1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards ALKALI SOLUBILITY TEST METHOD OF ZINC COATED PANEL EDS-T-7969 ISSUED DATE: 2000. 05. 28 REVISED DATE: 2005. 08. 18 VERSION: 2 EDS-T-7969ALKALI SOLUBILITY TEST METHOD OF ZINC COATED PANEL PAGE: 1/3 ISSUED DATE: 2000. 0
2、5. 28 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology 1. PURPOSE This standard specifies the method of evaluating solubility of the zinc coat, which is formed in the pre-treatment process, by alkali. 2. SCOPE This standard applies to all kinds of steel used for the vehicle body on
3、which zinc coat is formed and is to evaluate solubility of the zinc coat by alkali when the body surface is alkalified by electrolysis in elecro-deposition painting. 3. DEFINITION OF TERMS 3.1. Alkali solubility: Solubility of the zinc coat in alkali solution 4. TEST EQUIPMENT AND CHEMICALS 4.1. Equ
4、ipment 4.1.1. Fume hood It is used to discharge the toxic gas generated during alkali solubility measurement. 4.1.2. Vernier calipers Instrument to precisely measure the size of the test piece 4.1.3. Desiccator Equipment to store and cool the test piece under the normal temperature 4.1.4. Scale Capa
5、ble of measuring at least down to 1/10,000g 4.1.5. Scissors Use to cut the test piece into a certain size 4.1.6. PH meter Equipment to adjust the PH of the dissolved reagent 4.1.7. Oven Use to dry the test piece 4.1.8. Glass bar Use to mix the dissolved reagent 4.1.9. 2N plastic or glass beaker 4.1.
6、10. Stop watch EDS-T-7969ALKALI SOLUBILITY TEST METHOD OF ZINC COATED PANEL PAGE: 2/3 ISSUED DATE: 2000. 05. 28 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology 4.1.11. Temperature oven 4.1.12. Pincette 4.1.13. Syringe 4.1.14. Protective rig Vinyl gloves, mask, etc 4.2. Chemicals 4.
7、2.1. 0.5% NH4Cl solution 4.2.2. NH4OH 4.2.3. CrO34.2.4. Ethanol 4.2.5. Acetone 5. TEST PROCEDURES 5.1. Test piece build 5.1.1. Build the pre-treated test piece for alkali solubility test of the zinc coat using the production process and lab equipment. 5.1.2. Wet a piece of gauze with ethanol to clea
8、n the pre-treated test piece surface with it and then store it in the desiccator under the normal temperature. 5.1.3. Use scissors to cut the test piece into 50 100 . 5.1.4. Precisely measure the surface area of the test piece with vernier calipers (Both sides) -A 5.1.5. Precisely weigh the test pie
9、ce with a 1/10000g scale.-W1 5.2. Preparation of dissolved reagent 5.2.1. Pour 0.5% NH4Cl solution into the 1N plastic beaker and adjust to pH=10 using NH4OH solution. As the above solution creates highly stimulant toxic gas, this procedure shall be conducted in the fume hood equipped with the toxic
10、 gas discharge system with the protective gloves and mask worn. 5.2.2. Coated steel: Put 276 L of the Ammonium Hydroxide(NH4OH, 29%) solution & 1.0g of Chromium( )Oxide(CrO3) to 1000L beaker and dilute it with water to reach 1000L . Then, stir it until it is completely melted. 5.2.3. General steel(C
11、RS): Put CrO3 into the 1N plastic beaker and dissolve it with pure water to make concentration of 5%. EDS-T-7969ALKALI SOLUBILITY TEST METHOD OF ZINC COATED PANEL PAGE: 3/3 ISSUED DATE: 2000. 05. 28 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology Adjust the beaker volume and amount
12、 of dissolved reagent depending on the test piece size and test purpose. 5.3. Test sequence 5.3.1. Dip the test piece into the solution in clause 5.2.1 for 5 minutes under the normal temperature. As the above solution creates highly stimulant toxic gas, this procedure shall be conducted in the fume
13、hood equipped with the toxic gas discharge system with the protective gloves and mask worn. 5.3.2. After taking the test piece out, clean it with pure water, dry in a clean oven set to 135 for 5 minutes and then cool it inside a desiccator under the normal temperature. 5.3.3. Precisely weigh it with
14、 a scale.-W2 5.3.4. For coated steel (1) Dip the coated steel treated as in clause 5.3.2 in the solution prepared in clause 5.2.2 for 5 minutes under the normal temperature. (2) After taking the test piece out, clean it with pure water, dry in a clean oven set to 135 for 5 minutes and then cool it i
15、nside a desiccator under the normal temperature. (3) Precisely weigh it with a scale.-W3 5.3.5. For general steel (1) Dip the coated steel treated as in clause 5.3.2 in the solution prepared in clause 5.2.3 for 15minutes at 70. (2) After taking the test piece out, clean it with pure water, dry in a
16、clean oven set to 135 for 5 minutes and then cool it inside a desiccator under the normal temperature. (3) Precisely weigh it with a scale.-W3 6. CALCULATION FORMULA 6.1. Coat solubility (g/ ) = ( W1 W2 ) A 1066.2. Coat weight (C/W, g/ ) = (W1 W3) / A 1066.3. Alkali solubility (%) = (Coat solubility
17、 Coat weight) 100 = ( W1 W2 ) / ( W1 W3 ) 100 7. DECISION 7.1. Get the mean of 3 measurements. 7.2. GMDAT specification 7.2.1. For coated steel plate : No specification EDS-T-7969ALKALI SOLUBILITY TEST METHOD OF ZINC COATED PANEL PAGE: 4/3 ISSUED DATE: 2000. 05. 28 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology 7.2.2. For general steel plate : Max. 3%
