This standard specifies a test method for the penetration porosity test of thermal spray coatings. This standard is applicable to the test of various thermal spray coatings on steel substrates that do not react chemically with sodium chloride and potassium ferrocyanide solutions, such as aluminum, tin, lead, copper and other non-ferrous metals, plastics and ceramics. JB/T 7509-1994 Test method for porosity of thermal spray coatings Iron reagent method JB/T7509-1994 Standard download decompression password: www.bzxz.net
This standard specifies a test method for the penetration porosity test of thermal spray coatings. This standard is applicable to the test of various thermal spray coatings on steel substrates that do not react chemically with sodium chloride and potassium ferrocyanide solutions, such as aluminum, tin, lead, copper and other non-ferrous metals, plastics and ceramics.

Mechanical Industry Standard of the People's Republic of China
JB/T7509-94
Test Method for Porosity of Thermal Spray CoatingsWww.bzxZ.net
Iron Reagent Method
Published on October 25, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on October 1, 1995
Mechanical Industry Standard of the People's Republic of China
Test Method for Porosity of Thermal Spray Coatings
Iron Reagent Method
1 Subject Content and Scope of Application
This standard specifies a test method for penetrating porosity test of thermal spray coatings. JB/T7509-94
This standard is applicable to the testing of various thermal spray coatings on steel substrates that do not react chemically with sodium chloride and potassium ferrocyanide solutions, such as non-ferrous metals such as aluminum, tin, lead, copper, plastics and ceramics, etc. 2 Test Principle
Thermal spray coatings are generally porous. If the coating has through pores from the surface to the substrate, the test solution penetrates through the through pores into the substrate and reacts chemically with the iron. The reactants migrate to the test paper in close contact with the coating surface. When the test paper is immersed in the potassium ferrocyanide solution, blue spots appear where there are iron ions. These blue spots indicate that there are pores at the corresponding positions of the coating. The number of spots indicates the amount of pores in the coating.
3 Specimen
The specimen can be a workpiece that has been sprayed, or a flat specimen prepared by spraying with the same process and materials as the workpiece. The test surface area should generally be between 25 and 100 cm2.
4 Preparation of test solution
4.1 Test supplies
All chemicals used are analytically pure. The test water is distilled water. The test paper should have a certain strength when wet, such as filter paper. The paper should be kept clean and dry before the test, especially without being contaminated by iron ions. 4.2 Sodium fluoride solution
Dissolve 50g sodium chloride and 1g non-ionic wetting agent, such as emulsifier OP-10, in 1L distilled water, and adjust the pH to 6±0.2 with hydrochloric acid or sodium hydroxide for later use.
4.3 Sodium chloride gel solution
Dissolve 50g sodium oxide, 50g gelatin or agar, and 1g non-ionic wetting agent in 1L distilled water not lower than 85℃, and adjust the pH to 6±0.2 with hydrochloric acid or sodium hydroxide. The solution will gel after cooling. When using, it needs to be heated to 35-50℃. 4.4 Potassium ferrocyanide solution
Dissolve 10g potassium ferrocyanide in 1L distilled water, and adjust the pH to 6±0.2 with hydrochloric acid or sodium hydroxide. Note: The solution should generally be prepared as needed. If the solution needs to be stored, it should be placed in a brown glass bottle and sealed in a dark place. If the solution changes color or contains suspended matter, stop using it.
5 Test steps
5.1 The coating surface to be tested should be carefully cleaned and degreased with appropriate organic solvents such as gasoline, carbon tetrachloride, benzene, etc. The selected cleaning solvent should not change the original state of the coating. 5.2 Cut a test paper slightly larger than the test surface and immerse it in the heated sodium chloride gel solution. When the test paper is completely wet, take out the test paper and drip off the excess solution.
Approved by the Ministry of Machinery Industry on October 25, 1994
Implementation on October 1, 1995
JB/T7509-94
5.3 Place the wet test paper close to the test surface. There should be no bubbles between the test paper and the coating surface. If the test paper becomes dry during the test, sodium fluoride solution should be added appropriately to keep the test paper and the test surface moist. 5.4 After ten minutes, remove the test paper from the test surface and immediately immerse it in potassium ferrocyanide solution. Blue spots will appear on the test paper where there are pores relative to the coating. Take out the test paper and dry it. 5.5 Visually count the number of spots on the test paper. 5.6 If it is necessary to repeat this test in the same area, the test surface should be carefully cleaned with hot distilled water to remove the reaction products remaining on the test coating surface from the previous test. The cleaned sample should be fully dried before proceeding. 6 Test results
The porosity is expressed as the average number of pores per unit area in the test area, in units of: pieces/cm2. If the user requires, the area of ​​the largest single pore spot in the test area should also be measured, in units of: mm; mark the location with the highest pore density in the test area and its porosity, in units of: pieces/cm2.
7 Test report
The test report shall include the following contents:
This standard number;
The location of the test area;
Related coating or product standards;
Test results.
Additional remarks:
This standard was proposed and managed by the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Wuhan Materials Protection Research Institute. The main drafters of this standard were Wang Hongsheng and Xiong Zhongshu.
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