1、 FORD LABORATORY TEST METHOD BQ 007-01 Date Action Revisions 2000 11 09 Editorial no technical change A. Cockman 1992 08 04 Printed copies are uncontrolled Page 1 of 6 Copyright 2000, Ford Global Technologies, Inc. FORD ANODIZED ALUMINUM CORROSION TEST ( F.A.C.T. ) Application This procedure describ
2、es an accelerated test for determining the resistance to corrosion of anodized aluminum parts. Scope The procedure determines the corrosion resistance of an anodic c oating by indirectly measuring its electrical resistance while it is being attacked electrolytically. The cumulative (integral) D.C. v
3、oltage drop across a test specimen during a specified period of time is used as the measure which establishes a FACT valu e for the coating. Apparatus and Solutions Required F.A.C.T. Instrument The apparatus required for F.A.C.T. testing consists of a cell assembly with a corrosion resistant anode,
4、an electrolyte holder with a gasket which seals to the surface being tested , a suitable electrolyte, a clamp with a pointed screw to contact the basis aluminum, a source of D.C. power, a series resistance to cause the voltage across the cell to be dependent on the cell resistance, and a means for i
5、ntegrating the voltage across th e cell during a predetermined test period. The apparatus which has successfully produced the conditions required by this method is shown schematically in Figure 1. Source: Electronic Applications Specialists, Inc. 1250 Holden Milford, MI 48042 (313) 685 - 8283 The fo
6、llowing are the circuit parameters: 1. Output voltage of power source = 46 V +/ - 1 %. Regulation: line and load +/ - 0.05 %. 2. Series resistance, R1 = 54 kilohms (nominal value, adjusted so that with R3 in circuit, voltage across R2 + R3 = 4.16 V). 3. Calibration resistance, R3 = 5 kilohms +/ - 0.
7、25 %. Scale adjust resistance, R2 = 560 ohms +/ - 1 %. 4. Potential across calibration resistance, R3 = 3.74 V. FORD LABORATORY TEST METHOD BQ 007-01 Page 2 of 6 Copyright 2000, Ford Global Technologies, Inc. 5. Potential across R2 + R3 = 4.16 V. (This voltage integrated for 180 seconds = 749 volt -
8、seconds.) 6. Test period = 180 s +/ - 0.2 %. 7. Integrator: Input resistance = 10 megohms. Accuracy (with 5 kilohms calibration resistance and180 s test period). 749 volt - seconds +/ - 1 %. 8. Resistance, R4 = 156 kilohms +/ - 1 %. 9. Milliameter: 0 - 1mA D.C. 10. Glass tube: 9 mm O.D., 6.3 mm I.D.
9、, 76 mm. 11. Rubber gasket with a 3.17 mm hole. Kocour gasket “A.“ Source: Kocour 4800 S. St. Louis Avenue Chicago, IL 60632 12. The anode is a platinum rod, 2.06 mm diameter, 89 mm long. It is held in a Fahnestock clip and 25.4 mm +/ - 20 % of the rod is immersed in the electrolyte. 13. Electrolyte
10、 - CASS solution as described below. Height of electrolyte in glass tube 38 mm +/ - 20 %. Note: Older equipment not meeting these parameters may be used only with the concurrence of Division Chemical and Metallurgical or SQA. pH Meter Curtin Matheson Catalog No. 138 - 4040 or equivalent. Electrolyte
11、 The CASS electrolyte used in the probe is made up as follows: Distilled water - 5 ppm max total dissolved solids. Sodium Chloride - NaCl reagent grade. Cupric Chloride CuCl2 2H2O reagent grade. Acetic Acid - glacial reagent grade. Weigh 200 g of sodium chloride and 1.0 g of cupric chloride, dissolv
12、e in 3.8 L of distilled water and mix thoroughly . The pH of the solution at this point should be between 5.0 and 6.0. Adjust the pH of the solution to be between 3.0 and 3.2 with acetic acid. It has been determined that variations in the input resistance of pH meters (causing different amounts of c
13、ur rent to be drawn from the pH cell) may affect the pH reading of poorly poised solutions such as the F.A.C.T. electrolyte. The readings for well - buffered solutions (which are not affected by the current drawn) however, will be correct. Consequently, in ad dition to checking the pH meter with sta
14、ndard buffer solutions of pH 2.0 and 4.0, a titration method should be used to check for the correct amount of acetic acid in the electrolyte. FORD LABORATORY TEST METHOD BQ 007-01 Page 3 of 6 Copyright 2000, Ford Global Technologies, Inc. The method consists of titrating 25 mL of electrolyte, to wh
15、ich 3 drops of phenolphthalein have been added, with 1 normal sodium hydroxide to a pink end point. The amount of sodium hydroxide used should never be less than 0.4 mL or more than 1.0 mL. If the solution was made too acid, it should not be brought back to the corr ect pH by adding sodium hydroxide
16、. Consequently, a low pH solution should be discarded and a new one made. Experience has shown that the maximum amount of acetic acid added should not exceed 10 mL/38 L for a properly prepared solution. Accessories Items which are not provided with the F.A.C.T. instrument, but which are useful in co
17、nducting tests are as follows: 1. Support Stand - Large size, such as Fisher Scientific Co. Catalog No. 14 - 670, to support probe. 2. Utility Clamp - To hold probe - Fisher N o. 5 - 766. 3. Eye Dropper - Large size with plastic tubing extension for removal of electrolyte and rinse water from probe.
