GMKOREA EDS-T-7136-2006 METHOD OF PLATING THICKNESS MEASUREMENT.pdf

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1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards METHOD OF PLATING THICKNESS MEASUREMENT EDS-T-7136 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 1/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 20

2、06. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 1. PURPOSE This standard aims at obtaining an accurate and objective test results by standardized test method. 2. SCOPE This standard specifies the thickness measurement method of plating effective surfaceNote1) (hereinafter referred to as the “plati

3、ng“) of plated products for automobile parts(hereinafter referred to as the “products“). Note 1)The effective surface means a portion that is used as a product. 3. TYPE OF TEST METHOD Test methods shall be 4 types as follows. Test method Measuring range Applicable materials Microscopic cross-section

4、 test method 2 25W General metals, Anodic plating on aluminum base Electrolytic test method Chromium: 0.15mm max. Others: 1.5W min. General metals Plating weight test method by mass measurement - General metals, Anodic plating on aluminum base Magnetic type test Within 10% of the actual value exclud

5、ing thin plating with the accuracy of 5W or less . General metals . Magnetic coating on non-metallic base4. TEST SAMPLE 4.1. Test samples shall be taken from the effective surface of the product. However, when it is impossible, alternative test pieceNote2)may be used. 4.2. Foreign substances such as

6、 dusts and oil on the sample shall be removed before measurement to prevent damage on the coating. Note 2)Test pieces shall represent the product, and the base and coating condition of test pieces shall be the same as those of the product. 4.3. For initial sample approval purposes, at least 3 test p

7、ieces shall be tested and for routine quality control, at least 1 test piece shall be tested. 5. TEST METHOD 5.1. Microscopic cross-section test method 5.1.1. General It is a method of measuring film thickness by observing the cross-section of the test piece film under a microscope. EDS-T-7136METHOD

8、 OF PLATING THICKNESS MEASUREMENT PAGE: 2/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 5.1.2. Device A microscope device with the ocular scale or the one specified in KS B 5601Micrometer Microscope shall be used. 5.1.3. Test piece (1) Sampling place:

9、Test piece shall be sampled from the effective surface of the product. When it is impossible, alternative test piece may be used.Note1)In this case, the test piece shall be the one that represents the product, and the base materialNote1) and coating conditionNote2)of the test piece shall be the same

10、 as those of the product. (2) Shape: For test piece, a portion of 5 30mm in length shall be sampled from the effective surface. (3) Treatment prior to measurement: The test piece shall be cleaned with soft cloth soaked with appropriate solventNote3) according to level of contamination prior to measu

11、rement. * Note 1)Composition, manufacturing conditions(by kind and quality of material) and pre-treatment surface condition of the base material shall be, in principle, the same as those of the product. 2)The same treatment solution and processing condition as that of the product, shall be applied o

12、n the test piece to reflect the effects of work condition such as pre-treatment and plating. 3)For the solvent, aceton, ethyl alcohol, ethyl ether, methyl ether, etc. shall be used, but the one which corrodes the test piece and forms protection film on the test piece shall not be used. 5.1.4. Test M

13、ount the test piece which was polished beforehand or bury it vertically into resin or alloy with low melting point. Polish it vertically, while taking care not to damage the surface of the film. Measure at 3 points or more on the parallel portion of the section after magnifying it to an appropriate

14、size with a micrometer microscope or projecter.Note4)The minimum value among them shall be the film thickness. * Note 4)The scale of microscope projector shall be corrected by a standard ruler. 5.1.5. Factors affecting precision of measurement (1) Surface roughness (2) Inclination of the section (3)

15、 Deformation of the film (4) Formation of round (5) Microscope magnification 5.2. Electrolytic test method 5.2.1. General It is a method of measuring the plating thickness by applying the fact that the plating time is proportional to the time to remove the plating of a specified small area anodicall

16、y using constant current electrolysis. 5.2.2. Device It is composed of an electrolytic bath generating constant current and its accessories. Sufficient calibration of the EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 3/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DA

17、EWOO Auto & Technology device shall be performed in advance. The following item shall be noted in the calibration. (1) The device shall be calibrated according to its characteristics using standard thickness before using. Though measuring is in progress, a leveling to an appropriate interval is nece

18、ssary. (2) For the standard sample used for calibration, the coated one in uniform and known thickness and with the same kind shall be used. (3) In calibration, the material shall be the same as or similar to the base or coating of the measured sample as the material property of the base and plating

