FORD FLTM EU-AQ 002-1-2001 CONTROL TESTS FOR ZINC PHOSPHATE COATING PROCESS.pdf

1、 FORD LABORATORY TEST METHOD EU-AQ 002-01 Date Action Revisions 2001 01 31 Revised Editorial no technical change A. Cockman 2000 04 19 Editorial no technical change A. Cockman 1994 02 28 Printed copies are uncontrolled Page 1 of 7 Copyright 2001, Ford Global Technologies, Inc. CONTROL TESTS FOR ZINC

2、 PHOSPHATE COATING PROCESS Application These test methods are used where applicable to check the concentration of the solutions used in the phosphate coating process. Solutions Required See FLTM EU-AZ 2-1 for preparation of solutions and indicators. Standard Sodium Hydroxide - 0.1 N Reagent No. 1 St

3、andard Hydrochloric Acid - 0.1 N Reagent No. 4 Standard Potassium Permanganate - 0.1 N Reagent No. 9 Standard Potassium Ferocyanide Reagent No. 12 Standard Ferrous Sulphate Solution - 0.1 N Reagent No. 10 Standard Sodium Thiosulphate Solution - 0.1 N Reagent No. 14 Standard Potassium Dichromate Solu

4、tion - 0.1 N Reagent No. 15 Indicators Phenolphthalein Reagent No. 101 Brom Cresol Green Reagent No. 108 Brom Phenol Blue Reagent No. 109 Sodium Diphenylamine Sulphonate (Oxidized) 0.002 g tablets Reagent No. 110 Iron Test Paper Reagent No. 111 Starch Solution Reagent No. 113 Orthophenanthroline Rea

5、gent No. 114 Methyl Orange Reagent No. 105 Apparatus Gas Evolution Tube Source: ICI Metal Pretreatment (Paint Division) Wexham Road Slough, Bucks FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 2 of 7 Copyright 2001, Ford Global Technologies, Inc. Conditioning and Test Conditions All test values indic

6、ated herein are based on material conditioned in a controlled 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 Test A - Cleaner Control Free Alkali 1. Pipette 10 mL of cleaner

7、solution into a 150 mL Erlenmeyer flask. 2. Add 5 drops of phenolphthalein indicator. 3. Titrate with 0.1 N HCl until solution changes from pink to colourless. mL of 0.1 N HCl used = Free Alkali Value Test A - Cleaner Control Total Alkali 1. Pipette 10 mL of cleaner solution into a 150 mL Erlenmeyer

8、 flask. 2. Add 10 drops of brom cresol green or methyl orange indicator. 3. Titrate with 0.1 N HCl until colour changes from purple red to yellow or yellow to pink respectively. mL of 0.1 N HCl used = Total Alkali Value Test B - Rinse Water Control Total Alkali (after alkaline cleaning) 1. Pipette 5

9、0 mL of rinse water into a 250 mL Erlenmeyer flask. 2. Add 5 drops brom cresol green or methyl orange indicator. FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 3 of 7 Copyright 2001, Ford Global Technologies, Inc. 3. Titrate with 0.1 N HCl to colour change. mL of 0.1 HCl used = Total Alkali Value If

10、solution turns yellow or red respectively after addition of indicator, this indicates that phosphate solution is getting into the rinse water, possibly through a misdirected nozzle. The solution is thus acid and should be tested according to the Total Acid method. Total Acid (after phosphating) 1. P

11、ipette 50 mL of rinse water into a 250 mL Erlenmeyer flask. 2. Add 5 drops phenolphthalein indicator. 3. Titrate with 0.1 N NaOH to pink colour. mL of 0.1 N NaOH = Total Acid Value Test C - Phosphate Coating Control Total Acid 1. Pipette 10 mL of phosphate solution into a 150 mL Erlenmeyer flask. 2.

12、 Add 5 drops of phenolphthalein indicator. 3. Titrate with 0.1 N NaOH to the development of a pink colour. mL of 0.1 N NaOH = Total Acid Value Test C - Phosphate Coating Control Free Acid 1. Pipette 10 mL of phosphate solution into a 150 mL Erlenmeyer flask. 2. Add 3 drops of brom phenol blue indica

13、tor. 3. Titrate with 0.1 N NaOH to a colour change from yellow to light blue. mL of 0.1 N NaOH used = Free Acid Value FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 4 of 7 Copyright 2001, Ford Global Technologies, Inc. Accelerator Test Nitrite and Peroxide Type Before testing for the amount of accele

14、rator, dip a strip of iron test paper in phosphate solution. If the paper turns pink, it is an indication that no accelerator is present. Small additions of accelerator should be made to the phosphate solution tank until no change in colour of a fresh indicator paper occurs. When no change in colour

