt spray corrosion for 6h-10h.

[0064] Specifically, the workpiece with the surface spread with the corrosion mud can be placed into a salt spray chamber, and the workpiece can be subjected to salt spray corrosion by using the GB / T 10125-2012 (NSS) method.

[0065] Step S400: after the workpiece is subjected to salt spray corrosion, place the workpiece into a temperature and humidity control chamber for treatment, control the temperature in the temperature and humidity control chamber at 25℃-55℃, control the humidity at 40%RH-50%RH, and control the treatment time at 168h-288h.

[0066] After the workpiece is placed into the temperature and humidity control chamber and treated under the above-mentioned temperature and humidity conditions for a predetermined time, the plating layer on the surface of the workpiece can be well corroded, and the corrosion condition of the plating layer on the surface of the workpiece caused by the snow-melting agent can be quickly simulated.

[0067] Step S500: after the temperature and humidity treatment is completed, take out the workpiece from the temperature and humidity control chamber, then wash the corrosion mud on the surface of the workpiece and dry, and observe the change of the protective plating layer on the surface of the workpiece, so that the corrosion effect of the corrosion mud on the plating layer on the surface of the workpiece can be directly observed.

[0068] Further, in the above-mentioned step S100, after the surface of the workpiece is struck by the chilled cast iron pellets, the weight of the workpiece is measured and recorded as W1; in the above-mentioned step S200, after the corrosion mud is spread on the surface of the workpiece, the spread area of the corrosion mud on the surface of the workpiece is measured and recorded as S; in the above-mentioned step S500, after the corrosion mud on the surface of the workpiece is removed, the weight of the workpiece is measured again and recorded as W2; then the corrosion amount A of the workpiece per unit area is calculated, wherein A=(W1-W2) / S.

[0069] By using the above-mentioned method, the change of the workpiece before and after the corrosion test by the corrosion mud can be quantitatively analyzed, and the rapid corrosion of the protective plating layer on the surface of the workpiece caused by the corrosion mud under cold conditions can be accurately simulated.

[0070] The present application will be further described below in combination with specific examples and comparative examples, but should not be understood as limiting the protection scope of the present application.

[0071] Example 1:

[0072] Preparation of corrosive sludge:

[0073] Add 90g of kaolin, 25g of iron powder, 25g of ferric oxide, and 10g of calcium carbonate to a grinder and grind and stir evenly for 2 hours to ensure that each component reaches a suitable particle size and is evenly mixed. In a fume hood, slowly pour dilute hydrochloric acid into the ground dry powder while stirring to form a mud-like consistency. Measure the pH of the mud using pH test paper until the pH is between 4.5 and 6.6. Then, dry the mud in a drying oven at 30°C for 24 hours. Finally, put the dried mud into a grinder and grind and stir thoroughly for 2 hours to obtain corroded mud.

[0074] Corrosion test:

[0075] Vehicle parts with protective coatings on their surfaces were used as workpieces for corrosion testing. GH-K series chilled cast iron granules with dimensions of 4mm–5mm were used to impact the vehicle parts under a pressure of 100KPa, damaging the protective coating and simulating the impact of small stones on the workpiece to increase its surface roughness. The weight of the part was measured as W1.

[0076] Accurately weigh 5g of the above-mentioned corrosive mud and spread it evenly on the surface of the vehicle parts. Record the area of ​​the corrosive mud spread on the surface of the parts as S.

[0077] Vehicle parts covered with corrosive mud were placed in a salt spray chamber and treated with salt spray for 8 hours using the GB / T 10125-2012 (NSS) method.

[0078] Then the vehicle parts are placed in a temperature and humidity control chamber, with the temperature controlled at 50℃ and the humidity at 45%RH, for a processing time of 288 hours;

[0079] After the treatment is completed, the vehicle parts are removed from the temperature and humidity control box, the medium on the surface of the parts is washed off and dried, the changes in the protective coating on the surface of the parts are observed, and the weight of the parts is measured as W2; finally, the corrosion amount per unit area of ​​the surface of the parts is calculated as A, A=(W1-W2) / S.

