CN116678814A - Corrosion resistance evaluation method - Google Patents
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- 238000005260 corrosion Methods 0.000 title claims abstract description 240
- 230000007797 corrosion Effects 0.000 title claims abstract description 240
- 238000011156 evaluation Methods 0.000 title claims abstract description 36
- 238000012360 testing method Methods 0.000 claims abstract description 88
- 229910052751 metal Inorganic materials 0.000 claims abstract description 75
- 239000002184 metal Substances 0.000 claims abstract description 75
- 239000000758 substrate Substances 0.000 claims abstract description 74
- 150000003839 salts Chemical class 0.000 claims abstract description 68
- 239000007921 spray Substances 0.000 claims abstract description 68
- 238000006056 electrooxidation reaction Methods 0.000 claims abstract description 61
- 238000013210 evaluation model Methods 0.000 claims abstract description 51
- 238000000576 coating method Methods 0.000 claims abstract description 47
- 239000011248 coating agent Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 8
- 238000001962 electrophoresis Methods 0.000 claims description 5
- 230000011218 segmentation Effects 0.000 description 11
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
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- 239000007864 aqueous solution Substances 0.000 description 3
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- 239000007788 liquid Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 238000000840 electrochemical analysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001453 impedance spectrum Methods 0.000 description 1
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- 238000002844 melting Methods 0.000 description 1
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Abstract
The application relates to a corrosion resistance evaluation method, which comprises the following steps: providing N standard samples, wherein the standard samples comprise metal substrates and coatings arranged on the metal substrates, the roughness of the metal substrates of the standard samples is different, N is more than or equal to 3, and N is an integer. And obtaining the contact angle, the electrochemical corrosion resistance and the corrosion resistance time of the salt spray test of each standard sample. The contact angle, the electrochemical corrosion resistance and the corrosion resistance time of the salt spray test of the same standard sample are taken as a group of data sets, and a corrosion resistance evaluation model of a sample to be tested is constructed according to N groups of data sets of N standard samples; the sample to be tested comprises a metal substrate and a coating arranged on the metal substrate. And acquiring the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance. And evaluating the corrosion resistance of the sample to be tested according to the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance.
Description
Technical Field
The application relates to the technical field of component performance detection, in particular to a corrosion resistance evaluation method.
Background
The corrosion resistance of the metal automobile part can be improved by arranging the coating on the surface of the metal automobile part, and the service life of the metal automobile part is directly influenced by the protective performance of the coating. With the continuous development of the automobile field, the requirements on the protective performance of the coating are also higher and higher. Corrosion resistance is one of the important indexes for evaluating the protection performance of the coating.
At present, corrosion resistance of automobile parts is evaluated by methods such as salt spray test and actual environment exposure test, but the methods generally need 1 month or more to obtain test results, which greatly affects the development period of the coating. And the accuracy of the traditional coating corrosion resistance evaluation method is low. Therefore, if the corrosion resistance of the coating can be rapidly and accurately evaluated, timely and reliable information can be provided for the research, the design and the application of the coating, and reference can be provided for the future maintenance of related products.
Disclosure of Invention
Based on the above, it is necessary to provide a corrosion resistance evaluation method to improve the efficiency and accuracy of corrosion resistance evaluation of parts.
The corrosion resistance evaluation method provided by the application comprises the following steps:
acquiring contact angles, electrochemical corrosion resistance and corrosion resistance time of the salt spray test of N standard samples; the standard samples comprise metal substrates and coatings arranged on the metal substrates, and the roughness of the metal substrates of the standard samples is different, wherein N is more than or equal to 3, and N is an integer;
taking the contact angle, the electrochemical corrosion resistance and the salt spray test corrosion resistance time of the same standard sample as a group of data sets, and constructing a corrosion resistance evaluation model of a sample to be tested according to N groups of data sets of the N standard samples; the sample to be tested comprises a metal substrate and a coating arranged on the metal substrate;
acquiring the roughness of a metal substrate of the sample to be detected, the contact angle of the sample to be detected and the electrochemical corrosion resistance of the sample to be detected; and
And obtaining the corrosion resistance evaluation result of the sample to be tested according to the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance of the sample to be tested.
According to the corrosion resistance evaluation method, the corrosion resistance evaluation model is constructed based on the acquired N groups of data sets by acquiring the contact angle, the electrochemical corrosion resistance and the corrosion resistance time data of the N standard samples, and then the corrosion resistance of the sample to be evaluated is evaluated by utilizing the evaluation model in combination with the roughness, the contact angle and the electrochemical corrosion resistance of the metal substrate of the sample to be evaluated, so that the corrosion resistance of the sample to be evaluated can be evaluated without carrying out a salt spray test on the sample to be evaluated, and the time of the evaluation test can be effectively shortened. Further, the corrosion resistance of the parts is mainly influenced by the corrosion resistance of the coating material, the surface property of the coating and the thickness uniformity of the coating, and the thickness uniformity of the coating is influenced by the roughness of the metal substrate, so that the corrosion resistance of the sample to be tested can be accurately evaluated according to the roughness of the standard sample and the corrosion resistance evaluation model. In addition, the corrosion resistance evaluation method provided by the application is simple in steps and wide in applicability.
