1、FORD LABORATORY TEST METHOD BL 105-01 2001 0822 A RAPID METHOD TO PREDICT THE EFFECTIVENESS OF INHIBITED COOLANTS IN ALUMINUM HEAT EXCHANGERS Revised Editorial - no technical change A. Cockman Application This test is used to predict the effectiveness of engine coolants in preventing pitting and cre
2、vice attach of aluminum heat exchanger alloys. The test measures the pitting potential (Ep) of aluminum alloys in an engine coolant. Apparatus Required Galvanostat Princeton Applied Research Model 173 PotentiostaGalvanostat or any equivalent instrument capable of providing a current (adjustable) of
3、approximately 1 milliamp. Source: EG&G Instruments 310 Melvin Drive Northbrook, Illinois 60062 Recorder, Strip Chart Soltec, Model VP-62315, or equivalent. Source: Soltec Corporation 11684 Pendleton Street Sun Valley, California 91 352 Polarization Cell (See schematic for details of cell constructio
4、n) 1. Pyrex #25 Oring Joint (No. 6780), Plain, and Viton Orings to fit, available from VWR Scientific. 2. Ball Joint Clamp, #35, available from VWR Scientific. 3. Spectrographic grade graphite electrode, 152 X 6.35 mm diameter. Source: Ultra Carbon Corporation Bay City, Michigan 48707 4. Calomel ele
5、ctrode, saturated, fiber type, Corning 476002 or equivalent, available from VWR Scientific. I Date I Action I Revisions I Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BL 105-01 5. Luggin Capillary Surface Processing Department Scientific Research Laboratory Ford Motor Com
6、pany Dearborn, Michigan 48123 Gum Rubber Tubing Size dependent upon size of Luggin Capillary, available from VWR Scientific. Rubber Stopper One hole stopper (size dependent upon size of Luggin Capillary), available from VWR Scientific. Materials Required Sodium Chloride NaCI - Reagent grade. Distill
7、ed or Deionized Water 10 ppm max dissolved solids (ASTM D 1888). Acetone Reagent grade. Caution: Low flash point. Aluminum Test Specimen AA 7072 or an AA 7072 cladding over a core alloy such as the Alcad alloy series. Minimum specimen size is 40 x 60 mm. Conditioning and Test Conditions All test val
8、ues 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 testing and tested under the same conditions unless otherwise specified. Procedure Preparation of Coolant Mixt u re Prepare 200 mL of cool
9、ant solution sufficient for triplicate tests. Mix 50 mL of the coolant concentrate in 150 mL of distilled or deionized water. To this mixture add 33 mg of sodium chloride (NaCI), either as the salt or as an aliquot from a previously prepared standard sodium chloride solution. This will give 100 ppm
10、of chloride ions in the final mixture. Page 2 of 5 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BL 105-01 Preparation of Aluminum Test Specimen Degrease samples with acetone and let dry. Assemble test specimen into test cell according to Figure 1. Test Cell Operation 1. 2
11、. 3. 4. 5. 6. Fill cell with 50 mL of test coolant, and attach the plexiglass lid containing the Luggin capillary and graphite counter electrode. It is important that the spacing between the Luggin capillary tip and the working electrode should always be adjusted to a working distance of 1 mm, as de
12、termined by a calibrated spacer, to minimize IR drop difference between coolant samples. Using gum rubber tubing attached to a one-hole rubber stopper, suction the coolant level above the ground glass stopper making sure the ground glass stopper surface is thoroughly wetted. Close stopper and place
13、calomel (reference) electrode tip in coolant reservoir above stopper. Attach leads from galvanostat to the working, counter and reference electrodes. Polarize working electrode with 1 O0 microamps/cm2 of anodic current, and record potential-time transient. The area of the working electrode for the c
14、ell in Figure 1 is 8.2 cm2. Therefore, a total of 820 microamps is applied. It is important that the time between introduction of test coolant into the test cell and polarization be kept constant at 5 minutes to avoid inconsistent results. After the initial potential spike (film breakdown and pit in
15、itiation) following specimen polarization, the potential will generally decay into one of the more common transients shown in Figure 2. The pitting potential is indicated for each type of transient and is associated with the most negative or active potential. Polarization may be discontinued when E,
16、 is apparent (type “A and “B“ transients). If a type “C“ transient is obtained, continue polarization for 1 h. Three independent polarizations are required for each mixture using a new aluminum sample for each. Use the mean of the three values for the final pitting potential. General Information It
17、is essential that engine coolant formulations prevent localized corrosion attack in aluminum radiators and heater cores. This test is used to predict the effectiveness of engine coolants in preventing pitting and crevice attack of aluminum heat exchanger alloys. An increase in the effectiveness is a
18、ccompanied by an increase in the pitting potential (Ep) to more positive or hnoble values. The test is rapid (approximately 1 h), and shows excellent correlation with the 50,000 mile, 4 month Simulated Service Circulation Test (SSCT), using full-size engine cooling system components. Data showing th
19、e correlation of this rapid test and the SSCT is contained in Ford Research Technical Report SR-80-67 and SAE Technical Paper 800800. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and han
20、dling in its facilities. Page 3 of 5 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BL 105-01 A RAPID METHOD TO PREDICT THE EFFECTIVENESS OF INHIBITED COOLANTS IN ALUMINUM HEAT EXCHANGERS Schematic of Galvanostatic Polarization Cell TO S.C.E. REFERENCE ELECTRODE GROUND GLAS
21、S STOPCOCK 12/5 BALL AND SOCKET GROUND JOINT PLEXIGLAS LID COUNTER ELECTRODE GRAPHITE ROD #25 O-RING JOINT LUGGIN CAPILLARY 1 .O mm SPACE BETWEEN LUGGIN &WORKING ELEC VITON O-RING J -WORKING ELECTRODE ALUMINUM SPECIMEN TRODE Figure 1 Page 4 of 5 Copynght02001, Ford Global Technologies, Inc FORD LABO
22、RATORY TEST METHOD BL 105-01 A RAPID METHOD TO PREDICT THE EFFECTIVENESS OF INHIBITED COOLANTS IN ALUMINUM HEAT EXCHANGERS Most Common Potential/Time Transients After Polarization (Pitting Potential, E, is Indicated for Each Type of Transient) SPECIMEN POLARIZED 0.5 TIME, HR Figure 2 Page 5 of 5 Copynght02001, Ford Global Technologies, Inc
