1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards ZINC - PHOSPHATED COATING WEIGHT MEASUMENT METHOD EDS-T-7936 ISSUED DATE: 1998. 05. 30 REVISED DATE: 2005. 08. 18 VERSION: 2 EDS-T-7936ZINC - PHOSPHATED COATING WEIGHT MEASUREMENT METHOD PAGE: 1/2 ISSUED DATE: 1998. 0
2、5. 30 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology 1. PURPOSE This standard aims at measuring weight of coating formed on the test piece after it passes the pre-treatment chemical process of the paint shop. 2. SCOPE This standard applies to CRS steel that is coated at the pre-tr
3、eatment chemical process of the paint shop. 3. TEST APPARATUS 3.1. Coated test piece- test piece that has passed the pre-treatment chemical process 3.2. Test apparatus 3.2.1. Solution reagent 3.2.2. Drying oven 3.2.3. Thermometer 3.2.4. Scale (capable of measuring down to 1/10,000g) 3.2.5. Hot plate
4、 or a thermostat 3.2.6. Acetone 3.2.7. Vernier calipers 3.2.8. Desiccator 3.2.9. Scissors 4. TEST PIECE CONDITION AND PREPARATION 4.1. Test piece preparation The test piece is prepared by passing the bare CRS piece through the pre-treatment line of the paint shop. It shall be constructed to more tha
5、n meet requirements for each process. 4.2. Solution reagent preparation 4.2.1. Production of CRS coating weight solution reagent Put 50g of Chromium( )Oxide(CrO3) into a 1000L beaker, and fill it with pure water to reach 1000L , and stir it until it is completely melted on the hot plate. 4.2.2. Prod
6、uction of aluminum or zinc coating weight solution reagent Put 276L 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. EDS-T-7936ZINC - PHOSPHATED COATING WEIGHT MEASUR
7、EMENT METHOD PAGE: 2/2 ISSUED DATE: 1998. 05. 30 REVISED DATE: 2005. 08. 18 VERSION: 2 GM DAEWOO Auto & Technology 5. TEST PROCEDURES 5.1. CRS coating weight test method 5.1.1. Place the pre-treated test piece into and oven to dry at 1355min. 5.1.2. Put the dried test piece into the desiccator to co
8、ol to ambient temperature. 5.1.3. Cut the test piece to 10050mm with scissors. 5.1.4. Weigh the test piece down to 1/10,000g.-W1 5.1.5. Heat the solution reagent of clause 4.2.1 to 70 and keep that temperature. After that, melt a film by digesting the test piece for 15 minutes. - In case of CRS 5.1.
9、6. Melt a film by digesting the solution reagent of clause 4.2.2 for 5 minutes. - In case of aluminum or zinc 5.1.7. After washing the dissolved test piece with industrial water and subsequently with D.I water, absorb water with towel paper and wash it with acetone. 5.1.8. After drying the washed te
10、st piece inside a dry oven at 1355min, cool inside the desiccator. 5.1.9. Weigh the test piece, which is cooled to ambient temperature, down to 1/10,000g.-W2 5.1.10. Measure precisely the area of the test piece with vernier callipers.-A 6. EVALUATION Coating weight = ( W1 - W2 ) X 106 / A (g/ ) GMDAT requirements shall be 1.5 3.5(g/ ).