In some of these embodiments, the roughness of the metal substrate of each of the standard samples satisfies the following relationship:
and marking N standard samples as 1 st to N th standard samples in sequence from the roughness to the roughness, wherein the ratio of the N standard sample to the roughness of the N-1 st standard sample is 1.8-2.5, N is more than 1 and less than or equal to N, and N is an integer.
In some of these embodiments, the roughness of the metal substrate of each of the standard samples is independently selected from 0.8 μm to 100 μm.
In some of these embodiments, the number of standard samples is 7, and the roughness of the metal substrate in each of the standard samples is 0.8 μm, 1.6 μm, 3.2 μm, 6.3 μm, 12.5 μm, 25.0 μm, and 50.0 μm, respectively.
In some embodiments, the N standard samples and the sample to be tested use metal substrates of the same material.
In some of these embodiments, the coating is formed on the metal substrate of the N standard samples and the sample to be tested using the same electrophoresis process.
In some embodiments, the step of constructing a corrosion resistance evaluation model of the sample to be tested according to the N groups of data sets of the N standard samples includes:
according to the electrochemical corrosion resistance and the corrosion resistance time of each salt spray test in the N groups of data sets, a first relation and a linear correlation coefficient R of linear fitting between the electrochemical corrosion resistance and the corrosion resistance time of the salt spray test are obtained 1 2 ；
Obtaining a second relation and a linear correlation coefficient R of linear fitting between the contact angle and the corrosion resistance time of the salt spray test according to the contact angles and the corrosion resistance time of the salt spray test in the N groups of data sets 2 2 ；
According to R 1 2 And R is 2 2 And determining a corrosion resistance evaluation model.
In some of these embodiments, according to R 1 2 And R is 2 2 A step of determining a corrosion resistance evaluation model, comprising:
if R is 1 2 Not less than a and R 2 2 < a, taking the first relation as the corrosion resistance evaluation model;
if R is 2 2 Not less than a and R 1 2 < a, using the second relation as the corrosion resistance evaluation model;
if R is 1 2 Not less than a and R 2 2 Not less than a, R 1 2 And R is 2 2 The corresponding relation of the relatively larger one of the three is used as the corrosion resistance evaluation model;
if R is 1 2 < a and R 2 2 A, performing binary fitting or piecewise fitting on the N groups of data sets to obtain the corrosion resistance evaluation model;
wherein a is a preset linear correlation coefficient.
In some embodiments, if R 1 2 ＜a，R 2 2 And a is less than or equal to 3 and less than or equal to 5, and binary fitting is carried out on the N groups of data sets.
In some embodiments, if R 1 2 ＜a，R 2 2 And (3) a, wherein N is more than or equal to 5, and performing piecewise fitting on the N groups of data sets.
In some of these embodiments, the step of performing a binary fit to the N sets of data sets comprises:
and obtaining a third relation of linear fitting among the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test according to the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test in the N groups of data sets, and taking the third relation as the corrosion resistance evaluation model.
In some embodiments, the step of obtaining the corrosion resistance evaluation result of the sample to be tested according to the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance of the sample to be tested includes:
acquiring a corresponding corrosion resistance relation according to the roughness of the metal substrate of the sample to be detected;
according to the acquired corrosion resistance relation, combining the contact angle of the sample to be tested and the electrochemical corrosion resistance to obtain the salt spray test corrosion resistance time of the sample to be tested;
and according to the corrosion resistance time of the salt spray test of the sample to be tested, obtaining the corrosion resistance evaluation result of the sample to be tested.
Detailed Description
The present application will be described more fully hereinafter in order to facilitate an understanding of the present application. This application may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, 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 herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
The coating corrosion prevention technology is widely applied to various fields, and the corrosion resistance of the coating prepared on the surface of the automobile metal part can be effectively improved. At present, corrosion resistance of parts is mainly evaluated by methods such as salt spray test, actual environment exposure test and the like. However, the above method generally requires 1 month or more to obtain the test results, which has a great influence on the coating development period. Based on the above problems, the inventors of the present application found that corrosion of parts is mainly affected by corrosion resistance of coating materials themselves, surface properties of coatings, and uniformity of thickness of coatings, so that samples to be measured can be rapidly and accurately evaluated by establishing a relationship between the three and corrosion resistance. Therefore, the application provides a brand-new corrosion resistance evaluation method.
An embodiment of the present application provides a corrosion resistance evaluation method, including the following steps S100 to S400.
S100, acquiring contact angles, electrochemical corrosion resistance and corrosion resistance time of N standard samples in a salt spray test; the standard samples comprise metal substrates and coatings arranged on the metal substrates, wherein the roughness of the metal substrates of the standard samples is different, N is more than or equal to 3, and N is an integer.