19、 influence the measuring accuracy. 5.2.3. Test piece The test piece shall be an effective surface of the product. 5.2.4. Test (1) Operation shall conform to the handing method of each device. (2) The composition of the base, plating and electrolytic solution Note3) shall be examined whether it meets

20、 Tables 1 and 2. (3) If the base is exposed due to melting of the plating, the electric potential (or voltage) changes abruptly. This moment is the end of the test and the time required for it or integrated electric energy shall be recorded as necessary. (4) When the plating of the portion surrounde

21、d with gasket is melted and removed completely, operation shall be finished. (5) The plating thickness shall be obtained according to indication of the device. * Note 3)The electrolytic solution, which is not damaging to plating in case the electrolysis is not applied and whose anodic current effici

22、ency is 100% and the voltage change at end of the test is remarkable in case the electrolysis is applied, shall be used. 5.2.5. Factors influencing measuring accuracy (1) Composition of the electrolytic solution (2) Electric current (3) Testing area (4) Agitation (5) Alloying between plating and bas

23、e (6) Cleanliness of testing area (7) Density of plating (8) Purity of plating EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 4/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology Table 1. Application of Electrolytic Solution Base Plating Fe Cu and

24、Cu alloy(Brass, etc.)Ni Al Zn Cd No. 1 No. 1 - - - Cr No. 2 No. 3 No. 2 or No. 4 No. 2 or No. 4 - Cu No. 5 - No. 6 No. 5 or No. 6 No. 7 Pb No. 8 No. 8 No. 8 - - Ni No. 9 No. 10 - No. 9 - Ag - No. 11 No. 11 - - Sn No. 12 No. 12 No. 12 No. 13 - Zn No. 14 No. 14 - - - Remark) The number in Table 1 indi

25、cates the number of ectrolytic solution in Table 2. Table 2. Example of Electrolytic Solution No. Composition of electrolytic solution Remark 1 Make 1000ml of electrolytic liquid by dissolving 30g of potassium chloride and 30g of ammonium chloride into pure water. - 2 Dilute 95ml of lynn acid with a

26、 specific gravity of 1.75 with 1000ml of pure water and add 25g of absolute chromic acid to this solution. This is used in plating of 5W min. and for current density, about 100mA/cm2would be adequate. At this time, error shall be within 10%. 3 Make 1000ml of electrolytic liquid by dissolving 100g of

27、 sodium carbonate into pure water. This is used in plating of 5W min. and for current density, about 100mA/cm2would be adequate. 4 Dilute 64ml of lynn acid with a specific gravity of 1.75 with pure water. This is suitable for Cr plating for thin decoration. For current density, about 100mA/cm2would

28、be adequate. 5 Make 1000ml of electrolytic liquid by dissolving 800g of ammonium nitrate into pure water and then add 10ml of ammonium hydroxide with a specific gravity of 0.88. For true value of thickness, low value of 12% shall be indicated. 6 Make 1000ml of electrolytic liquid by dissolving 100g

29、potassium sulfate into pure water and then add 20ml of lynn acid with a specific gravity of 1.75 to this. - 7 Contents percent of silicon fluoric acid in the solution shall be 30%(v/v) min. If magnasium silicon fluorine is added to this solution, this solution shows weak acid reaction. 8 Make 1000ml

30、 of electrolytic liquid by dissolving 200g sodium acetate and 200g of ammonium acetate with pure water. For true value of thickness, high value of within 5% shall be indicated. EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 5/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3

31、 GM DAEWOO Auto & Technology No. Composition of electrolytic solution Remark 9 Make 1000ml of electrolytic liquid by dissolving sodium nitrate of 800g into pure water and then add 50ml of giourea of 67g/N to this. After the lapse of 5 days, this solution is feared to deteriorate and so it shall not

32、be used then. 10 Dilute 100ml of hydrochloric acid with a specific gravity of 1.18 with 1000ml of pure water. For current density, about 400mA/cm2 0.4A/dm2 would be adequate. 11 Make 1000ml of electrolytic liquid by dissolving kalrium fluorine of 100g into 1000ml of pure water. This shall not be app

33、lied to the plating including Sb or Bi. 12 Dilute 170ml of hydrochloric acid with a specific gravity of 1.18 with 1000ml of pure water. - 13 Make 1000ml of whole liquid amount by injecting carefully 50ml of sulfuric acid with a specific gravity of 1.84 into pure water. - 14 Make 1000ml of electrolyt

34、ic liquid by dissolving 100g of kalrium chloride into pure water. - Remark) Reagent used in the electrolytic liquids of the table shall be grade 1 min. 5.3. Magnetic type test 5.3.1. General It is a method of measuring thickness by measuring magnetic attraction force between magnet whose force varie

