1、 FORD LABORATORY TEST METHOD AQ 150-01 Date Action Revisions 2001 01 31 Revised Editorial no technical change A. Cockman 2000 04 25 Editorial no technical change A. Cockman 1994 07 22 Printed copies are uncontrolled Page 1 of 3 Copyright 2001, Ford Global Technologies, Inc. TEST FOR PHOSPHATE CONTAM
2、INATION OF HIGH STRENGTH SCREWS Application This method is used to inspect the surfaces of high strength screws for P205 contamination, which results in brittleness. Note: This method is based on the reduction of molybdate-phosphate with ascorbic acid producing a blue complex (molybdenum blue) which
3、 is stable at 23 +/- 2 C for about four hours. Apparatus and Reagents Required 1. Test Solution - Ammonium-molybdate/Sulphuric acid Preparation: Dissolve 10 g (NH4)6 Mo7 O24 .4 H2O A.R. (ammonium-molybdate) in distilled water and make up to 100 mL. Add the solution to 300 mL of H2SO4 (50 % by weight
4、) and cool to 23 +/- 2 C. 2. Test Salt - Ascorbic Acid A.R. 3. 1 N H2SO4 4. 1 N NaOH 5. Standard Solution Preparation: Dissolve 0.1917 g KH2PO4 A.R. (potassium-dihydrogenphosphate) in 1000 mL of deionized water. This standard solution contains 100 mg/L P2O5. 6. Graduated Cylinders (10 mL, 50 mL, 5 x
5、 100 mL); beakers (250 mL tall form, 400 mL short form); graduated pipettes; 200 mL volumetric flask; lifting tongs or forceps. 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 % relative humidit
6、y for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. FORD LABORATORY TEST METHOD AQ 150-01 Page 2 of 3 Copyright 2001, Ford Global Technologies, Inc. Procedure 1. Measure 25 mL of 1 N H2SO4 into a 400 mL beaker. 2. Immerse a sufficient number of
7、screws to give a test surface area of 15 cm2in the 1 N H2SO4 for about 10 seconds at 23 +/- 2 C. 3. Add 25 mL of 1 N NaOH to neutralize the solution. 4. Take the screws out of the solution using forceps or lifting tongs allowing the solution to drop off the screws. 5. Pipette 8 mL of test solution (
8、ammonium-molybdate/sulphuric acid) into the neutralized solution and add 0.2 g of test salt (ascorbic acid). 6. Shake the beaker for a short time, and then heat the solution to boiling for about 1 minute. 7. Cool the solution and transfer it to a 100 mL graduated cylinder. 8. Compare the developed b
9、lue coloring of the solution with the color of the reference solutions which are prepared as described below. Note: If this method indicates more than 0.1 mg P2O5 on the surface of the screws (15 cm2), it must be assumed that the screws have not been sufficiently cleaned to remove phosphate contamin
10、ation. Preparation of the Reference Solutions 1. Pipette 20 mL of the standard solution (potassium-dihydrogenphosphate solution) into a graduated 200 mL flask. 2. Dilute the solution with about 100 mL of distilled water. 3. Add 8 mL of the test solution (ammonium-molybdate/sulphuric acid) using a gr
11、aduated pipette, and then add about 0.2 g of the test salt (ascorbic acid). 4. Shake the volumetric flask for a short time and then heat the solution and hold at boiling point for about 1 minute. (The color of the solution turns to blue.) 5. Cool the solution and fill the volumetric flask with disti
12、lled water up to the standard mark. FORD LABORATORY TEST METHOD AQ 150-01 Page 3 of 3 Copyright 2001, Ford Global Technologies, Inc. 6. Shake the volumetric flask to mix the solution. The concentrated, colored solution is used to produce 4 reference solutions which differ both in content of P2O5 and
13、 in intensity of blue coloring. 7. Place the following constituents in the four 100 mL graduated cylinders. Cyl. 1 Cyl. 2 Cyl. 3 Cyl. 4 Concentrated colored solution, mL 2 5 10 20 (measured with a pipette) Distilled Water, mL 56 53 48 38 P2O5 content, mg 0.02 0.05 0.1 0.2 8. Shake the cylinders to m
14、ix the colored solutions. Note: The concentrated colored solution as well as the dilute solutions must be freshly produced, and used within 4 hours. 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.
