GB 5210-1985 Determination of coating adhesion - Pull-off method

This standard is applicable to the quantitative determination of adhesion between single-layer or composite coatings and substrates or between coatings. GB 5210-1985 Determination of adhesion of coatings Pull-off method GB5210-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of adhesion of coatings-pull-off test
Determination of adhesion of coats-pull-off testGB5210-85
Approved and issued by the State Bureau of Standards
1986-03-01 Implementation
1985-07-16 Approved
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This standard is applicable to the quantitative determination of adhesion between single-layer or composite coatings and substrates or between coatings. This standard refers to the international standard ISO4624-1978 "Paints and varnishes-Pull-off test method for adhesion". 1 Definition
The adhesion determined by the pull-off method refers to the force required to determine the adhesion between coatings or between coatings and substrates when a vertical and uniform pulling force is applied to the bonding surface of the sample at a specified speed. It is expressed in kg/cm2. 2 Setting
2.1 Tensile testing machine
The load selection of the tensile testing machine should be adapted to the breaking load of the specimen. The fixture used in the test should be able to center and fix the specimen, and the testing machine should increase the tension steadily and act vertically on the surface of the test column.
2.2 Test column
The test column used in the test is made of metal (steel, iron, aluminum, etc.). The diameter of the test column is 20mm, and the height should not be less than half of its own diameter. Its plane should be perpendicular to the long axis of the test column. As shown in Figure 1.
2.3 Centering device
When operating according to 3.3 and 3.4, the coaxial arrangement of the fixed specimen can be guaranteed. As shown in Figure 2.
Figure 2 Example of centering device for 20mm diameter test column 1-butt test sample; 2-combined test sample; 3-centering pin 3 Preparation of test sample
0.01~0.02
Figure 1 Test column
3.1 Test sample
The test sample is a butt joint or combination of two metal test columns. The materials used for the metal test column and its surface treatment should be the same as the practical substrate. Paint the surface of one test column according to the technical conditions of its corresponding coating product. Use adhesive to bond with another test column. Its composition and shape are shown in Figure 3. 3.2 Preparation and drying of coating
The preparation and drying of the coating to be tested should be carried out according to the conditions specified in the technical conditions of its corresponding coating product or the coating construction process instructions.
3.3 Bonding of the test specimenbZxz.net
Evenly apply a thin layer of adhesive on the unpainted test column. It can be bonded coaxially with the device in Figure 2, together with the centering device, and cured according to its drying process requirements. Before curing, wipe off the excess adhesive with a trace amount of solvent. 3.4 Combined test specimen
Combined test specimens (see Figure 4) are suitable for materials that are not suitable for processing into test columns, such as deformable substrates, composite materials and glass. When preparing the sample, a piece should be cut from the painted substrate as a test piece (a round piece with a minimum diameter of 30mm or a square test piece with a side length of 30mm). Evenly apply a thin layer of adhesive on the surface of two clean test columns, and use the centering device to make the upper and lower test columns and the test piece concentrically docked (see Figure 2, 2). Keep it still during curing. Car
Adhesive
Figure 3 Butt test specimen
Adhesive
Single-sided or double-sided
, painted test piece
Figure 4 Combined test specimen
After curing, use a sharp knife to cut through the cured adhesive and paint layer along the perimeter of the test column to reach the substrate. 3.5 Adhesive
The preparation and use of adhesives shall comply with the provisions of the relevant technical standards. The minimum amount of adhesive should be used during coating so that a firm, continuous and uniform bonding surface is produced when the test specimen is combined. Note: ① In most cases, an adhesive with α-cyanoacrylate as the main component or a two-component adhesive with a ratio of E-44 epoxy resin: TY-200 polyamide = 1:1 is used.
② In order to improve the bonding strength of the bonded test column, the surface of the dried coating to be tested and the test column can be lightly polished with fine sandpaper. ③ When combining the test specimens, if it is expected that the unpainted side of the test piece will not bond well with the test column, both sides of the test piece can be painted in advance. Test conditions
The test environment should be maintained at: temperature 25±1℃, relative humidity 60%~70%. Instructions for use:
① The international standard stipulates that "a cutting device should be used to cut straight through the substrate along the edge of the test column." In this standard, a sharp knife can be used. 513
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5 Test steps
5.1 Place the prepared specimen into the upper and lower clamps of the tensile machine and adjust them to the center so that the cross section is evenly subjected to tension. 5.2 The clamps are pulled apart at a tensile speed of 10mm/min until they are broken. Record the load value of the specimen being pulled apart and observe the form of failure on the cross section.
6 Test results
6.1 Calculation of results
The adhesion of the coating is calculated as follows:
Where F is the adhesion of the coating, kg/cm2; G is the force at which the specimen is pulled apart and broken. Load value at failure, kg; S——Cross-sectional area of ​​the test column coated with the tested coating, cm2. 6.2 Failure form ①
6.2.1 Adhesion failure: Destruction between the coating and the substrate, or the interface of the composite coating, represented by A. 6.2.2 Internal sudden failure The coating itself is damaged, represented by B. 6.2.3 The adhesive itself is damaged or the topcoat of the tested coating is partially torn, which indicates that the adhesion between the coating and the substrate or the interface adhesion between the coatings is greater than the obtained value, represented by C. 6.2.4 Adhesive failure: The adhesive is detached from the unpainted test column, or completely detached from the topcoat of the tested coating, represented by D. When the failure form is A, B or C, the measurement result meets the requirements of the adhesion test. If two or more failure forms appear, the percentage of the damaged area should be indicated. Score, more than 70% is valid. When D appears, the selection, process and quality of the adhesive should be inspected or replaced. When C appears, it means that the strength of the adhesive cannot meet the requirements. The material with higher adhesive strength can be replaced to quantitatively express the adhesion of the coating. 6.3 Test error?
Each group of tested coating specimens should have no less than 5 pairs, and the arithmetic mean of at least 3 pairs should be taken as the test result. The error between the F value of each pair of specimens and the arithmetic mean should not exceed ±15% to be valid. Note: The test results are not only related to the performance of the coating, but also affected by the type of substrate, surface treatment method, coating process, environmental temperature and humidity, whether the tested coating is completely dry and other factors. Representation of results
The test results are expressed in terms of adhesion and failure form. The test report should include the following contents: a. Name, brand, batch number and source of the tested coating; Instructions for use: ① International standards specify seven codes for the failure forms. This standard considers that four codes can be used to express the failure forms according to the verification results. ② The test error is not specified in the international standard. 514
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b. Name and brand of the test column and adhesive; c. Process conditions for preparing the specimen; d. Number and quantity of the specimen; e. Temperature and humidity of the environment during the test; f. Model, load and loading speed of the test tensile machine; g. Destruction load, failure form, adhesion and error of the coating of the specimen; h. Deviations and abnormal phenomena that occurred during the test; 1. Test date and test personnel.
Additional Notes:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the National Technical Committee for Standardization of Paints and Pigments. This standard was drafted by the 621st Institute of the Ministry of Aviation Industry of the People's Republic of China. The main drafters of this standard are Li Guirong and Yang Hezheng. 515
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