35、s according to the thickness of non-magnetic coating on the surface of magnetic base metal and base metal or magnetic resistance of magnetic flux passing through coating and base metal. (The base metal which is this method does not apply to already magnetized.) 5.3.2. Device For the use of device, s

36、ufficient calibration shall be done to the device, as for calibration, attention shall be paid to the following. (1) Calibrate the device according to the characteristics of the device with the standard sample of appropriate thickness prior to its use and also during measurement, calibration needs t

37、o be done at adequate intervals. (2) The standard sample used in calibration shall be the one which has uniform thickness, is thin foil of already known thickness or is coated with plating. (3) The material quality of the base and plating for calibration standard sample shall be the same as or simil

38、ar to those of sample to be measured because the material quality of base and plating affects the precision of measurement at the time of calibration. 5.3.3. Test piece Measuring location shall be the effective surface. 5.3.4. Test (1) Operation shall be done according to orders of the handling meth

39、od of each equipment. EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 6/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology (2) Measurement shall be done at the same point where the calibration is performed and the measuring ruler shall be placed in

40、a certain direction and pressure. (3) Measurement shall be usually be conducted at least three times at the same location and its value shall be the mean value of 3 measurements excluding abnormal values. 5.3.5. Factors which influence the precision of measurement (1) Thickness of plating (2) Magnet

41、ic characteristics of base metal (3) Thickness and shape of base metal (4) Surface roughness (5) Edge effect (6) Curve rate of surface (7) Magnetic flow (8) Foreign substances (9) Conduction rate of plating (10) Probe pressure 5.4. Plating weight test method by mass measurement 5.4.1. General It is

42、a method of obtaining approximate thickness(W ) of the surface film of the test piece by measuring the mass of the film whose density is already known. 5.4.2. Device (1) Chemical scale beam: The range of measured weight shall be within 200g and the precision of measurement shall be within 0.001g. (2

43、) Device for measuring area: A device for dimension measuring, whose precision is within 1/100 of measuring length or 0.1mm or an device which is capable of measuring the area directly and whose precision is within 0.1mm2. 5.4.3. Test piece (1) Sampling location: The same as (1) of 5.1.3. (2) Size:

44、Standard dimension shall be 50100mm. (3) Pretreatment: The same as (3) of 5.1.3. EDS-T-7136METHOD OF PLATING THICKNESS MEASUREMENT PAGE: 7/7 ISSUED DATE: 1988. 07. 15 REVISED DATE: 2006. 06. 19 VERSION: 3 GM DAEWOO Auto & Technology 5.4.4. Peeling-off solution Kind Peeling-off solution Cu, Brass, Si

45、lver on steel base Ammonium hydroxide (28%) - 50 W/O Hydrogen peroxide (3%) - 50 W/O Cd, Zn on steel base Ammonium nitrate(saturated solution) Ni on steel base Nitric acid - 30ml HCl - 3 solution Zn or Zn alloy on steel base (HCl : H2O = 1 : 3) solution + Hexamethylen tetraamine 30% solution 3-4 dro

46、ps 5.4.5. Thickness conversion method T = W/K A T : Plating thickness(W ) W : Calculated plating weight A : Test area K : Constant K value of each metal shall be as follows. Cd : 142 Cu : 146 Zn : 117 Ni : 146 Tin : 119 Ag : 172 Cr : 116 Pb : 186 5.4.6. Test (1) Measure the area of plated surface of

47、 the sample of suitable weight and dimension correctly with a dimension measuring device whose precision is within 1/100 of the length measured or 0.1mm or an area meter whose precision is within 0.1mm. (2) After cleaning the test piece in order to remove a contaminant on plating surface, conduct me

48、asurement accurately with chemical scale beam. (3) Peel off plating completely by dipping the sample into peeling-off solution or performing electrolysis of the sample in the solution. (4) Make the amount subtracted from the previous weight the plating weight by measuring the sample which is fully d

49、ried. (5) Obtain attached plating amount per unit area by dividing plating weight by previously measured area and then mark it with g/m2. (6) Turn the weight per unit area into plating thickness. 6. RULES FOR ROUNDING OFF NUMERICAL VALUES FOR PLATING THICKNESS. (N0TE 1) 6.1. Ni, Zn, Cu, DACRO, Sn shall be rounded off to integral number. 6.2. Cr and Cu shall be recorded up to second decimal place below point. Note 1) Rules for rounded off numerical values : KS A 0021.