Contact angle data of each standard sample is obtained through a contact angle test, and the contact angle test is carried out by adopting water, 5wt% NaCl aqueous solution or 5wt% snow melting saline aqueous solution and the like as liquid so as to simulate the corrosion environment of parts. And obtaining an alternating current impedance diagram of each standard sample through an electrochemical impedance spectrum test, and obtaining electrochemical corrosion impedance through fitting. The contact angle and the electrochemical corrosion resistance are data of the coating material.
And adopting a salt spray test to carry out a simulated corrosion test on each standard sample so as to obtain corresponding corrosion resistance time. Illustratively, scribing the standard sample, placing the scribed standard sample in a salt spray test device, and testing the corrosion-resistant time of the salt spray test by using the time when the corrosion-resistant distance is greater than or equal to 2mm for the first time every 24 hours at the scribing position of the standard sample.
It is understood that the roughness of the substrate can affect the uniformity of the coating thickness and thus the corrosion resistance of the component. As the roughness of the substrate increases, the thickness of the coating becomes uneven throughout, and the thinner areas of the coating are prone to corrosion, thereby resulting in reduced corrosion resistance of the entire component. Therefore, the embodiment adopts the metal substrates with different roughness to construct the standard samples with different corrosion resistance, and can accurately evaluate the corrosion resistance of the sample to be tested. In addition, the applicability of the evaluation method can be extended by adjusting parameters such as the roughness of the metal substrate.
In some of these embodiments, the roughness of the metal substrate of each standard sample satisfies the following relationship:
and marking N standard samples as 1 st to N th standard samples in sequence from the roughness to the roughness of the N-1 st standard sample, wherein the ratio of the roughness of the N-1 st standard sample to the roughness of the N-1 st standard sample is 1.8-2.5, N is more than 1 and less than or equal to N, and N is an integer. Optionally, the ratio of the roughness of the nth standard sample to the n-1 st standard sample is 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or 2.5.
In some of these embodiments, the roughness of the metal substrate of each standard sample is independently selected from 0.8 μm to 100 μm. The metal substrate can be a roughness calibration block obtained by direct purchase, or can be prepared according to actual needs. The roughness of the metal substrate is in the range, so that the requirement of corrosion resistance evaluation of automobile parts can be met.
In some of these embodiments, the number of standard samples is 7, and the roughness of the metal substrate in each standard sample is 0.8 μm, 1.6 μm, 3.2 μm, 6.3 μm, 12.5 μm, 25.0 μm, and 50.0 μm, respectively.
In some of these embodiments, the same electrophoretic process is used to form the coating on N standard samples of different roughness of the metal substrate. The same electrophoresis process is adopted to prepare the coating with the approximate overall thickness on the metal substrate with different roughness, so that the evaluation accuracy is improved. It should be noted that the roughness of the metal substrate hardly affects the thickness of the coating, but affects the uniformity of the thickness of the coating. In addition, the method also comprises the pretreatment steps of degreasing, phosphating and the like on the metal substrate before electrophoresis.
In some of these embodiments, the coating has a thickness of 12 μm to 15 μm.
S200, taking the contact angle, the electrochemical corrosion resistance and the salt spray test corrosion resistance time of the same standard sample as a group of data sets, and constructing a corrosion resistance evaluation model of a sample to be tested according to N groups of data sets of N standard samples; the sample to be tested comprises a metal substrate and a coating arranged on the metal substrate.
By constructing a corrosion resistance evaluation model and combining the substrate roughness of the sample to be tested, the contact angle of the coating and the electrochemical corrosion resistance, the corrosion resistance of the sample to be tested can be rapidly evaluated. That is, the corrosion resistance of the sample to be tested can be estimated without performing a long-time salt spray test on the sample.
In some of these embodiments, the N standard samples and the sample to be tested use metal substrates of the same material. It is understood that, in order to improve accuracy of the evaluation result, the metal substrates of the standard sample and the sample to be tested are made of the same material, for example, the standard sample and the sample to be tested are both made of 80 # steel as the metal substrate, and the sample to be tested is different from each standard sample in roughness.
In some of these embodiments, the same electrophoretic process as the standard sample is used to form a coating on the metal substrate of the sample to be tested.
In some embodiments, the construction of the corrosion resistance evaluation model of the sample to be tested according to the N sets of data sets of the N standard samples includes the following steps S210 to S220.
S210, obtaining a first relation and a linear correlation coefficient R of linear fitting between the electrochemical corrosion resistance and the salt spray test corrosion resistance time according to the electrochemical corrosion resistance and the salt spray test corrosion resistance time in the N groups of data sets 1 2 ；
S220, obtaining a second relation and a linear correlation coefficient R of linear fitting between the contact angle and the corrosion resistance time of the salt spray test according to the contact angles and the corrosion resistance time of the salt spray test in the N groups of data sets 2 2 ；
S230, according to R 1 2 And R is 2 2 And determining a corrosion resistance evaluation model.
It is understood that in this embodiment, the test data of all the standard samples are subjected to full-segment fitting, and the corrosion resistance evaluation model is determined according to the fitted linear correlation coefficient.