[0080] In this embodiment, the EIS images of vehicle components after being processed in a temperature and humidity control chamber for 0 hours, 96 hours, and 288 hours are shown below. Figure 1 As shown. By Figure 1 It can be seen that the low-frequency impedance of the corrosive sludge is higher at 96h than at 0h, indicating that the sludge has not yet exerted its corrosive effect at this time, but instead provides a certain protective effect; while the low-frequency impedance of the sludge is lower at 288h than at 0h, indicating that the sludge has already exerted its effect.

[0081] In actual working conditions, when the mud on the road adheres to the vehicle parts, the deicing agent in the mud is first physically isolated from corrosion on the parts, at this time the mud can play a certain protective role, and when the humidity of the mud reaches a certain value, it will begin to corrode the parts.

[0082] The low-frequency impedance of the corrosion mud of the present embodiment is higher than that at 0h when treated in temperature and humidity for 96h, which constitutes a certain protective effect; while the low-frequency impedance of the corrosion mud at 288h is lower than that at 0h, which plays a corrosive role. This is very similar to the corrosion process of the deicing agent in the mud on the parts. Therefore, the corrosion mud of the present embodiment can very realistically and accurately simulate the corrosion effect of the deicing agent on the parts.

[0083] After the corrosion test of the vehicle parts using the corrosion mud, the corrosion state of the surface of the vehicle parts is as shown in Figure 2 It can be seen from Figure 2 that after being corroded by the corrosion mud of the present application, white corrosion marks appear on the surface of the vehicle parts, and the corrosion marks are consistent with the corrosion state of the vehicle parts surface by the deicing agent in actual working conditions.

[0084] Example 2:

[0085] Preparation of corrosion mud:

[0086] Add 90g of kaolin, 15g of iron powder, 4g of ferric oxide and 5g of calcium carbonate into a grinder and uniformly grind and stir for 3h to make the components reach a suitable particle size and be uniformly mixed; slowly pour dilute hydrochloric acid into the ground dry powder in a fume hood, and stir while adding to form a mud; measure the mud using pH paper until the pH of the mud is between 4.5 and 6.6; then dry the mud in an oven at 30℃ for 24h; then put the dried mud into the grinder for further grinding and stirring for 3h to obtain the corrosion mud.

[0087] Corrosion test:

[0088] The vehicle parts with protective plating on the surface were used as the workpieces for the corrosion test. GH-K series cold hardening cast iron pellets with a size of 4mm-5mm were used to hit the vehicle parts under a pressure of 100KPa to damage the protective plating on the surface of the vehicle parts, simulate the impact of small stones on the workpieces and increase the roughness of the surface of the workpieces; the weight of the parts was measured as W1;

[0089] Accurately weigh 5g of the above-mentioned corrosion mud and evenly spread it on the surface of the vehicle parts, and record the spreading area of the corrosion mud on the surface of the vehicle parts as S;

[0090] Put the vehicle parts with the spreaded corrosion mud into a salt spray chamber and perform salt spray treatment for 8h according to the method of GB / T 10125-2012 (NSS).

[0091] Then the vehicle parts are placed in a temperature and humidity control chamber, with the temperature controlled at 50℃ and the humidity at 45%RH, for a processing time of 456 hours.

[0092] After the treatment is completed, the vehicle parts are removed from the temperature and humidity control box, the medium on the surface of the parts is washed off and dried, the changes in the protective coating on the surface of the parts are observed, and the weight of the parts is measured as W2; finally, the corrosion amount per unit area of ​​the surface of the parts is calculated as A, A=(W1-W2) / S.

