1、Designation: D7934/D7934M 14Standard Test Method forCorrosion of Cast Aluminum Alloys in Non-Aqueous EngineCoolants Under Heat-Rejecting Conditions1This standard is issued under the fixed designation D7934/D7934M; the number immediately following the designation indicates theyear of original adoptio
2、n or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a laboratory screening proce-dure for evaluating th
3、e effectiveness of non-aqueous enginecoolants in combating corrosion of aluminum casting alloysunder heat-transfer conditions that may be present in aluminumcylinder head engines.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated
4、ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard. Some values have only SI units because theinch-pound equivalents are not used in practice.1.3 This standard
5、 does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Some specifichazards statements
6、 are given in Sections 11 and 12.2. Referenced Documents2.1 ASTM Standards:2D1176 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants orAntirusts for Testing PurposesD4340 Test Method for Corrosion of Cast Aluminum Alloysin Engine Coolants Under Heat-Rejecting Conditions3. Summ
7、ary of Test Method3.1 In this test method, a heat flux is established through acast aluminum alloy typical of that used for engine cylinderheads while exposed to a non-aqueous engine coolant under apressure of 34.5 kPa 5 psig. The temperature of the aluminumspecimen is maintained at 149C 300F and th
8、e test iscontinued for 1 week (168 h). Effectiveness of the coolant forpreventing corrosion of the aluminum under heat-transferconditions (hereafter referred to as heat-transfer corrosion) isevaluated on the basis of the weight change of the testspecimen.4. Significance and Use4.1 It is essential th
9、at engine coolants prevent heat-transfercorrosion of aluminum cylinder heads during engine operation.Any corrosion products formed may deposit on interior radia-tor surfaces, reducing heat-transfer efficiency of the radiator.Overheating and boil-over of the cooling system may thenoccur.4.2 This test
10、 method provides a means for selectivelyscreening unused non-aqueous engine coolants and will readilydistinguish those coolants that are unsuitable for use withaluminum cylinder head engines. However, satisfactory perfor-mance of a coolant in this test method does not ensure adequatelong-term servic
11、e performance. Additional, more comprehen-sive evaluations with simulated service, dynamometer, andvehicle tests should be used to establish the long-term effec-tiveness of the coolant.5. Apparatus5.1 Heat-Transfer Corrosion CellThe assembled corro-sion cell is shown schematically in Fig. 1. It is a
12、ssembled fromcomponents, some of which require glass blowing or machin-ing. The glass O-ring cell shall be constructed from two glassO-ring joints3joined to an additional middle section of glasstubing4of the same diameter to make a total length of 53 cm21 in. Heat-resistant O-rings5shall be used. In
13、ternal pressureshall be monitored using a suitable pressure gage, and apressure-relief valve shall be installed to protect againstbursting.5.1.1 The top assembly plate (shown in Fig. 2) shall beconstructed of stainless steel, and the heat-transfer bar and1This test method is under the jurisdiction o
14、f ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.22 on Non-Aqueous Coolants.Current edition approved June 1, 2014. Published September 2014. DOI:10.1520/D7934_D7934M142For referenced ASTM standards, visit the ASTM website, www.astm.org, or
15、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3O-ring joints with a low coefficient of expansion may be used.4High-strength glass with a low coefficient of expansion may be used.5
16、Silicone O-rings may also be satisfactory. Polytetrafluoroethylene is notsuitable due to a high creep rate at the test temperature.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1bottom assembly plate (also illustrated in Fig. 2) shal
17、l prefer-ably be constructed of stainless steel. Mild steel may be usedfor the heat-transfer bar and bottom assembly plate.5.2 Temperature Controller, with high-temperature alarmoption and temperature control range up to at least 177C350F. Use Type J thermocouple. A heavy-duty electricalpower relay
18、or SCR solid-state contactor is connected to thetemperature controller to carry the current load to the bandheaters.5.3 Electrical Relay, 30-amp rating. The relay is changedafter about every 50 000 cycles to prevent contact welding.5.4 Band Heaters, at least 950 W, 120-V ac, 5.1-cm 2-in.inside diame
19、ter, 12.7-cm 5-in. length.5.5 Ultrasonic Cleaner, about 50 W, for cleaning aluminumtest samples.5.6 Vacuum Oven, with temperature range up to about150C 302F for thoroughly drying cast aluminum samples.5.7 Vacuum Pump, for use with vacuum oven.5.8 Thermal Cutoff, for over-temperature protection, loca
20、ted1.3 cm 12 in. from the heat-transfer bar.5.9 Compressed Air, for pressurizing test cell.5.10 Clear Plastic Safety Shield, for protection againstbursting.NOTE 1The apparatus required for Test Method D7934/D7934M isthe same as that required for Test Method D4340. Test Method D4340Section 5 Apparatu
21、s includes possible component sources. Completeapparatus for Test Method D4340 is offered by internet sources.6. Sampling6.1 The non-aqueous engine coolant shall be sampled inaccordance with Test Method D1176.7. Metal Test Specimen7.1 Cast Aluminumconforming to UNS A031906is used.Specimen size is 6.
