Method for comprehensively evaluating failure of organic coating

Abstract

The invention provides a method for comprehensively evaluating the failure of an organic coating. So far, a comprehensive evaluation method for organic coatings with multiple failure modes is still lacked. According to the method, based on eight common failure modes of the organic coating and the relative importance of the failure of the coating, a pairwise comparison matrix is established based on the principle of an analytic hierarchy process, the weight coefficients of different failure modes are solved, and finally, the comprehensive evaluation method for the failure of the organic coating is quantitatively constructed through a linear weighting method. And experimental verification is consistent with the actual situation.

Description

Technical Field

[0001] The invention belongs to the field of organic coatings. Background Art

[0002] Organic coatings have been widely used in the field of engineering corrosion control due to their economic and convenient construction advantages. Organic coatings mainly play their protective role by shielding and preventing direct contact between metals and corrosive media. The maintenance of their protective performance is closely related to their integrity. In actual processes, organic coatings often fail in multiple modes in advance due to the coupling of multiple environmental load factors, which ultimately causes serious consequences such as corrosion of the substrate and mechanical damage. Therefore, it is very important to quickly and accurately judge the degree of aging of organic coatings. At present, the evaluation methods for organic coating failure are mainly divided into two categories: electrochemical testing and non-electrochemical testing. Among them, although electrochemical testing has high detection accuracy, it has high requirements for the test environment. Although non-electrochemical testing methods have the advantage of convenient detection, they only detect some simple failure modes of organic coatings according to relevant standards. However, there is still a lack of comprehensive evaluation methods for organic coatings with multiple failure modes. Therefore, it is very urgent to develop a new method for evaluating organic coatings that is simple, fast and highly accurate.

[0003] The present invention proposes eight failure modes based on organic coatings, and evaluates the eight failure modes separately according to relevant standards. Then, using the principle of hierarchical analysis, a pairwise comparison matrix is ​​constructed to solve the weighted coefficients of the eight failure modes, and based on linear weighting, a method for comprehensively evaluating organic coatings is generally used, thereby providing a quantitative basis for the comprehensive evaluation of organic coating system failure. Summary of the invention

[0004] In view of the diversity of failure modes of organic coatings, the present invention is based on the eight common failure modes of organic coatings and the relative importance of coating failure. Based on the principle of hierarchical analysis, a pairwise comparison matrix is ​​established to solve the weight coefficients of different failure modes. Finally, a method for comprehensive evaluation of organic coating failure is quantitatively constructed through a linear weighted method.

[0005] The comprehensive evaluation method for failure of organic coatings has the following steps:

[0006] 1) Select n common failure modes of organic coatings as evaluation indicators, and rank the eight failure modes from low to high according to the importance of each mode to the failure of organic coatings.

[0007] 2) According to the relative importance of the above failure modes, an n-order pairwise comparison matrix is ​​established, that is,

[0008]

[0009] where a ij represents the importance of the i-th element relative to the j-th element. ij When a > 1, it means that the i element is more important than the j element. As the value increases, the importance of the i element compared to the j element gradually increases. ij When <1, it means that the j element is more important than the i element. As the value decreases, the importance of the j element relative to the i element gradually increases.

[0010] 3) Solve the consistency index CI of the matrix according to formula (1).

[0011] CI=(λ max -n) / (n-1)(1)

[0012] In step 3) max is the maximum eigenvalue of the matrix, and n is the order of the matrix. In this model, there are 8 failure modes selected, and the matrix obtained is of 8th order, so n is 8 at this time.

[0013] 4) Solve the consistency ratio according to formula (2).

[0014] CR=CI / RI (2)

[0015] 5) Solve the weights of different factors according to formula (3).

[0016]

[0017] 6) Refer to GB / T 1766 to conduct a single evaluation of the failure mode of the coating sample and obtain its evaluation value. 7) Substituting the obtained single evaluation value and weight into formula (4) can obtain the comprehensive evaluation value of different coating samples.

[0019]

[0020] Where m is the number of indicators. In this model, there are eight indicators in total, so the weights of 8 indicators are obtained. So m should be 8 here.

[0021] In step 4), the reference value of the random consistency ratio is shown in Table 1. According to the order of the matrix, the corresponding RI value is selected. Only when the consistency ratio is less than 0.1, the subsequent steps can be continued. Otherwise, the matrix needs to be adjusted.

[0023] Table 1 Random consistency ratios corresponding to matrices of different orders

[0024]

[0025] In step 6), the evaluation criteria for different failure modes are shown in Tables 2 and Figure 1 .

[0026] Table 2 Judgment basis of different failure mode levels

[0027]

[0028] After the circle drawing test, Figure 1 If the black part in the middle is peeling off, the corresponding number is the adhesion failure level.