[0093] In this embodiment, vehicle components were placed in a temperature and humidity control chamber for processing at 0h, 96h, 288h, and 456h, as shown in the EIS diagrams. Figure 3 As shown. By Figure 3 It can be seen that the low-frequency impedance of the corrosion sludge after 96 hours of temperature and humidity treatment is lower than that after 0 hours, indicating that the corrosion sludge has played a role; the low-frequency impedance of the corrosion sludge after 288 hours of temperature and humidity treatment is even lower than that after 96 hours; the corrosion becomes more severe as the time is extended to 466 hours, but this time can no longer reflect the normal corrosion situation.

[0094] After using this corrosive sludge to conduct corrosion tests on vehicle parts, the corrosion state of the vehicle parts surface is as follows: Figure 4 As shown. By Figure 4 As can be seen, after being corroded by the corrosive mud of the present invention, white corrosion marks appear on the surface of the vehicle parts, and the corrosion marks are consistent with the corrosion of the vehicle parts surface by the de-icing agent under actual working conditions.

[0095] Example 3:

[0096] Preparation of corrosive sludge:

[0097] Add 90g of kaolin, 7.5g of iron powder, 2.5g of ferric oxide, and 5g of calcium carbonate to a grinder and grind and stir evenly for 3 hours to ensure that each component reaches a suitable particle size and is evenly mixed. In a fume hood, slowly pour dilute hydrochloric acid into the ground dry powder while stirring to form a mud-like consistency. Measure the pH of the mud using pH test paper until the pH is between 4.5 and 6.6. Then, dry the mud in a drying oven at 30°C for 24 hours. Finally, put the dried mud into a grinder and grind and stir thoroughly for 1 hour to obtain corroded mud.

[0098] Corrosion test:

[0099] The vehicle parts with protective coating on the surface are used as the workpieces for corrosion test. The GH-K series cold hardening cast iron pellets with a size of 4mm-5mm are used to hit the vehicle parts under a pressure of 100KPa to damage the protective coating on the surface of the vehicle parts, simulate the hitting of the workpieces by small stones and increase the roughness of the surface of the workpieces; the weight of the vehicle parts is measured as W1.

[0100] 5g of the above corrosion mud is accurately weighed and evenly laid on the surface of the vehicle parts, and the laying area of the corrosion mud on the surface of the vehicle parts is recorded as S;

[0101] The vehicle parts with the laid corrosion mud are put into a salt spray chamber, and the GB / T 10125-2012(NSS) method is used for salt spray treatment for 10h;

[0102] Then, the vehicle parts are put into a temperature and humidity control chamber, the temperature is controlled at 50℃, the humidity is controlled at 50%RH, and the treatment time is 168h;

[0103] After the treatment, the vehicle parts are taken out of the temperature and humidity control chamber, the medium on the surface of the vehicle parts is washed and dried, the change of the protective coating on the surface of the vehicle parts is observed, the weight of the vehicle parts is measured as W2; finally, the corrosion amount A of the vehicle parts per unit area is calculated, A=(W1-W2) / S.

[0104] In this embodiment, the EIS diagrams of the vehicle parts after being put into the temperature and humidity control chamber for treatment for 0h, 48h, 96h and 168h are as shown in Figure 5 It can be seen from Figure 5 that the low-frequency impedance of the corrosion mud after the treatment for 48h is lower than that after the treatment for 0h, which indicates that the corrosion mud has played a role.

[0105] After the corrosion test of the vehicle parts by using the corrosion mud, the corrosion state of the surface of the vehicle parts is as shown in Figure 6 It can be seen from Figure 6 that after the corrosion by the corrosion mud of the present application, the surface of the vehicle parts appears white corrosion traces, which are consistent with the corrosion state of the surface of the vehicle parts by the snow-melting agent in the actual working condition.

[0106] Example 4:

[0107] Preparation of the corrosion mud:

[0108] Put kaolin 90g, iron powder 10g and calcium carbonate 5g into a grinder and grind and stir for 3h to make the components reach a suitable particle size and be uniformly mixed; slowly pour dilute hydrochloric acid into the ground dry powder in a fume hood, and stir while adding to make the components into a mud; measure the mud using pH paper until the pH of the mud is between 4.5 and 6.6; then dry the mud in a drying oven at 30℃ for 3h; and then put the dried mud into a grinder and grind and stir for 3h to obtain the corrosion mud.

