1、 FORD LABORATORY TEST METHOD AI 001-01 Date Action Revisions 2000 08 07 Editorial no technical change A. Cockman 1992 04 27 Printed copies are uncontrolled Page 1 of 4 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF PERCENT ZINC IN WELDING PRIMERS Application Part 1 of this procedure
2、 is used to separate the pigment from vehicle, binders and solvents in paints. Part 2 describes the procedure for the determination of percent zinc in welding primers. An information page is attached to this procedure which lists common pigments and extraction mixtures which may be used for separati
3、on of these pigments. Equipment Required Centrifuge* Centrifuge Tubes Pear shaped - 100 mL capacity Laboratory Oven Rec irculating - 250 F capacity Sieve No. 80 Analytical Balance Sensitivity .001 g *Some pigments are so finely dispersed that a super centrifuge of extremely high velocity is required
4、. These pigments cannot be separated by this method. Chemicals Required Extraction Mixture “A“ 10 volumes ethyl ether 6 volumes benzol 4 volumes methyl alcohol 1 volume acetone Extraction Mixture “B“ 5 volumes benzol 4 volumes methyl alcohol 1 volume acetone Extraction Mixture “C“ 1 volume toluene 1
5、 volume acetone FORD LABORATORY TEST METHOD AI 001-01 Page 2 of 4 Copyright 2000, Ford Global Technologies, Inc. Reagents Required Standard Potassium Permanganate (0.1 N KMnO 4 ) (Standardize per Ford Laboratory Test Method AZ 2 - 1, Reagent 9) Sodium Acetate Solution (200 g/liter) Dissolve 200 g of
6、 NaC 2 H 3 O 2 or 332 g of NaC 2 H 3 O 2 - 3H 2 O and dilute to 1 liter. Ferric Chloride Solution Prepare a solution containing 20 g of FeCl 3 - 6H 2 O and 20 mL of the NaC 2 H 3 O 2 solution per 100 mL (one day supply only). Zimmerman Reinhardt Solution Prepare a solution containing 67 g of Mn SO 4
7、 - 4H 2 O, 130 mL of H 2 SO 4 (sp. gr. 1.84) and 138 mL o f H 3 PO 4 (85 %) per liter. 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 humidity for not less than 24 h prior to testi
8、ng and t ested under the same conditions unless otherwise specified. Procedure - Part 1 - Pigment Separation 1. Place approximately 15 g of the well agitated sample into a centrifuge tube and add 20 to 30 mL of a suitable extraction mixture. Note: It may be nec essary to try several of the listed ex
9、traction materials, depending on the type of resins in the paint formulation. 2. Stir well with a glass rod and wash the rod with a quantity of the extraction mixture to result in 60 mL of solution in the tube. 3. Pl ace the tube in the centrifuge, counterbalance and spin for 15 minutes at moderate
10、speed or until the sample is well settled. 4. Decant the clear supernatant liquid and repeat the extraction twice with 40 mL of the extraction mixture and once with 40 mL o f ether. 5. After drawing off the ether, hold the tube in a nearly horizontal position, tap the side of the tube to dislodge th
11、e pigment cake from the bottom of the glass tube and set the tube in a beaker of water at 23 +/ - 2 C. 6. Gradually raise the t emperature by placing the beaker on top of a warm oven for 10 minutes. Pour off water; then place the beaker in the oven at 105 110 C for 2 h. FORD LABORATORY TEST METHOD A
12、I 001-01 Page 3 of 4 Copyright 2000, Ford Global Technologies, Inc. Procedure - Part 1 - Pigment Separation (Continued) 7. Cool in a desiccator. 8. Grind the pigment to a fin e powder and pass through a No. 80 sieve to remove any “skins“. Completion of these steps will effect separation of the pigme
13、nt from vehicles and binders and concludes Part 1. Procedure - Part 2 - Determination of Metallic Zinc 1. Weigh out 0.200 g of the previously separated pigment (zinc) and transfer immediately to a 600 mL heavy wall Erlenmeyer flask. Note: If this procedure is to be used on unextracted pigment, dry a
14、 quantity in the laboratory oven for 2 h at 100 C. 2. Add 50 mL of the FeCl 3 so lution to the flask, stopper tightly and agitate constantly for 15 minutes. 3. As soon as the zinc dust is completely dissolved, add 50 mL of the Zimmerman Reinhardt solution, 250 mL of water and titrate with KMnO 4 sol
15、ution. 4. Run a blank by mixing 50 m L of the FeCl 3 solution and 50 mL of the Zimmerman Reinhardt solution. Titrate with the standard KMnO 4 solution. (The blank is usually 0.1 to 0.2 mL of .1 N KMnO 4 solution.) Calculation Calculate percent metallic zinc as follows: Metallic zinc perce nt = (A -
16、B) N x 0.0327 x 100 C A = Milliliters of KMnO 4 solution required for titration of the sample. B = Milliliters of KMnO 4 solution required for titration of the blank. N = Normality of the KMnO 4 solution. C = Grams of sample used. Chemicals, ma terials, parts, and equipment referenced in this docume
17、nt must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD AI 001-01 Page 4 of 4 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF PERCENT ZINC IN WELDING PRIMERS INFORMATION SHEET The fo llowin
18、g common pigments may usually be extracted from linseed oil paints and pastes by means of the reagents and procedures indicated below: Group 1 All white pigments Ultramarine blue Metallic brown Chromium oxide green Chrome yellow Chrome orange Bright red, Indian red and mineral red iron oxides Veneti
19、an red Yellow ocher Yellow iron oxide Extract with extraction mixture “A“. If the pigment does not settle readily, extract with petroleum ether. Group 2 Lamp black Carbon black Bone black Umbers and sie nnas Extract with petroleum ether. Group 3 Chrome green Iron blue Extract with extraction mixture
20、 “B“. If the pigment does not settle readily with this mixture, proceed as follows: Place 10 to 15 g of the sample in a weighed centrifuge tube (having a capacity of approximately 75 milliliters). Add 5 milliliters of V.M.&P. naphtha and stir with a glass rod. Add 45 milliliters of hot absolute ethy
21、l alcohol. Stir thoroughly and, while stirring, keep the mixture hot by placing the tube in a water or stea m bath. Remove the stirring rod and wash any adhering pigment back into the tube with hot alcohol. Centrifuge at a moderate speed for approximately 2 minutes. (The pigment settles readily.) Pour off the solvent and oil and rinse the tube with hot alcoh ol without disturbing the packed pigment in the bottom of the tube. Repeat the extraction three times, making a total of four extractions. Dry tube and contents at 105 - 110 C overnight or until a constant weight is obtained.
