FORD FLTM AQ 101-1-2001 DETERMINATION OF PHOSPHATE COATING WEIGHTS - CHROMIC ACID METHOD (Replaces FLTM EU-AQ 001-01).pdf

1、 FORD LABORATORY TEST METHOD AQ 101-01 Date Action Revisions 2001 01 31 Revised Editorial no technical change A. Cockman 2000 04 20 Editorial no technical change A. Cockman 1990 01 17 Printed copies are uncontrolled Page 1 of 4 Copyright 2001, Ford Global Technologies, Inc. DETERMINATION OF PHOSPHAT

2、E COATING WEIGHTS - CHROMIC ACID METHOD Application This procedure is used to determine the coating weight of iron, zinc or manganese phosphate used on iron or steel parts. Two methods are described in this procedure: Method A - employing test panels to check a phosphate coating system, and Method B

3、 - employing actual parts (primarily threaded fasteners) to determine the weight of phosphate on a submitted part. Materials and Solutions Required Chromic Acid Stripping Solution Dissolve 200 g of CrO3 in 500 ml of water and dilute to 1000 ml. Transfer the solution to a two-liter beaker and heat to

4、 93 C for stripping the coatings from the panels. Test Panels for Method A The test panels are 100 mm by 300 mm steel body stock (CRLC, Class A finish). Process two panels through a complete cycle of the phosphate coating system under test, including cleaning, phosphating, acid rinse (if required) a

5、nd drying. Test Parts for Method B Three or more actual production parts taken at random should be obtained from the lot, batch, etc., being evaluated. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50

6、+/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure Method A 1. Buff the 100 mm by 300 mm panels on the back or unexposed surface to remove any phosphate coating. Use a soft rag wheel for this purpose. FORD LABO

7、RATORY TEST METHOD AQ 101-01 Page 2 of 4 Copyright 2001, Ford Global Technologies, Inc. 2. Cut a 100 mm by 100 mm section from each of the buffed panels for determination of coating weight. Deburr after cutting. 3. Remove any grease or foreign matter from the test specimens by washing with ether, ac

8、etone and ethanol. Pouring a mixture of the three solvents over the test specimens should remove any soil. 4. Blot the test specimens with a soft cloth and then dry in an oven at 100 +/- 2 C for five minutes. 5. Cool in a desiccator and weigh the test specimens to the nearest milligram. 6. Immerse t

9、he test specimen in the chromic acid stripping solution for approximately 90 seconds. 7. Rinse the test specimens in running water. Blot and then dry in an oven at 100 +/- 2 C. 8. Cool in a desiccator, reweigh and repeat Steps 6, 7 and 8 to constant weight. Calculations loss in wt. (mg) = mg of coat

10、ing surface area of test specimen (sq. mm.) per sq. mm. NOTE: The chromic acid solution should be renewed after twelve 100 mm by 100 mm test specimens have been stripped as phosphoric acid tends to build up in the solution after prolonged use and attacks the metal. For calculating the coating weight

11、, mg/m2. Wc = (W o - W i) x 106 A Wc = Coating weight mg/m2 Wo = Weight of panel before stripping in solution, mg Wi = Weight of panel after removal of coating, mg A = Area of panel, mm2 Method B 1. Obtain a minimum of three threaded fasteners from the lot in question after they have been processed

12、through a complete cycle of the phosphate coating system, including cleaning, phosphating, acid rinse (if required) and drying. FORD LABORATORY TEST METHOD AQ 101-01 Page 3 of 4 Copyright 2001, Ford Global Technologies, Inc. 2. Remove any grease or foreign matter from the test specimen by washing wi

13、th ether, acetone and ethanol. Pouring a mixture of the three solvents over the test specimens is expected to remove any soil. 3. Blot the test specimens with a soft cloth and then dry in an oven at 100 +/- 2 C for five minutes. 4. Cool in a desiccator and weigh the test specimens to the nearest mil

14、ligram. 5. Immerse the test specimens in the chromic acid stripping solution for approximately 90 seconds. 6. Rinse the test specimens in running water. Blot and then dry in an oven at 100 +/- 2 C. 7. Cool in a desiccator, reweigh and repeat steps 5, 6 and 7 to constant weight. Calculations Procedur

15、e for determining surface area of threaded fasteners:* A. Area of threaded portion of fastener: At = 2 p L (r1 - r2) Where L = length of threaded portion, mm r1 = major radius, mm r2 = minor radius, mm p = 3.14159 FORD LABORATORY TEST METHOD AQ 101-01 Page 4 of 4 Copyright 2001, Ford Global Technolo

16、gies, Inc. B. Area of “ends“: Ae = 2 p d2 4 Where d = diameter of head, mm C. Area of sides of head: As = p d h Where d = diameter of head, mm h = length of head, mm D. Area of sides of driving hole: Ah = p d1 h1 or Ah = 2 p d1 h1 (for “Torx“ Recess) Where d1 is the maximum driving hole diameter, mm

17、 h1 is the driving hole depth, mm E. Area of fastener: sq. mm *fastener = At + Ac + As + Ah * Alternate Method: Use National Association of Metal Finishers Table D-5 and D-7 to obtain areas of threaded round stock, bolt head tops, bolt head sides and bolt ends (circles). Coating Weight loss in weigh

18、t (mg) = mg of coating per sq mm surface area of fastener (sq. mm) The average of the three fasteners shall be reported as the coating weight of the test parts. To calculate mg/m2, use dimensions and multiply by 106. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.