Method for detecting quality of phosphate coating
A detection method and phosphating film technology, applied in the direction of electrochemical variables of materials, etc., can solve the problems of complicated operation, long test time, incomplete detection, etc., and achieve the effect of simple analysis of test results, accurate test results, and short test time.
Active Publication Date: 2014-11-05
ANGANG STEEL CO LTD
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Problems solved by technology
[0004] 1. The detection is not comprehensive: the crystallization state of the phosphating film cannot be comprehensively detected, and only the local characteristics of the crystallization state of the phosphating film can be detected;
[0005] 2. Poor detection accuracy: the test conditions are harsh, the test time is long, and the human error is large;
[0006] 3. Data analysis is complex;
[0007] 4. The operation is complex and requires special test equipment;
[0008] 5. The electrolyte is highly corrosive, which can easily cause test errors in the quality of the phosphating film
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Embodiment Construction
[0028] The best embodiment of the present invention will be described below by detecting the quality of the phosphating film of four different phosphating films.
[0029] Step 1. Take four samples a, b, c, and d with different phosphating coatings.
[0030] Step 2, process the above sample into a test piece of 100mm×100mm.
[0031] Step 3, using the M273 constant current / potentiostatic instrument, using a three-electrode electrochemical test system, in a 0.5% potassium dihydrogen phosphate solution by mass percentage, respectively have different phosphating films for a, b, c, and d Test the open circuit potential curve of the test piece. When the open circuit potential curve has an inflection point, the test ends, and the time when the inflection point appears is recorded. The test polarization curve is shown in figure 1 , image 3 , Figure 5 , Figure 7 .
[0032] Step 4. According to the time when the inflection point on the polarization curve measured in step 3 appear...
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The invention discloses a method for detecting the quality of a phosphating film. First, the phosphating sample is processed into a test piece with a surface area not less than 1 cm2, and a three-electrode electrochemical testing system is adopted, wherein the working electrode is a test piece and a reference electrode. The calomel electrode and the auxiliary electrode are platinum wire mesh. The solute concentration of the electrolyte is 0.45% to 0.55% potassium dihydrogen phosphate test solution at room temperature. The relationship between the open circuit potential and time is tested. After the inflection point occurs, record the time at which the inflection point occurs. When the inflection point occurs at t≤300s, the phosphating film quality is poor; when the inflection point occurs at 300s<t≤700s, the phosphating film quality is average; when the inflection point occurs at 700s<t≤1000s, the phosphating film quality is good; When the inflection point appears time t>1000s, the phosphating film quality is very good.
Description
technical field [0001] The invention provides a method for detecting the quality of a phosphating film, in particular an electrochemical test method for detecting the crystallization state of the phosphating film. Background technique [0002] As an important surface pretreatment technology, phosphating has been widely developed and applied in corrosion resistance, coating, lubrication and finishing. The crystallization state of the phosphating film includes the crystal size of the phosphating film grains, the uniformity of the phosphating film and the compactness of the phosphating film. The comprehensive effect of these three aspects will directly reflect the quality of the phosphating film and directly affect its quality. Therefore, it is particularly important to detect the crystallization state of the phosphating film. At present, the methods for detecting phosphating film include: film weight method, copper sulfate pitting test, salt water test, electrochemical impeda...
Claims
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IPC IPC(8): G01N27/26
Inventor 陈义庆徐小连丁燕勇钟彬肖宇徐承明王永
Owner ANGANG STEEL CO LTD