In some of these embodiments, S230 includes:
if R is 1 2 Not less than a and R 2 2 A, taking the first relation as a corrosion resistance evaluation model;
if R is 2 2 Not less than a and R 1 2 A, taking the second relation as a corrosion resistance evaluation model;
if R is 1 2 Not less than a and R 2 2 Not less than a, R 1 2 And R is 2 2 The corresponding relation of the relatively larger one is used as a corrosion resistance evaluation model;
if R is 1 2 < a and R 2 2 Performing binary fitting or piecewise fitting on the N groups of data sets to obtain a corrosion resistance evaluation model;
wherein a is a preset linear correlation coefficient.
In some embodiments, a is 0.75 to 1. Alternatively, a is 0.75, 0.8, 0.85, 0.9, 0.95, or 0.99. The value of a can be selected according to the types of the parts and the actual application requirements, and the application is not limited to the above.
Understandably, when R 1 2 Not less than a and R 2 2 When the resistance is less than a, the linear relation between the electrochemical corrosion resistance data and the corrosion resistance time of the salt spray test is better, which indicates that the electrochemical corrosion resistance data can be used for evaluating the corrosion resistance at the moment; when R is 2 2 Not less than a and R 1 2 When the contact angle is less than a, the linear relation between the contact angle and the corrosion resistance time of the salt spray test is better, which indicates that the contact angle can be used for evaluating the corrosion resistance at the moment; when R is 1 2 Not less than a and R 2 2 More than or equal to a, in order to improve the accuracy of the evaluation result, a corresponding relation with a larger one of the two is required to be selected to evaluate the corrosion resistance; when R is 1 2 < a and R 2 2 And a, the corrosion resistance is influenced by the corrosion resistance of the coating, the surface property of the coating and the thickness uniformity of the coating, and the influence degree of each factor is different, so that the corrosion resistance of the sample to be measured can be accurately evaluated only by binary fitting or sectional fitting of N groups of data sets.
Further, if R 1 2 ＜a，R 2 2 And a is less than or equal to 3 and less than or equal to 5, and binary fitting is carried out on the N groups of data sets. If R is 1 2 ＜a，R 2 2 And (3) a, wherein N is more than or equal to 5, and performing piecewise fitting on the N groups of data sets.
Understandably, when the number of standard samples is small, a binary fitting mode is adopted to obtain the corrosion resistance evaluation model. When the number of the quasi-samples is large, in order to improve the accuracy of the evaluation result, a segment fitting mode is adopted to obtain the corrosion resistance evaluation model.
In some of these embodiments, performing a binary fit on the N sets of data sets includes:
and obtaining a third relation of linear fitting among the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test according to the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test in the N groups of data sets, and taking the third relation as a corrosion resistance evaluation model.
Understandably, when the number of standard samples is small, the electrochemical corrosion resistance data and the contact angle are taken as variables at the same time, and the corrosion resistance time of the salt spray test is linearly fitted to obtain a corresponding relational expression, so that the corrosion resistance performance is evaluated.
In some of these embodiments, a piecewise fit is performed on the N sets of data sets. It is understood that when the number of standard samples is large, in order to improve the accuracy of the evaluation result, a segment fitting manner may be used to construct the corrosion resistance evaluation model. Illustratively, the segment fitting includes the steps of:
(1) Numbering device
The data sets corresponding to the 1 st and nth standard samples are referred to as the 1 st data set and the nth data set, respectively.
(2) Acquiring m segmented data sets
Taking 3 data sets from the 1 st to the 3 rd data sets as a group of sets to obtain a linear correlation coefficient A of linear fitting between the electrochemical corrosion resistance of the first section and the corrosion resistance time of the salt spray test 1 2 . Taking the total of 4 data sets from the 1 st to the 4 th data sets as a group of sets to obtain a linear correlation coefficient A of linear fitting between the electrochemical corrosion resistance of the first section and the corrosion resistance time of the salt spray test 2 2 . If A 1 2 Not less than b, and A 2 2 < b, then take dataset No. 3 as dataset of segmentation 1; if A 2 2 Not less than b, and A 1 2 < b, then take dataset No. 4 as dataset of segment 1; if A 1 2 Not less than b, and A 2 2 More than or equal to b, then with A 1 2 And A 2 2 The corresponding data set of the relatively larger one of (2) is taken as the 1 st segment data set; if A 1 2 < b, and A 2 2 And b, segmenting according to the correlation degree between the contact angle and the corrosion resistance time of the salt spray test.
The specific steps for segmentation according to the correlation degree between the contact angle and the corrosion resistance time of the salt spray test are as follows: taking 3 data sets from the 1 st to the 3 rd data sets as a group of sets to obtain a linear correlation coefficient of linear fitting between the contact angle of the first segment and the corrosion resistance time of the salt spray testB 1 2 . Taking the total of 4 data sets from the 1 st to the 4 th data sets as a group of sets to obtain a linear correlation coefficient B of the linear fit between the contact angle of the first segment and the corrosion resistance time of the salt spray test 2 2 . If B 1 2 Not less than B, and B 2 2 < b, then take dataset No. 3 as dataset of segmentation 1; if B 2 2 Not less than B, and B 1 2 < b, then take dataset No. 4 as dataset of segment 1; b (B) 1 2 Not less than B, and B 2 2 Not less than B, then B 1 2 And B 2 2 The corresponding data set of the relatively larger one of (2) is taken as the 1 st segment data set; if B 1 2 < B, and B 2 2 And b, segmenting according to the correlation degree among the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test.
