JB/T 8424-1996 Test method for natural seawater corrosion of metal coverings and organic coatings
Some standard content:
JB/T8424-1996
This standard mainly refers to the American Society for Testing and Materials standard ASTMG52--1988 "Standard Method for Exposure and Evaluation of Metals and Alloys in Surface Seawater", and refers to GB5776-~1986 "Methods for Conventional Exposure Corrosion Test of Metal Materials in Surface Seawater" and GB6384-1986 "Methods for Seawater Corrosion Test of Metal Materials for Ships and Marine Use in Natural Environments". Some technical parameters (such as 3.3 and 4.1 of this standard) are formulated based on the situation of seawater tests in my country, as well as GB5776 and GB6384. Since ASTMG52, GB5776 and GB6384 are only applicable to metal materials, the contents of Chapter 5 and Chapter ? of this standard are formulated based on the characteristics of metal coatings and organic coatings and relevant standards.
This standard shall be implemented from July 1, 1997. This standard is proposed and managed by the National Technical Committee for Standardization of Metal and Non-metallic Coatings. The originating unit of this standard: Wuhan Institute of Materials Protection, Ministry of Machinery Industry. The main drafters of this standard are Xia Chunlan, Zhang Lanping and Xiao Yide. 1083
Fan Pu
Standard of the Machinery Industry of the People's Republic of China
Metallic Coverings and Organic Coatings
Natural Seawater Corrosion Test Methods
JB/T 8424--1996
This standard specifies the corrosion test methods for metallic coverings and organic coatings under the conditions of full immersion, tidal range and splash in natural seawater. This standard is applicable to metallic coverings and organic coatings. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB6461-1986 Rating of electroplated samples after corrosion tests on metal coatings with cathode as substrate GB9277.1~9277.5-1988 Evaluation of aging of paint coatings GB12335-1990 Rating of samples after corrosion tests on metal coatings with anodic properties as substrate JB/T6094-1991 Preparation, cleaning and evaluation of magic corrosion samples 3 Test conditions
3.1 Test location
The test location should meet the following requirements:
a) The test location should be selected in an area with representative natural seawater environment; b) The seawater environmental factors are stable and there are no industrial pollution sources; c) There is no large wave impact, but there is natural flow caused by tides, and the flow rate is below 1 m/s; d) There is a certain temperature difference and marine organisms with seasonal changes, and there is no freezing period; e) There are safety protection measures to prevent storm attacks. 3.2 Measurement of test conditions
The following marine environmental factors should be measured and recorded regularly: a) seawater temperature;
b) seawater salinity, conductivity and pH value; c) concentration of dissolved oxygen in seawater,
d) seawater flow velocity;
e) types and contents of pollutants in seawater
f) major marine organisms;
g) for exposure under tidal range and splash conditions, factors such as atmospheric temperature, humidity, sunshine duration and intensity, wind direction, wind speed, and atmospheric pollution should be measured.
3.3 Test types
Depending on the test purpose, the following test types can be used. Approved by the Ministry of Machinery Industry on September 3, 1996
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Implemented on July 1, 1997
3.3.1 Full immersion test
JB/T 8424\u20141996Www.bzxZ.net
For fixed devices, the specimen shall be no less than 0.8m from the seabed and no less than 0.2m from the water surface at the lowest tide. For floating devices, the specimen shall be no less than 0.2m from the water surface.
3.3.2 Tidal range test
The specimen shall be between the average mid-tide level and \u00b10.3m. 3.3.3 Splash test
The splash zone specimen shall be hung in the most corrosive area of \u200b\u200bthe test facility (this area can be determined by the corrosion rate of the metal specimen hanging piece) and shall be exposed to sunlight.
4 Test equipment
4.1 Test facilities
a) Fixed type: such as fully immersed cage, tidal platform and pier pier hanging, etc.; b) Floating type: such as floating Xiao, floating device set up sample frame, and meet the requirements of 3.3.1 or 3.3.2; c) For splash test, fence type hanging rack is recommended. 4.2 Sample frame
The sample frame should be made of materials that are resistant to seawater corrosion and do not affect the corrosion behavior of the sample. The frame shall not be replaced during the entire test. The frame can be made of metal material, with plastic or nylon spacer insulation, or it can be made of reinforced plastic or treated wood. The sample frame can be protected when necessary to ensure the normal test. 4.3 Fixation and placement of samples
4.3.1 Keep electrical insulation between the sample and the frame, and between the samples to avoid the formation of galvanic corrosion cells. Porcelain or plastic can be used as insulation, and the sample can be installed with plastic bolts and nuts.
4.3.2 To avoid obstruction of marine organisms between samples and ensure smooth water flow, sufficient distance should be maintained between samples. The distance between the general sample and the frame should not be less than 50mm, and the distance between the main sample surfaces should not be less than 100mm. 4.3.3 To avoid artificial crevice corrosion, the contact area between the clamps that fix the sample and the sample should be as small as possible, and the size of the crevice caused by the contact should be as consistent as possible.