[0029] In Table 2 of step 6), the criteria for judging powdering, cracking and blistering are based on GB / T 1766.

[0031] In step 7), all evaluation results are divided into 0-5 levels. Among them, 0-0.9 means that the coating protection effect is in a good state; between 1.0 and 1.9, it means that the coating is in a good state; 2.0-2.9 means that the coating protection effect is average, and it should be used with caution; 3.0-3.9 means that the coating protection effect is poor, and the use risk is greater; 4.0-5.0 means that the coating has basically no protection effect and cannot be used. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a diagram for determining adhesion failure levels. DETAILED DESCRIPTION

[0035] Taking the marine atmospheric environment as an example, this method is used to comprehensively evaluate the failure degree of organic coatings: 1) Eight common failure modes such as coating thinning, discoloration, gloss loss, adhesion, cracking, bubbling, powdering, and peeling are selected.

[0036] See failure mode as an evaluation indicator. According to the importance of each failure mode to the failure of organic coatings, they are ranked from low to high, namely, loss of gloss, thinning, discoloration, chalking, adhesion, blistering, cracking and peeling.

[0037] 2) According to the relative importance of the above eight failure modes, an 8-order pairwise comparison matrix is ​​established, see Table 3.

[0038] Table 3 Comparison of the importance of different key evaluation indicators

[0039]

[0040]

[0041] 3) According to formula (1), the CI value of this matrix is ​​0.0507.

[0042] 4) Substituting it into formula (2) to calculate the consistency ratio is 0.036<0.1.

[0043] 5) According to formula (3), the weight coefficients of different influencing factors are calculated, and the calculation results are:

[0044] 0.0180, 0.0310, 0.0510, 0.0760, 0.1400, 0.1800, 0.2260 and 0.2780.

[0045] 6) With reference to relevant standards, the eight failure modes of the coating are evaluated separately and assigned values ​​according to 5 levels, namely 0, 1, 2, 3, 4, and 5. Among them, 0 corresponds to a new coating put into use, as listed in Table 4.

[0046] Table 4 Rating of individual indicators of coating after accelerated test

[0047]

[0048] 7) Substituting the individual scores in Table 4 and the weight coefficients calculated in step 5 into formula (4) can obtain the final coating damage evaluation value, see Table 5.

[0049] Table 5 Comprehensive evaluation values ​​of different samples

[0050]

[0051] 8) According to the evaluation results, it can be seen that the comprehensive score of sample No. 1 is between 1.0 and 1.9, indicating that the coating protection effect is good; while the comprehensive score of samples No. 2 and No. 3 is between 0 and 0.9, indicating that the coating protection effect is good.

Claims

1. A method for comprehensive evaluation of organic coating failure, characterized in that: The following steps are involved: 1) Select n failure modes of organic coating as evaluation indicators, and rank the eight failure modes from low to high according to the importance RI of each mode to the failure of organic coating, as shown below: 2) According to the relative importance of the above failure modes, an n-order pairwise comparison matrix is ​​established, that is, where a ij Represents the importance of the i-th element relative to the j-th element; when a ij >1, it means that the i element is more important than the j element. As the value increases, the importance of the i element compared to the j element gradually increases. ij When <1, it means that the j element is more important than the i element. As the value decreases, the importance of the j element relative to the i element gradually increases. 3) Solve the consistency index CI of the matrix according to formula (1); C.I.=(λ max -n) / (n-1)(1) In step 3) max is the maximum eigenvalue of the matrix, n is the order of the matrix; In this model, there are 8 selected failure modes, and the resulting matrix is ​​of order 8, so n is 8; 4) Solve the consistency ratio according to formula (2); CR=CI / RI (2) 5) Solve the weights of different factors according to formula (3); 6) Refer to the single evaluation of the failure mode of the coating sample and obtain its evaluation value; Failure modes include chalking, cracking, and blistering, as well as gloss loss, thinning, flaking, and discoloration; 7) Substituting the obtained single evaluation value and weight into formula (4) can obtain the comprehensive evaluation value of different coating samples; Where m is the number of indicators, and m is 8.

2. The method according to claim 1, characterized in that: Step 6) Powdering, cracking and The determination of blistering shall be based on the standard GB / T 1766.

3. The method according to claim 1, characterized in that: In step 7), all evaluation results are divided into 0-5 levels; among which 0-0.9 represents that the coating protection effect is in a good state; When it is between 1.0 and 1.9, it means that the coating is in good condition; 2.0 to 2.9 means that the coating has average protective effect and should be used with caution; 3.0 to 3.9 means that the coating has poor protective effect and the risk of use is greater; 4.0 to 5.0 means that the coating has basically no protective effect and cannot be used.

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