The specific steps of segmentation according to the correlation degree among the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test are as follows: taking 3 data sets from the 1 st data set to the 3 rd data set as a group of data sets to obtain a linear correlation coefficient C of linear fitting between the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test of the first section 1 2 . Taking the total of 4 data sets from the 1 st to the 4 th data sets as a group of sets to obtain a linear correlation coefficient C of the linear fit between the contact angle of the first segment and the corrosion resistance time of the salt spray test 2 2 . If C 1 2 Not less than b, and C 2 2 < b, then take dataset No. 3 as dataset of segmentation 1; if C 2 2 Not less than b, and C 1 2 < b, then take dataset No. 4 as dataset of segment 1; if C 1 2 Not less than b, and C 2 2 Not less than b, then C 1 2 And C 2 2 The corresponding data set of the relatively larger one of (2) is referred to as the 1 st segment data set.
After the 1 st segmented data set is acquired, the remaining data sets in the N sets of data sets are segmented according to the same segmentation method to acquire m segmented data sets.
B is a preset linear correlation coefficient, and b is 0.75 to 1. The value of b can be selected according to the types of the parts and the actual application requirements, and the application is not limited to the above. In addition, the segmentation needs to be performed to ensure that each fitting segment at least comprises 3 data sets, and if the number of the data sets is less than 3, the segmentation is not needed.
(3) Segment fitting N datasets
Taking the data set 1 to the data set 1 as a first fitting section, and obtaining a fourth relation and a linear correlation coefficient D of linear fitting between the electrochemical corrosion resistance and the salt spray test corrosion resistance time according to the electrochemical corrosion resistance and the salt spray test corrosion resistance time in each data set in the first fitting section 1 2 . According to each contact angle and each corrosion resistant time of the salt spray test in each data set in the first fitting section, obtaining a fifth relation and a linear correlation coefficient D of linear fitting between the contact angle and the corrosion resistant time of the salt spray test 2 2 。
If D 1 2 Not less than c and D 2 2 And c, taking the fourth relation as the corrosion resistance relation of the first fitting section. If D 2 2 Not less than c and D 1 2 C, taking a fifth relation as a corrosion resistance relation of the first fitting section; if D 1 2 Not less than c and D 2 2 Not less than c, in D 1 2 And D 2 2 The corresponding relation of the relatively larger one is used as the corrosion resistance relation of the first fitting section; if D 1 2 < c and D 2 2 And c, performing binary fitting according to the electrochemical corrosion resistance, the contact angles and the corrosion resistance time of the salt spray tests in the first fitting section to obtain a sixth relation of linear fitting among the electrochemical corrosion resistance, the contact angles and the corrosion resistance time of the salt spray tests, wherein the sixth relation is used as the corrosion resistance relation of the first fitting section.
And performing data fitting on a second fitting segment formed by the 1 st segment data set to the 2 nd segment data set and an (m-1) th fitting segment formed by the (m-1) th segment data set to the m th segment data set in the same manner to obtain a corrosion resistance relation corresponding to each fitting segment, wherein m is an integer greater than 2.
C is a preset linear correlation coefficient, and c is 0.75 to 1. The value of c can be selected according to the types of the parts and the actual application requirements, and the application is not limited to the above.
(4) Construction of corrosion resistance evaluation model
And constructing a corrosion resistance evaluation model according to the corrosion resistance relation of each fitting segment and the corresponding roughness interval of each fitting segment.
S300, acquiring the roughness of a metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance of the sample to be tested.
The contact angle and the electrochemical corrosion resistance of the sample to be measured are obtained by adopting the same test method as the standard sample.
S400, according to the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance of the sample to be tested, obtaining the corrosion resistance evaluation result of the sample to be tested.
In some of these embodiments, step S400 includes:
acquiring a corresponding corrosion resistance relation according to the roughness of the metal substrate of the sample to be tested;
according to the acquired corrosion resistance relation, combining the contact angle and the electrochemical corrosion resistance of the sample to be tested to obtain the salt spray test corrosion resistance time of the sample to be tested;
and according to the corrosion resistance time of the salt spray test of the sample to be tested, obtaining the corrosion resistance evaluation result of the sample to be tested.
Understandably, the roughness interval of the metal substrate of the sample to be tested is confirmed through the roughness of the metal substrate, so that the corresponding corrosion resistance relation is confirmed, and then the contact angle and the electrochemical corrosion resistance of the sample to be tested are brought into the relation, so that the corrosion resistance time of the salt spray test of the sample to be tested can be obtained, and the corrosion resistance of the sample to be tested can be evaluated. Therefore, the corrosion resistance of the sample to be tested can be evaluated according to the actual roughness of the sample to be tested, and the accuracy of the evaluation result is improved.