[0109] Corrosion test:

[0110] The vehicle parts with a protective plating layer on the surface are used as the workpieces for the corrosion test. The GH-K series cold hardening cast iron pellets with a size of 4mm-5mm are used to hit the vehicle parts under a pressure of 100KPa to damage the protective plating layer on the surface of the vehicle parts, simulate the hitting of the workpieces by small stones, and increase the roughness of the surface of the workpieces; and the weight of the vehicle parts is measured as W1.

[0111] 5g of the above-mentioned corrosion mud is accurately weighed and uniformly laid on the surface of the vehicle parts, and the laying area of the corrosion mud on the surface of the vehicle parts is recorded as S.

[0112] The vehicle parts with the laid corrosion mud are put into a salt spray chamber, and the GB / T 10125-2012 (NSS) method is used for salt spray treatment for 12h.

[0113] Then the vehicle parts are put into a temperature and humidity control chamber, the temperature is controlled at 35℃, the humidity is controlled at 50%RH, and the treatment time is 288h.

[0114] After the treatment is completed, the vehicle parts are taken out of the temperature and humidity control chamber, the medium on the surface of the vehicle parts is washed, and then the vehicle parts are dried, the change of the protective plating layer on the surface of the vehicle parts is observed, and the weight of the vehicle parts is measured as W2; finally, the corrosion amount per unit area of the surface of the vehicle parts A is calculated, A=(W1-W2) / S.

[0115] In this embodiment, the EIS diagrams of the vehicle parts after being put into the temperature and humidity control chamber for treatment for 0h, 96h and 288h are as shown in Figure 7 It can be seen from Figure 7 that the low-frequency impedance of the corrosion mud at 96h is lower than that at 0h, which indicates that the corrosion mud has played a role.

[0116] After the corrosion test of the vehicle parts using the corrosion mud, the corrosion state of the surface of the vehicle parts is as shown in Figure 8 It can be seen from Figure 8 that after the corrosion of the corrosion mud of the present application, white corrosion traces appear on the surface of the vehicle parts, and the corrosion state is consistent with the corrosion state of the vehicle parts by the snow-melting agent in the actual working condition.

[0117] Example 5:

[0118] Preparation of the corrosion mud:

[0119] Put 90g of kaolin, 10g of ferroferric oxide and 5g of calcium carbonate into a grinder and grind and stir for 3h to make the components reach a suitable particle size and be uniformly mixed; slowly pour dilute hydrochloric acid into the ground dry powder in a fume hood, and stir while adding to make the components into mud; measure the mud with pH paper until the pH of the mud is between 4.5 and 6.6; then dry the mud in a drying oven at 30℃ for 3h; then put the dried mud into a grinder and grind and stir for 3h to obtain the corrosion mud.

[0120] Corrosion test:

[0121] The vehicle parts with protective plating on the surface are used as the workpieces for the corrosion test. GH-K series cold hardening cast iron pellets with a size of 4mm-5mm are used to hit the vehicle parts under a pressure of 100KPa to damage the protective plating on the surface of the vehicle parts, simulate the hitting of small stones on the workpieces and increase the roughness of the surface of the workpieces; the weight of the vehicle parts is measured as W1.

[0122] Accurately weigh 5g of the above-mentioned corrosion mud and evenly spread it on the surface of the vehicle parts; the spreading area of the corrosion mud on the surface of the vehicle parts is recorded as S.

[0123] Put the vehicle parts with the spread corrosion mud into a salt spray chamber and perform salt spray treatment for 12h according to the method of GB / T 10125-2012 (NSS).

[0124] Then put the vehicle parts into a temperature and humidity control chamber, control the temperature at 35℃ and the humidity at 50% RH, and the treatment time is 288h.