15、 of the test paper appears, proceed to determine the amount of accelerator as follows: 1. Pipette 50 mL of the filtered phosphate solution into a 250 mL Erlenmeyer flask. 2. Add 10 mL of 50 % H2SO4 solution. 3. Titrate with standard 0.1 N KMnO4 drop by drop while swirling, until a persistent pink co

16、lour is obtained which remains for 15 seconds. mL of KMnO4 = Total Accelerator Value Chlorate Type 1. Fill the gas evaluation apparatus with phosphate solution (see sketch). 2. Tilt apparatus to release entrapped air from the calibrated closed end. Add sufficient phosphate solution to fill the tube

17、again. 3. Add approximately 4 grams of sulphamic acid crystals and immediately invert the tube so that most of the sulphamic acid runs into the calibrated closed end of the tube. 4. Place the tube in its cradle in an upright position and leave for one minute. Gas volume evolved = Total Accelerator V

18、alue Phosphate Test - Based on Zinc Content of Bath 1. For nitrite and peroxide accelerated systems and 1 mL of 0.1 N kMnO4 to the sample just titrated for accelerator test. If chlorate accelerated take 50 mL sample of filtered phosphate solution, acidify with 10 mLs of 50 % H2SO4 solution and add d

19、ropwise from a dropping bottle 0.1 N kMnO4 until persistent pink colour is obtained. 2. Add 3 drops of 1 % solution of potassium ferocyanide and then 0.002 g of sodium diphenylamine sulphonate oxidized (tablet form) indicator and allow to dissolve. FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 5 of

20、7 Copyright 2001, Ford Global Technologies, Inc. 3. Slowly add a solution consisting of 65.2 g of potassium ferocyanide and a 0.5 g sodium carbonate per litre of distilled water from a burette with constant stirring until the colour changes from violet to light blue, then add dropwise until permanen

21、t green (15 seconds). mLs of potassium ferocyanide used = Total Zinc Value Note: Alternatively a compleximetric titration method can be used. The method must be coordinated between supplier of zinc phosphate coating material and consumer. Test D - Chromic - Phosphoric Rinse Control Free Acid 1. Pipe

22、tte 100 mL of rinse solution into a 250 mL Erlenmeyer flask. 2. Add 4 drops of brom cresol green indicator. Note: If the colour of the sample turns from yellow to green after adding indicator, it indicates that no free acid is present; that additional chromic-phosphoric acid should be added to the r

23、inse tank and another test made. 3. If the solution remains yellow, titrate to a green colour with 0.1 N NaOH. Note: Save sample for Total Acid Test. mL of 0.1 N NaOH = Free Acid Value Total Acid 1. Add 5 drops of phenolphthalein to the sample used in the Free Acid Test and continue titrating with 0

24、.1 N NaOH to a violet colour which will last for 15 seconds. 2. The total number of mL of 0.1 N NaOH used in the Free Acid Value plus the above value = Total Acid Value. Test E - Hexavalent Chromium Two optional methods are shown: Method 1 1. Pipette 25 mL of the rinse sample into a 250 mL Erlenmeye

25、r flask with glass stopper and dilute to 100 mL with distilled water. 2. Add approximately 1 g of potassium iodide and agitate until dissolved. FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 6 of 7 Copyright 2001, Ford Global Technologies, Inc. 3. Add carefully 15 mL of HCl (concentrated) and stopper

26、 the flask. 4. After 1 minute titrate the solution with 0.1 N sodium thiosulphate until a straw colour is obtained (Reagent No. 14). 5. Add 3 - 5 mL of soluble starch solution (Indicator No. 113) and continue the titration until the blue-black colour disappears. 6. The total number of mL of titratin

27、g solution used is the points of hexavalent chromium present. Method 2 1. First be sure that the free acid is in the operating range. 2. Pipette 25 mL of rinse sample into a 250 mL beaker and add 25 mL of H2SO4 (50 %). 3. Add 35 mL of distilled water and 2 drops of orthophenanthroline (Indicator No.

28、 114). 4. Titrate with 0.1 N ferrous sulphate (Reagent No. 10) until the solution changes through blue to a reddish brown colour. Calculate pointage of hexavalent chromium as follows: Pointage = mL 0.1 N FeSO4 x C (correction factor) Note: The 0.1 N FeSO4 is not stable and must be standardized weekl

29、y to determine its correction factor “C“ as follows: (a) Pipette 10 mL of 0.1 N potassium dichromate solution into a 250 mL beaker. (b) Add 25 mL of H2SO4 (50 %), 50 mL of distilled water and 2 drops of orthophenanthroline. (c) Titrate with 0.1 N FeSO4 solution until the colour changes through blue

30、to a reddish brown colour. Correction Factor “C“ = 10 (mL dichromate) mL of Ferrous Sulphate used 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. FORD LABORATORY TEST METHOD EU-AQ 002-01 Page 7 of 7 Copyright 2001, Ford Global Technologies, Inc. CONTROL TESTS FOR ZINC PHOSPHATE COATING PROCESS