According to the corrosion resistance evaluation method, the corrosion resistance evaluation model is constructed based on the acquired N groups of data sets by acquiring the contact angle, the electrochemical corrosion resistance and the corrosion resistance time data of the N standard samples, and then the corrosion resistance of the sample to be evaluated is evaluated by utilizing the evaluation model in combination with the roughness, the contact angle and the electrochemical corrosion resistance of the metal substrate of the sample to be evaluated, so that the corrosion resistance of the sample to be evaluated can be evaluated without carrying out a salt spray test on the sample to be evaluated, and the time of the evaluation test can be effectively shortened. Further, the corrosion resistance of the parts is mainly influenced by the corrosion resistance of the coating material, the surface property of the coating and the thickness uniformity of the coating, and the thickness uniformity of the coating is influenced by the roughness of the metal substrate, so that the corrosion resistance of the sample to be tested can be accurately evaluated according to the roughness of the standard sample and the corrosion resistance evaluation model. In addition, the corrosion resistance evaluation method provided by the application is simple in steps and wide in applicability.
The following are specific examples.
Example 1
1. Preparation of a Standard sample
The surface roughness of the polished (shot) sample block of precision template tool factory in Harbin city is compared by taking No. 80 steel plates with the surface roughness of 0.8 μm, 1.6 μm, 3.2 μm, 6.3 μm, 12.5 μm, 25 μm and 50 μm as metal substrates. And carrying out standard pretreatment on the 7 metal substrates, and then adopting the same conventional electrophoresis process to prepare a coating on the surfaces of the metal substrates to obtain 7 standard samples. The standard samples including the metal substrate having a surface roughness of 0.8 μm were recorded as No. 1 standard samples in order of the metal substrate roughness from small to large, and the standard samples including the metal substrate having a surface roughness of 50 μm were recorded as No. 7 standard samples, by analogy.
2. Performance test of standard samples
Contact angle testing of each standard sample was performed in accordance with DIN55660-3, with water as the test liquid. And (3) carrying out electrochemical test on each standard sample by adopting a three-electrode system, wherein the reference electrode is a saturated calomel electrode, the auxiliary electrode is a platinum electrode, the test medium is 3.5wt% NaCl aqueous solution, and the corrosion resistance Rp is obtained by fitting according to the measured spectrogram. Each standard sample was subjected to 3 tests, and the average value of 3 tests was taken as the contact angle θ and the electrochemical corrosion resistance Rp of the corresponding sample.
According to the salt spray test of national standard GB/T10125, the standard sample is streaked before the test. And detecting the corrosion expansion distance at the scribing position every 24 hours, and recording the time when the corrosion expansion distance is larger than or equal to 2mm for the first time, thereby being used as the corrosion resistance time of the salt spray test. The specific test results are shown in table 1.
TABLE 1
3. Construction of corrosion resistance evaluation model
The contact angle, electrochemical corrosion resistance and corrosion resistance time data of the 1 st standard sample in table 1 are recorded as a group of data sets, which are recorded as the 1 st data set, and by analogy, the contact angle, electrochemical corrosion resistance and corrosion resistance time data of the 7 th standard sample are recorded as the 7 th data set. The corrosion resistance evaluation model of the sample to be tested is constructed according to the following method.
(1) Full segment fitting
Fitting is carried out by adopting the contact angle theta and the corrosion resistance time T of the data sets from 1 to 7, and the following relational expression (1) is obtained: t= 17.233 ×θ -702.62, corresponding R 1 2 =0.637. Fitting with the corrosion resistance Rp and the corrosion resistance time T of the data sets 1 to 7 to obtain the following relational expression (2): t= 81.364 ×10 -7 X Rp-79.967, corresponding R 2 2 = 0.1947. And the preset correlation coefficient is 0.75.
From R 1 2 And R is 2 2 All are smaller than 0.75, which means that in the range of roughness of 0.8-50.0, the linear relation between corrosion resistance Rp and corrosion resistance time T is poor, the linear relation between contact angle theta and corrosion resistance time T is also poor, and the number of standard samples is larger than 5, soThe corrosion resistance evaluation model needs to be constructed in a piecewise fitting mode.
(2) Segment fitting
From the data in Table 1, it can be calculated that the salt spray test corrosion resistance time and the electrochemical corrosion resistance linear correlation coefficient A of the No. 1 data set to the No. 3 data set 1 2 0.9838 the linear correlation coefficients A corresponding to data sets 1 to 4 2 2 0.3802. Due to A 1 2 Greater than 0.75, and A 2 2 Less than 0.75, data set No. 3 is used as segment data set No. 1.
Linear correlation coefficient A of corrosion resistance time and electrochemical corrosion resistance of salt spray test in data set 3 to data set 5, data set 3 to data set 6 3 2 0.0002, A 4 2 0.1737 due to A 3 2 And A 4 2 All are smaller than 0.75, collecting the linear correlation coefficient B of the corrosion resistance time and the contact angle of the salt spray test in the No. 3 data set to the No. 5 data set and the No. 3 data set to the No. 6 data set 1 2 And B 2 2 ，B 1 2 0.7781, B 2 2 0.603. Due to B 1 2 Greater than 0.75, and B 6 2 Less than 0.75, the data set No. 5 is used as the segment data set No. 2.