[0125] After the treatment is completed, take the vehicle parts out of the temperature and humidity control chamber, wash the medium on the surface of the vehicle parts and dry them, observe the changes of the protective plating on the surface of the vehicle parts, and measure the weight of the vehicle parts as W2; finally, calculate the corrosion amount A of the surface of the vehicle parts per unit area, A=(W1-W2) / S.

[0126] After the corrosion test of the vehicle parts is performed by using the corrosion mud, the corrosion state of the surface of the vehicle parts is as shown in Figure 9 It can be seen from Figure 9 that after the corrosion mud of the present application is used for corrosion, white corrosion traces appear on the surface of the vehicle parts, which are consistent with the corrosion state of the vehicle parts caused by the snow melting agent under actual working conditions.

[0127] Comparative Example 1:

[0128] Preparation of the corrosion mud:

[0129] The kaolin 90 g and calcium carbonate 5 g were added into a grinder and uniformly ground and stirred for 3 h to make the components reach a suitable particle size and be uniformly mixed; the ground dry powder was slowly poured into dilute hydrochloric acid in a fume hood, and the components were mixed into a mud while stirring; the prepared mud was measured by pH test paper until the pH of the mud was between 4.5 and 6.6; then the mud was dried in a drying oven at 35°C for 24 h; the dried mud was then put into a grinder and uniformly ground and stirred for 3 h to obtain the corrosion mud.

[0130] Corrosion test:

[0131] The vehicle parts with protective plating on the surface were used as the workpieces for the corrosion test. The GH-K series cold hardening cast iron pellets with a size of 4 mm to 5 mm were used to hit the vehicle parts under a pressure of 100 KPa to damage the protective plating on the surface of the vehicle parts, simulate the hitting of small stones on the workpieces, and increase the roughness of the surface of the workpieces; the weight of the vehicle parts was measured as W1.

[0132] 5 g of the above-mentioned corrosion mud was accurately weighed and uniformly spread on the surface of the vehicle parts, and the spreading area of the corrosion mud on the surface of the vehicle parts was recorded as S.

[0133] The vehicle parts with the spread corrosion mud were put into a salt spray chamber, and the GB / T 10125-2012 (NSS) method was used for salt spray treatment for 12 h.

[0134] Then the vehicle parts were put into a temperature and humidity control chamber, the temperature was controlled at 35°C, the humidity was controlled at 50% RH, and the treatment time was 288 h.

[0135] After the treatment, the vehicle parts were taken out of the temperature and humidity control chamber, the medium on the surface of the vehicle parts was washed and dried, the change of the protective plating on the surface of the vehicle parts was observed, and the weight of the vehicle parts was measured as W2; finally, the corrosion amount A per unit area on the surface of the vehicle parts was calculated, A = (W1-W2) / S.

[0136] After the corrosion test of the vehicle parts using the corrosion mud, no corrosion marks appeared on the surface of the vehicle parts, and the corrosion condition was not consistent with the corrosion condition of the vehicle parts by the snow-melting agent in the actual working condition. At the same time, the impedance spectrum Figure 10 It can be seen that the impedance spectrum is almost the same as that at 0 h after 96 h and 288 h, indicating that the corrosion mud does not have a corrosion effect.

[0137] Comparative Example 2:

[0138] Preparation of the corrosion mud:

[0139] Put kaolin 90g, iron powder 5g and calcium carbonate 60g into a grinder and grind and stir for 3h to make the components reach a suitable particle size and mix uniformly; slowly pour dilute hydrochloric acid into the ground dry powder in a fume hood, and stir while adding to make the components into a mud; measure the mud with pH paper until the pH of the mud is between 4.5 and 6.6; then dry the mud in a drying oven at 35℃ for 24h; then put the dried mud into a grinder and grind and stir for 3h to obtain the corrosion mud.

