1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards METHOD OF POROSITY EVALUATION FOR PHOSPHATED AND METALLIC COATING EDS-T-7135 ISSUED DATE: 1990. 10. 15 REVISED DATE: 2006. 06. 19 VERSION: 2 EDS-T-7135METHOD OF POROSITY EVALUATION FOR PHOSPHATED AND METALLIC COATING
2、PAGE: 1/4 ISSUED DATE: 1990. 10. 15 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology 1. PURPOSE The purpose of this standard is to determine and evaluate the porosity of phosphate coating and metallic coatings (Pb, Sn etc) on the metal of ferrous substrates. 2. SCOPE This standard s
3、pecifies the porosity of phosphate coating and metallic coatings (Pb, Sn etc) on the metal of ferrous substrates. This can be applied to post conditioning on phosphate coating with organic materials such as oil, wax or paint. 3. DEFINITIONS 3.1. Phosphate coating : The method of surface treatment wh
4、ich is formed metallic phosphate coating Zn(H2PO4)2, Mn(H2PO4)2etc. by the phosphate substrates on ferrous substrates for promotion to protect the corrosion of metallic products. 3.2. Metallic coating : To be coating the surface of products with the metals such as Pb, Sn etc. 4. METHOD OBTAINING TES
5、T PIECE 4.1. The test piece wherever possible shall be the finished part. 4.2. When procedure 4.1 is impractical, tests shall be conducted on specially prepared test panels. The test panels shall have a surface area of not less than 100 cm2and shall be made from sheet steel to SCP1, KS D 3512. 4.3.
6、Number of test piece : For initial sample approval and arbitration purposes, at least three test pieces and for routine quality control, at least one test pieces shall be tested. 5. TEST PIECE PREPARATION 5.1. Phosphated surface without post treatment shall be tested as received and post treatment b
7、y organic solvent on coating surface shall be degressed in suitable way. 5.2. Metallic coated surfaces shall be initially degressed prior to testing using a suitable solvent (Xylene, Petroleumether). 6. APPARATUS BEFORE TEST 6.1. Suitable apparatus for preparing the test solution 6.2. Filter paper (
8、 Whatman No 42 ) EDS-T-7135METHOD OF POROSITY EVALUATION FOR PHOSPHATED AND METALLIC COATING PAGE: 2/4 ISSUED DATE: 1990. 10. 15 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology 6.3. Suitable swabbing material 6.4. Forceps 7. METHOD OF MAKING THE TEST MEDIUM 7.1. Manufacture of test
9、 medium Test medium shall be made in following components Potassium ferricyanide ( K3 Fe (CN)6 : 10 g Sodium chloride ( NaCl ) : 30 g Wetting agent : 1 g Water or Ionised water : 1 N 7.2. Storage of test medium The test medium shall be stored in a sealed brown glass bottle for 4 months max. The test
10、 medium used for the preparation of the filter paper must not be returned to the bottle. 8. PROCEDURE 8.1. The suitable filter paper shall be dipped into the test medium. 8.2. The filter paper wetted with the test medium shall be placed on the clean surface of the test area, care being taken to avoi
11、d entrapped air bubbles. 8.3. The filter paper shall be in intimate contact with the test piece surface for 1 minute only. 8.4. The porosity of the test filter shall be evaluated in th way of clause 9. and 10. 9. EVALUATION FOR PHOSPHATE COATINGS 9.1. Test filter which test finishes shall be evaluat
12、ed for the porosity of phosphate coatings in compare with added drawings. 9.2. Description for drawings 9.2.1. Grade 1 : A blue tint is permissible but no deep blue spots must occur. 9.2.2. Grade 2 : A blue tint with slightly blue patch formation is permisible but no deep blue spots must occur. 9.2.
13、3. Grade 3 : A blue tint is permissible with deep blue spots. 9.2.4. Grade 4 : A deep blue tint is permissible with deep blue spots. EDS-T-7135METHOD OF POROSITY EVALUATION FOR PHOSPHATED AND METALLIC COATING PAGE: 3/4 ISSUED DATE: 1990. 10. 15 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto &
14、Technology 10. EVALUATION FOR METALLIC COATINGS The porosity shall be evaluated by means of the number of deep blue spots in the test area.( The number is expressed on drawings or material specs.) 11. REFERENCE GME 60209 Determination of Porosity of Coatings on Ferrous Materials EDS-T-7135METHOD OF POROSITY EVALUATION FOR PHOSPHATED AND METALLIC COATING PAGE: 4/4 ISSUED DATE: 1990. 10. 15 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology (Appendix) GRADE 4 UNSATISFACTORY GRADE 3 POOR GRADE 2 GOOD GRADE 1 VERY GOOD