The number of samples from the data set 5 to the data set 7 is small, and segmentation cannot be performed, so the data set 7 is used as the data set 3 for segmentation, namely the data set 5 to the data set 7 are directly used as a fitting segment.
And performing linear fitting on each fitting segment according to the segmentation result. The specific fitting steps are as follows:
(1) first fitting section: fitting with the corrosion resistance Rp and the corrosion resistance time T of the data sets 1 to 3 to obtain the following relational expression (3): t= 21.862 ×10 -7 X Rp+525.1, corresponding R 3 2 = 0.9838. Fitting is carried out according to the contact angle theta and the corrosion resistance time T of the data sets from 1 to 3, and the following relational expression (4) is obtained: t= -4.0225 x θ+1021.6, pairR is correspondingly 4 2 = 0.6563. Due to R 3 2 Greater than 0.75, R 4 2 Since the corrosion resistance Rp is smaller than 0.75, in the range of the roughness of 0.8-3.2, the corrosion resistance Rp and the corrosion resistance time T have a good linear relationship, and the relation (3) is used as a corrosion resistance relation of the first fitting section.
(2) Second fitting section: fitting with the corrosion resistance Rp and the corrosion resistance time T of the data sets of numbers 3 to 5 to obtain the following relational expression (5): t= -1.8405 x 10 -7 X Rp+592.45, corresponding R 5 2 =0.0002. Fitting is carried out according to the contact angle theta and the corrosion resistance time T of the data sets from 3 to 5, and the following relational expression (6) is obtained: t= 7.2617 ×θ+43.048, corresponding R 6 2 = 0.7781. Due to R 5 2 Less than 0.75, R 6 2 In the section with the roughness of 3.2-12.5, the contact angle theta and the corrosion resistance time T have a good linear relation, and the relation (6) is used as a corrosion resistance relation of the second fitting section.
(3) Third fitting section: fitting with the corrosion resistance Rp and the corrosion resistance time T of the data sets of No. 5 to No. 7, the following relational expression (7) is obtained: t= -228.57 x 10 -7 X Rp+1940, corresponding R 7 2 = 0.7033. Fitting is carried out according to the contact angle theta and the corrosion resistance time T of the data sets from 3 to 5, and the following relational expression (8) is obtained: t= 53.689 ×θ -3082.9, corresponding R 8 2 = 0.6746. From R 7 2 And R is 8 2 All are smaller than 0.75, which means that in the range of roughness of 12.5-50.0, the contact angle theta and corrosion resistance Rp are relatively poor in linear relation with corrosion resistance time T, so that the contact angle theta and corrosion resistance Rp are required to be adopted to simultaneously perform binary linear fitting on the corrosion resistance time T, thereby obtaining a relation (9) T=39.375×theta-317.648 ×10 -7 And x Rp-988.13, and taking the corrosion resistance relation of the third fitting section.
According to each corrosion resistance relation and the corresponding roughness interval, a corrosion resistance evaluation model shown in table 2 is constructed.
TABLE 2
| Roughness of | Relation between corrosion resistance |
| 0.8μm～3.2μm | T＝21.862×10 -7 ×Rp+525.1 |
| 3.2μm～12.5μm | T＝7.2617×θ+43.048 |
| 12.5μm～50.0μm | T＝39.375×θ-317.648×10 -7 ×Rp-988.13 |
(4) Performance test of a sample to be tested
The contact angles, electrochemical corrosion resistance and roughness of the metal substrate of a plurality of samples to be tested (designated as 1# to 4# samples to be tested) were obtained by the same test method as the standard sample, and specific results are shown in table 3.
(5) Corrosion resistance evaluation of test sample
And (3) obtaining a corrosion resistance relation according to the roughness measured in the step (4) and the roughness interval shown in the table 2, wherein the corrosion resistance relation is specifically shown in the table 3. The contact angle and/or the electrochemical corrosion resistance were taken into the confirmed relation to obtain a salt spray test corrosion resistance time T, as shown in table 3.
TABLE 3 Table 3
The predicted corrosion resistance time in table 3 is calculated by substituting the contact angle and corrosion resistance data of each sample to be measured into the relational expression in table 2. The actual measured corrosion resistance time in table 3 is a salt spray test according to national standard GB/T10125 for each sample to be tested, and the standard sample is scribed before the test. And detecting the expansion and corrosion distance at the scribing position every 24 hours, and recording the time when the expansion and corrosion distance is larger than or equal to 2mm for the first time, wherein the time is taken as the actually measured corrosion resistance time. As can be seen from Table 3, the predicted corrosion resistance time obtained by the corrosion resistance evaluation model of the present application is similar to the measured corrosion resistance time of the sample to be tested, which indicates that the present application can evaluate the corrosion resistance of the sample to be tested more accurately. The corrosion resistance of samples 1# to 4# to be tested can be evaluated by a person skilled in the art according to the corrosion resistance time of the salt spray test obtained in table 3.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. The corrosion resistance evaluation method is characterized by comprising the following steps of:
acquiring contact angles, electrochemical corrosion resistance and corrosion resistance time of the salt spray test of N standard samples; the standard samples comprise metal substrates and coatings arranged on the metal substrates, and the roughness of the metal substrates of the standard samples is different, wherein N is more than or equal to 3, and N is an integer;
taking the contact angle, the electrochemical corrosion resistance and the salt spray test corrosion resistance time of the same standard sample as a group of data sets, and constructing a corrosion resistance evaluation model of a sample to be tested according to N groups of data sets of the N standard samples; the sample to be tested comprises a metal substrate and a coating arranged on the metal substrate;
acquiring the roughness of a metal substrate of the sample to be detected, the contact angle of the sample to be detected and the electrochemical corrosion resistance of the sample to be detected; and
And obtaining the corrosion resistance evaluation result of the sample to be tested according to the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be tested, the contact angle of the sample to be tested and the electrochemical corrosion resistance of the sample to be tested.