[0140] Corrosion test:

[0141] The vehicle parts with protective plating on the surface are used as the workpieces for the corrosion test. The GH-K series cold hardening cast iron pellets with a size of 4mm-5mm are used to hit the vehicle parts under a pressure of 100KPa to damage the protective plating on the surface of the vehicle parts, simulate the hitting of small stones on the workpieces, and increase the roughness of the surface of the workpieces; the weight of the vehicle parts is measured as W1.

[0142] Accurately weigh 5g of the above-mentioned corrosion mud and evenly spread it on the surface of the vehicle parts; the spreading area of the corrosion mud on the surface of the vehicle parts is recorded as S.

[0143] Put the vehicle parts with the spread corrosion mud into a salt spray chamber and use the method of GB / T 10125-2012(NSS) to perform salt spray treatment for 12h.

[0144] Then put the vehicle parts into a temperature and humidity control chamber, control the temperature at 35℃ and the humidity at 50%RH, and treat for 168h.

[0145] After the treatment, take the vehicle parts out of the temperature and humidity control chamber, wash the medium on the surface of the vehicle parts, dry, observe the changes of the protective plating on the surface of the vehicle parts, and measure the weight of the vehicle parts as W2; finally, calculate the corrosion amount A of the surface of the vehicle parts per unit area, A=(W1-W2) / S.

[0146] After the corrosion test of the vehicle parts using the corrosion mud, no corrosion marks appear on the surface of the vehicle parts, and the corrosion condition does not match the corrosion condition of the vehicle parts by the snow-melting agent in the actual working condition. At the same time, the impedance spectrum Figure 11 It can be seen that the impedance spectrum is almost the same as that at 0h after 48h, 96h and 168h, indicating that the corrosion mud does not have corrosion effect.

[0147] The technical features of the above-mentioned embodiments can be combined arbitrarily, and to make the description simple, all possible combinations of the technical features in the above-mentioned embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

[0148] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method of corrosion testing of a coating on a surface of a workpiece, characterized by, The method comprises the following steps: The surface of the workpiece is hit by cold hard cast iron pellets, and the weight of the workpiece is measured and recorded as W1; The corrosion mud is evenly laid on the surface of the workpiece, and the laying area of the corrosion mud on the surface of the workpiece is recorded as S; The workpiece with the surface laid with the corrosion mud is placed in a salt spray chamber for salt spray corrosion for 6h-10h; The workpiece after the salt spray corrosion is placed in a temperature and humidity control box for treatment, the temperature in the temperature and humidity control box is 25℃-55℃, the humidity is 40%RH-50%RH, and the treatment time is 168h-288h; and The workpiece is taken out, the corrosion mud on the surface of the workpiece is removed, the weight of the workpiece is measured and recorded as W2, and the corrosion amount A of the workpiece per unit area is calculated, A=(W1-W2) / S; The corrosion mud comprises, by weight fraction, 80-100 parts of kaolin, 10-60 parts of an iron source, and 1-10 parts of a calcium source; the pH of the corrosion mud is 4.5-6.6; the iron source is iron powder and ferroferric oxide, and the mass ratio of the iron powder to the ferroferric oxide is (1-4):

1.

2. The method of claim 1, wherein the method is a corrosion test method for a surface coating of a workpiece. The corrosion mud comprises, by weight fraction, 85-95 parts of kaolin, 15-50 parts of an iron source, and 3-10 parts of a calcium source.

3. The method of claim 1, wherein the method is a corrosion test method for a surface coating of a workpiece. The corrosion mud comprises, by weight fraction, 89-90 parts of kaolin, 19-50 parts of an iron source, and 5-10 parts of a calcium source.

4. The corrosion test method of a plated layer on a workpiece surface according to any one of claims 1 to 3, characterized in that, The calcium source is one or more of calcium carbonate, calcium sulfate, calcium nitrate, and calcium chloride. The calcium source is one or more of calcium carbonate, calcium sulfate, calcium nitrate, and calcium chloride.

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