1、 FORD LABORATORY TEST METHOD BQ 105-01 Date Action Revisions 2000 11 10 Revised Editorial no technical change A. Cockman 1990 05 18 Printed copies are uncontrolled Page 1 of 4 Copyrigh t 2000, Ford Global Technologies, Inc. COPPER-ACCELERATED ACETIC ACID-SALT SPRAY TESTING (CASS TEST) Application Th
2、is procedure is used to determine the corrosion resistance primarily of stainless steel and plated parts. With respect to plated parts, it is used primarily for copper/nickel/c hromium and nickel/chromium electroplated parts. Apparatus Required Cabinet Refer to ASTM B 117, Appendix m “Construction o
3、f Apparatus“. The test chamber shall be at least 0.5 m capacity and preferably larger to permit adequate control of the environ ment. The test chamber shall be large enough to test full size (uncut) parts. Fog Collectors Fog collectors for measuring the collection rate shall be glass or plastic funn
4、els with the stems inserted into plastic or glass graduated cylinders or flasks. The funnels shall have a diameter of 100 mm which will provide an area of about 8000 mm 2 . If funnels slightly smaller or larger are used, the area must be determined and collection rates calculated for 8000 mm. pH Met
5、er Standard meter. Evaluation Grid A transparent grid of pliable plastic, marked off in 6.4 mm squares, is used to determine the amount of corrosion on the test specimens. The standard grid shall be rectangular shape and shall contain one hundred 6.4 mm squares (the lines marking the squar es shall
6、not exceed 0.13 mm in width). The percent corrosion is determined by placing the grid in firm contact with the (plated) surface of the test specimen and counting the grid units containing corrosion defects. Refer to Figure 1. A convenient grid size for overall evaluation is 64 x 64 mm. Illumination
7、for Evaluating Test Results Fluorescent daylight white 645 - 860 lux at area where examination of part is being performed. FORD LABORATORY TEST METHOD BQ 105-01 Page 2 of 4 Copyright 2000, Ford Global Technologies , Inc. Material Required Distilled or Deionized Water 20 micromhos/cm at 25 C maximum
8、conductivity (ASTM D 1125). Sodium Chloride NaCl; reagent grade. Cupric Chloride CuCl 2 C 2H 2 O reagent grade. Glacial Acetic Acid Reagent grade. Magnesium Oxide Powder; reagent grade. Pumice or Extra Fine Tripoli 250 mesh or finer. Soft Cloth Soft Paper Towels Preparation of Test Solution Refer to
9、 ASTM B 368 - “Test Solution“ Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/ - 2 C and 50 +/ - 5 % relati ve humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise
10、 specified. Procedure 1. Preparation of test specimens - refer to ASTM B 368 - “Preparation of Test Specimens“. Flat stock should be cut in approxi mately 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
11、use of racks with slots for separation of samples or wrapping individual samples in soft paper is reco mmended. If any handling marks are obvious, these should be noted. FORD LABORATORY TEST METHOD BQ 105-01 Page 3 of 4 Copyright 2000, Ford Global Technologies , Inc. 2. Positioning of specimens duri
12、ng test - Refer to ASTM B 368 - “Positioning of Specimens During Test“. 3. Conditions in the salt spray cabinet including air supply - Refer to ASTM B 36 8 - “Air Supply“ and “Conditions in the Salt Spray Chamber“. Determination of the corrosion effect of the CASS test using the nickel panels shall
13、be on - going. 4. Period of test - the time and number of cycles shall be specified by the applicable Engineer ing Material Specification or Engineering print. 5. Cleaning of tested specimens - Refer to ASTM B 368 - “Cleaning of Tested Specimens“. Note: The air supply must be free of oil and other c
14、ontamination. 6. Evaluate as follows: Hold the part approxim ately 300 mm from the eye in a room lighted with daylight white fluorescent light and examine for the following concerns: red rust, stain discoloration, etching, blisters, pits, green corrosion, white corrosion, and cracks. The part should
15、 be set against a white background with 645 -860 lux illumination in the area where examination is being performed. 6A. Report “overall corrosion“ as follows: Lay the transparent grid containing 6.4 mm squares over the test specimen and count the squares containing one o r more defects. Do this for
16、the entire significant surface. Note: Fine blisters, etc., may be seen through the grid only if it is in close contact with the surface of the test specimen. Finger - prints and light soil may be removed from the grid by was hing with mild soap and wiping dry with a soft paper towel. Divide the numb
17、er of 6.4 mm squares containing defects by the total number of squares covering the significant surface of the part. This figure x 100 = percent overall corrosion. Example: If the part has 1650 6.4 mm squares and the number of squares containing one or more defects was 70 then 70 x 100 = 4.2 % overa
18、ll corrosion 1650 FORD LABORATORY TEST METHOD BQ 105-01 Page 4 of 4 Copyright 2000, Ford Global Technologies , Inc. Figure 1 6B. Report localized corrosion as follows: Lay the 64 x 64 mm transparent grid (100 6.4 mm squ ares) over the test specimen where the greatest number of defects are found. Cou
19、nt the squares containing one or more defects. Squares containing corrosion spots x 100 = % localized corrosion 100 7. Report as per ASTM B 368 - “Records and Reports“. On die cast parts, the white corrosion products may be larger than the actual blister or hole (i.e. pit) in the plate. Only the dia
20、meter of the defect is measured when determining conformance to the maximum defect size requirement specified in the applic able Engineering Material Specification. If in doubt as to the actual size of the corrosion spot, clean the part with light rubbing, using tripoli polishing power or similar mild abrasive and again examine. Chemicals, materials, parts, and equipment ref erenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.