2. The corrosion resistance evaluation method according to claim 1, wherein the roughness of the metal substrate of each of the standard samples satisfies the following relationship:
and marking N standard samples as 1 st to N th standard samples in sequence from the roughness to the roughness, wherein the ratio of the N standard sample to the roughness of the N-1 st standard sample is 1.8-2.5, N is more than 1 and less than or equal to N, and N is an integer.
3. The method for evaluating corrosion resistance according to claim 2, wherein the roughness of the metal substrate of each of the standard samples is independently selected from 0.8 μm to 100 μm.
4. The method for evaluating corrosion resistance according to claim 3, wherein the number of the standard samples is 7, and the roughness of the metal substrate in each of the standard samples is 0.8 μm, 1.6 μm, 3.2 μm, 6.3 μm, 12.5 μm, 25.0 μm, and 50.0 μm, respectively.
5. The method for evaluating corrosion resistance according to claim 1, wherein N of the standard samples and the sample to be tested are metal substrates of the same material;
and/or forming the coating on the metal substrates of the N standard samples and the sample to be tested by adopting the same electrophoresis process.
6. The method according to any one of claims 1 to 5, wherein the step of constructing a corrosion resistance evaluation model of a sample to be measured from N sets of the data sets of the N standard samples, comprises:
according to the electrochemical corrosion resistance and the corrosion resistance time of each salt spray test in the N groups of data sets, a first relation and a linear correlation coefficient R of linear fitting between the electrochemical corrosion resistance and the corrosion resistance time of the salt spray test are obtained 1 2 ；
Obtaining a second relation and a linear correlation coefficient R of linear fitting between the contact angle and the corrosion resistance time of the salt spray test according to the contact angles and the corrosion resistance time of the salt spray test in the N groups of data sets 2 2 ；
According to R 1 2 And R is 2 2 And determining a corrosion resistance evaluation model.
7. The method for evaluating corrosion resistance according to claim 6, wherein, based on R 1 2 And R is 2 2 A step of determining a corrosion resistance evaluation model, comprising:
if R is 1 2 Not less than a and R 2 2 < a, taking the first relation as the corrosion resistance evaluation model;
if R is 2 2 Not less than a and R 1 2 < a, using the second relation as the corrosion resistance evaluation model;
if R is 1 2 Not less than a and R 2 2 Not less than a, R 1 2 And R is 2 2 The corresponding relation of the relatively larger one of the three is used as the corrosion resistance evaluation model;
if R is 1 2 < a and R 2 2 A, performing binary fitting or piecewise fitting on the N groups of data sets to obtain the corrosion resistance evaluation model;
wherein a is a preset linear correlation coefficient.
8. The method for evaluating corrosion resistance according to claim 7, wherein if R 1 2 ＜a，R 2 2 A is more than or equal to 3 and less than or equal to 5, and binary fitting is carried out on the N groups of data sets;
if R is 1 2 ＜a，R 2 2 And (3) a, wherein N is more than or equal to 5, and performing piecewise fitting on the N groups of data sets.
9. The corrosion performance evaluation method of claim 8, wherein the step of performing a binary fit to said N sets of data sets comprises:
and obtaining a third relation of linear fitting among the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test according to the electrochemical corrosion resistance, the contact angle and the corrosion resistance time of the salt spray test in the N groups of data sets, and taking the third relation as the corrosion resistance evaluation model.
10. The method according to any one of claims 1 to 5 and 7 to 9, wherein the step of obtaining the corrosion resistance evaluation result of the sample to be measured based on the corrosion resistance evaluation model, the roughness of the metal substrate of the sample to be measured, the contact angle of the sample to be measured, and the electrochemical corrosion resistance of the sample to be measured, comprises:
acquiring a corresponding corrosion resistance relation according to the roughness of the metal substrate of the sample to be detected;
according to the acquired corrosion resistance relation, combining the contact angle and the electrochemical corrosion resistance of the sample to be tested to obtain the salt spray test corrosion resistance time of the sample to be tested;
and according to the corrosion resistance time of the salt spray test of the sample to be tested, obtaining the corrosion resistance evaluation result of the sample to be tested.
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