18、 4. Washing Bottle - Polyethylene - 500 mL, such as Fisher No. 3 - 409 - 10. These are used for filling and rinsing probe. 5. Wooden Blocks - Four 50 x 100 x 200 mm wood blocks, used in positioning of parts. 6. Modeling Clay - Used in positioning of parts. Conditioning and Test Conditions All test v
19、alues indicated herein are based on material conditioned in a controlled atmosphere o f 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 Circuit Calibration After a warm -up period, a chec
20、k of the calibration of the complete elec trical circuit shall be made by substituting the 5000 ohm calibration resistor for the F.A.C.T. cell and running the test for a complete test period. The limits for the F.A.C.T. value obtained are 750 +/ - 7 volt - seconds. If the F.A.C.T. value obtained is
21、out of tolerance, appropriate adjustments or repairs shall be made to the electrical circuit and the calibration check repeated. The calibration check shall be made at least once for each 8 h of operation and the results logged. A check for contaminatio n of the anode and electrolyte shall be made b
22、y running a complete test on clean, unanodized aluminum. FORD LABORATORY TEST METHOD BQ 007-01 Page 4 of 6 Copyright 2000, Ford Global Technologies, Inc. For clean, unanodized, mill finish AA5457 alloy, it is possible to maintain a F.A.C.T. value of 600 +/ - 10 volt - seconds for several days. If th
23、e F.A.C. T. value obtained is out of tolerance, appropriate cleaning of the anode or adjustment of the electrolyte shall be made and the check repeated. Note: The platinum rod used as the anode must be initially flame - cleaned until insertion of the glowing rod in the flame no longer discolors the
24、flame. Subsequent cleaning consists of rinsing the rod with deionized or distilled water and wiping it with a clean tissue after each test. This mechanical wiping impedes the gradual build -up of contaminants. The diame ter of the rod is large enough to permit effective wiping. With care, the princi
25、pal precaution being to avoid touching the rod with ones fingers, the F.A.C.T. values on unanodized aluminum can be kept within the specified limits for several days or weeks depending upon use. Test Specimen The type, age*, and number of test specimens to be used, as well as the criteria for the ev
26、aluation of the test results, shall be defined in the specifications covering the material or product being tested or mutually ag reed upon by the buyer and the seller. *J. Stone, H.A. Tuttle, and H.N. Bogart, “The Ford Anodized Aluminum Corrosion Test - FACT“ Plating, volume 53 1966, pp 877 - 888.
27、Since an anodic coating on aluminum may change characteristics as it ages, the lengt h of time between application of the anodized finish and F.A.C.T. testing should be specified. Depending upon ambient conditions, aging is most rapid immediately following anodizing, but may continue for many weeks.
28、 Test Condition Temperature: The test s hall be conducted in a location where the temperature is 24 +/ - 1 C. Preparation of Test Specimens The surfaces of the specimens shall be suitably cleaned. The cleaning method shall be optional depending on the nature of the surface and the contaminants , exc
29、ept that it shall not include the use of abrasives or of solvents which are corrosive or that will deposit either corrosive or protective films. Care shall be taken that specimens are not re - contaminated after cleaning by excessive or careless handli ng. There shall be no craze lines, scratches, o
30、r breaks in the anodic coating in the area being tested. The temperature of specimens shall be stabilized at 24 +/ - 1 C. Test Procedure 1. Place the area to be tested in a horizontal position, facing up. 2. Attach the clamp with the pointed screw to the part to be tested and tighten the screw so th
31、at it breaks through the anodic coating and makes good contact with the basis aluminum. 3. Place the F.A.C.T. cell on the anodized surface and hold it down so that the gasket forms a seal to prevent the leakage of the electrolyte. 4. Fill the glass tube with the electrolyte to the specified level. F
32、ORD LABORATORY TEST METHOD BQ 007-01 Page 5 of 6 Copyright 2000, Ford Global Technologies, Inc. 5. Insert the clean anode rod in the electrolyte and immediately start the test by turning the switch to the TEST position. 6. Power is automatically applied to the FACT cell for 180 s. During this period
33、 the integrator is measuring and displaying the volt - seconds across the FACT cell. At the end of the TEST period, a buzzer sounds and power is removed from the FA CT cell. Reset the buzzer and record the number of volt - seconds displayed. This number is the FACT value. 7. Remove the anode rod fro
34、m the cell, rinse it with distilled or deionized water, wipe it with a clean tissue, and place it in a flask of distille d or deionized water for storage until the next test. 8. Remove the cell from the anodized surface and discard the electrolyte. 9. Rinse the cell with distilled or deionized water
35、. 10. Dry the bottom of the gasket so that it is ready for the next test. Interpretation of Results The area tested should be examined to make certain that the reaction appeared as spots rather than thin lines. Lines indicate that a scratched or crazed area has been tested; in that case, the test sh
36、ould be rerun. If exception ally high F.A.C.T. values are obtained, there may have been an insulating air bubble on the surface being tested. When this happens, the milliammeter reading will remain constant (at approximately 0.2 mA) during the test period; in that case, the bubble s hall be broken a
37、nd the test repeated. Run the second test on another section of the part, starting with Step 3 of this procedure. a. If the two F.A.C.T. numbers are within 10 % of the lower number, the average of the two numbers is the F.A.C.T. rating. b. If the two F.A.C.T. numbers vary between 10 and 30 % of the
38、lower number, run a third test. If the third number varies less than +/ - 30% of the lowest, the average of the two lowest numbers of the three is the F.A.C.T. rating. c. If the F.A.C.T. number s vary more than 30 % of the lowest, run a total of five tests. The average of the two lowest numbers of t
39、he five is the F.A.C.T. rating. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each par ty is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BQ 007-01 Page 6 of 6 Copyright 2000, Ford Global Technologies, Inc. FORD ANODIZED ALUMINUM CORROSION TEST ( F.A.C.T.) Figure 1 Diagram of Test Setup
