1、 FORD LABORATORY TEST METHOD BQ 103-08 Date Action Revisions 2000 11 10 Revised Edi torial no technical change A. Cockman 1990 05 18 Printed copies are uncontrolled Page 1 of 4 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF ACTIVE CORROSION SITES Application This procedure is used t
2、o determine the density of active corrosion sites on micro - porous electroplated deposits following exposure to copper - accelerated acetic acid - salt spray testing. Apparatus Required Salt Spray Cabinet Refer to ASTM B 117, Appendix “Construction of Apparatus“ Fog Collectors Fog collectors for me
3、asuring the collection rate shall be glass or plastic funnels with the stems inserted into plastic or glass graduated cylinders or flas ks. The funnels shall have a diameter of 100 mm which will provide an area of about 8000 mm. If funnels slightly smaller or larger are used, the area must be determ
4、ined and collection rates calculated for 8000 mm. pH Meter Standard meter. Metallurgical Microscope A metallurgical microscope to be used in determining either crack density or pore density. (A Bausch and Lomb monocular body, Model DM, Bausch and Lomb Number 31 - 20 - 66 - 37 is satisfactory). For d
5、etermining crack density a cross line disc Ba usch and Lomb Number 31 - 16 - 30 or equivalent is required. For determining pore density, a Howard Disc Bausch and Lomb Number 31 - 16 - 15 or equivalent is required. The metric scale is 25 mm long with 1.0, 0.1 and 0.02 mm divisions. Materials Required
6、 Distilled or Deionized Water 10 ppm max total dissolved solids (ASTM D 1888). Sodium Chloride NaCl; ACS reagent grade. FORD LABORATORY TEST METHOD BQ 103-08 Page 2 of 4 Copyright 2000, Ford Global Technologies, Inc. Cupric Chloride CuCl2 2H2O ACS reagent grade. Glacial Acetic Acid ACS reagent grade
7、. Magnesium Oxide Powder; ACS reagent grade. Pumice or Extra Fine Tripoli 250 mesh or finer. Soft Cloth Soft Paper Towels Preparation of Test Solution Refer to ASTM B 368 - “Test Solution“ Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a contr
8、olled atmosphere of 23 +/ - 2 C and 50 +/ - 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure 1. Preparation of test specimens - refer to ASTM B 368 - “Preparation of Test Specimens“. Flat stock should be cut in a
9、pproximately 100 x 200 mm sizes. Samples for test should be collected and handled with extreme care to prevent mechanical scratches and digs on surfaces. The use of racks with slots for separation of samples or wrapping individual samples in soft paper is recommended. If any handling marks are obvio
10、us, these should be noted. 2. Positioning of specimens during test - Refer to ASTM B 368 - “Positioning of Specimens During Test“. 3. Conditions in the salt spr ay cabinet including air supply - Refer to ASTM B 368 - “Air Supply“ and “Conditions in the Salt Spray Chamber“. 4. Period of exposure to c
11、opper - accelerated acetic acid - salt spray testing 22 h (generally 1 cycle of CASS testing per the applicable Enginee ring Material Specification or engineering print). FORD LABORATORY TEST METHOD BQ 103-08 Page 3 of 4 Copyright 2000, Ford Global Technologies, Inc. 5. Cleaning of tested specimens
12、- Refer to ASTM B 368 - “Cleaning of Tested Specimens“. Note: The air supply must be free of oil and other contamination. If the part contains corrosion product staining , it may be washed with a very mild sponge in warm water, but the part should not be subjected to any abrasive cleaning. 6. Evalua
13、te as follows: The corroding (“active“) pore sites are typically larger than the uncorroded sites and have a darker and roug her texture. The density of these active pore sites may be determined as follows: A. GRID METHOD - VISUAL, USING A METALLURGICAL MICROSCOPE 1. In a suitable 10 X microscope ey
14、epiece, insert a micrometer disc (Howard Micrometer Disc, B & L #31 - 16 - 15) contai ning ruled grid squares. The eyepiece should be capable of accommodating the disc in the proper focal plane so that the grid and the image of the plated surface are clear and sharp. 2. Using a standard metallurgica
15、l microscope with the above prepared eye piece and a 10 X objective, to give a total magnification of approximately 100 X, calibrate the ruled grid on the micrometer disc against a stage micrometer ruled in 0.1 mm and 0.01 mm intervals to determine the area covered by the ruled grid. 3. Determin e t
16、he disc magnification factor by taking the reciprocal of the above calculated area. 4. Count the number of active corrosion sites in the area covered by the ruled grid on the micrometer disc. 5. The calculated number of active corrosion sites per squa re centimeter is the product of the number of ac
17、tive corrosion sites counted in the area covered by the ruled grid on the micrometre disc and the micrometre disc magnification factor determined in step 3 above. B. Photomicrographic method using a metallurgical microscope 1. To a standard metallurgical microscope containing a 10 X objective, attac
18、h suitable photomicrographic equipment containing an eyepiece, the combination of which will result in a magnification of about 100 X at the film plane and a film area of at least 65 x 90 mm. Because of variations in such types of photomicrogrpahic equipment, it should be calibrated against a stage
19、micrometer. 2. Photograph the desired representative areas and obtain positive prints showing the active corrosion s ites. FORD LABORATORY TEST METHOD BQ 103-08 Page 4 of 4 Copyright 2000, Ford Global Technologies, Inc. 3. Determine the area of the print. e.g. 65 x 90 mm print = 5850 mm = 58.5 cm 4.
20、 Count the number of active corrosion sites in the entire photographic print. 5. Calculate the actual number of active corrosion sites per square centimeter on th e surface examined by multiplying the number of active corrosion sites on the photographic print by the square of the actual magnificatio
21、n value of the print and divide by the area of the print (determined in para 3). C. PHOTOMICROGRAPHIC METHOD USING INVERTED MICROSCOPIC EQUIPMENT SUCH AS A METALLOGRAPH 1. Place the part or panel on the instrument stage, supported in such a way that the areas to be photographed do not touch or rest
22、on the stage. 2. Using a 10 X objective and a low power eyepiece, such a s 5 X, adjust the bellows on the camera to give a magnification of 100 X at the film plane as determined by calibration against a stage micrometer. 3. Photograph, count, and calculate the number of active corrosion sites per cm
23、 in the same way as in Meth od B above. Record Maintenance 1. Report and maintain records as per ASTM B 368 - “Records and Reports“ Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determinin g proper use and handling in its facilities.