4.3.4 For splash test, all samples should be exposed to the same conditions as much as possible. 4.3.5 Copper and copper alloy samples should be placed separately from other gold coating samples and keep a certain distance. 4.3.6 For tidal range and full-diffusion samples, the main test surface should be perpendicular to the horizontal plane and parallel to the water flow direction. 5 Samples and their preparation
5.1 Sample type
Specimen types are metal coatings and organic coatings. Specially prepared flat specimens or product specimens can be used. If the sample shape is complex, a sample holder suitable for them must be designed.
5.2 Specimen size
The recommended size of the flat specimen is (300~~350) mm\u00d7(150~~250) mm\u00d7(2~~3) mm. For specimens for special test purposes, if there are special requirements, they can be implemented as required. 5.3 Number of specimens
In any batch test, the number of specimens should be determined according to the type of specimen, the number required to evaluate specific physical properties, and the number expected to be taken out regularly during the test. For the evaluation of a certain project, the number of specimens of the same type shall not be less than three. 5.4 Specimen marking
The specimen marking must be clearly recognizable throughout the test. The best method is to punch marking holes on the specimen before plating (coating). The marking should indicate the test material, test location, test conditions, test cycle, and parallel specimen serial number. Make the positioning holes for the specimen according to the test device. 5.5 Preparation of samples
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5.5.1 The surface of the sample substrate should be cleaned, and the mechanical rust removal level of the steel surface should be greater than or equal to Sa2.5 in SIS05-5900. The plating (coating) process of the metal coating and organic coating should meet the relevant technical requirements. 5.5.2 Before the test, measure the relevant parameters of the sample surface coating, check the appearance of the sample, and record the surface defects and man-made damage. 5.5.3 When necessary, weigh the original mass of the sample to an accuracy of \u00b11mg; measure the original size of the sample to an accuracy of \u00b10.1mm. 5.6 Storage of samples
Before the test, place the sample in a sealed desiccator or seal it in a vacuum plastic bag containing a desiccant. 5.7 Comparison samples
If you need to compare the test results of samples in different sea areas or at different times, you can place a comparison sample (such as cold-rolled steel plate, etc.) next to the sample. 6 Test Procedure
6.1 Prepare the specimens according to Chapter 5.
6.2 Fix and place the specimens according to 4.3, and draw a specimen frame map. 6.3 The recommended test start time is September to October each year, and the test cycle is 1, 2, 5, 1020 years, and the shortest is 1 year. 6.4 Check the specimens regularly according to the test requirements, generally once a year, and observe and record the corrosion and marine biological adhesion conditions. During the inspection, the corrosion products and the marine biological adhesion layer must not be damaged, and the specimen frame must not be out of water for more than 30 minutes. 6.5 Regularly measure and record the marine environmental factors described in 3.2. 6.6 Take out the specimens according to the predetermined test cycle, observe and record the corrosion conditions and marine biological adhesion conditions of the specimens (such as the type, quality, thickness, etc. of marine biological adhesion).
6.7 Use a plastic or wooden scraper to remove marine organisms attached to the sample, and use a soft brush to wash away the deposited dirt on the sample without damaging the coating. Inspect the sample and evaluate the test results according to Chapter ?. 7 Evaluation of test results
After removing the marine organisms attached to the sample, inspect and evaluate the corrosion of the sample according to the following methods: a) For cathodic metal coatings, evaluate according to the method specified in GB6461; b) For anodic metal coatings, evaluate according to the method specified in GB12335; c) For organic coatings, evaluate according to the methods specified in GB9277.1~9277.5. d) For samples that need to obtain corrosion rates, remove the corrosion products according to the method described in B/T6094 and calculate the corrosion rate. 8 Test report
The test report should include the following contents.
8.1 Test specimens
a) Name, brand, composition and metallographic structure of the base material; b) Surface treatment of the base material before coating (coating); c) Type, material and actual thickness of the coating; d) Post-treatment method of the coating (such as sealing, surface coating, etc.); e) Basic properties of the coating (such as bonding strength, porosity, hardness, ductility, etc.); f) Number, original mass and original size of the test specimens; g) Appearance of the test specimens before the test.
8.2 Test conditions
a) Test location:
b) Data of marine environmental factors measured regularly; c) Test type;
d) Method of fixing and placing the test specimens.
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Test results
a) Test start and end time;
b) Intermediate inspection date and inspection results;
JB/T 8424\u20141996
c) After the test, the appearance of the sample corrosion morphology description and corrosion rating; d) Sample corrosion rate and sample cleaning method after the test; e) If necessary, attach photos of the sample before and after the test. 1087
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