22、5 cm 2.6 in. in diameter, 1.3 cm 0.5 in.thick. Fig. 2 illustrates location of the thermocouple holes.8. Test Solution8.1 Dissolve 13.2 mg of reagent grade sodium chloride in 60mL of distilled or deionized water, and then add 940 mL of thenon-aqueous test coolant. This is sufficient solution for twot
23、ests.9. Test Conditions9.1 The aluminum heat-transfer specimen temperature ismaintained at 149 6 1C 300 6 2F throughout the test bymeans of a thermocouple connected to the temperature con-troller. The thermocouple is inserted into one of the thermo-couple holes in the test specimen. The other thermo
24、couple holeis used for occasional precise temperature measurements.9.2 The test is run continuously for one week (168 h).9.3 A pressure of 34.5 kPa 5 psig is maintained on the testcell.9.4 Duplicate tests are required.10. Preparation of Test Specimen10.1 The following steps are necessary in the prep
25、aration ofthe aluminum test specimen for maximum repeatability andreproducibility:10.2 Polish the test specimen progressively with coarse-,medium-, and fine-grit emery cloth or paper, and finally with600-grit paper.10.3 Wash the test specimen with warm tap water, then rinsewith distilled or deionize
26、d water, and finally with acetone.Make sure thermocouple holes are free of metal chips andpolishing debris. Flush the holes with acetone and removeexcess liquid with a glass capillary pipet or other suitablemeans.10.4 Dry the test specimen in a vacuum oven for a minimumof4hat65to90C 149 to 194F to r
27、emove residual liquidthat may be retained in a porous casting. From this point, usethin cotton gloves, or equivalent, to handle the specimen toavoid weighing errors.10.5 Remove the specimen from the oven and allow it tocool to room temperature in a desiccator.10.6 Weigh the specimen to 0.1 mg using
28、an analyticalbalance. The test sample may be reused if desired, but shall beprepared in accordance with 10.1 10.6.11. Procedure11.1 AssemblyAssemble the cell in accordance with Fig.1. Use new O-rings between the aluminum test specimen andglass cell for each test. To help ensure that the O-rings arep
29、roperly seated, apply a small amount of the test solution to the6Metals and Alloys in the Unified Numbering System (UNS), SAE-ASTM,Fourth Edition.FIG. 1 Heat-Transfer Corrosion Test AssemblyD7934/D7934M 142glass O-ring groove for lubrication. Avoid over-tightening ofthe threaded rod nuts.11.2 Starti
30、ng the TestTransfer 500 mL of test coolantsolution into the test cell, screw the plug in the hole, andtighten. Place the safety shield around the cell, (WarningSee11.2) pressurize the cell to 34.5 kPa 5 psig with compressedair, and turn the band heater on. Maintain the pressure at 34.5kPa 5 psig. (W
31、arningDespite the presence of a safetyrelief valve, test cells have burst under pressure. Use of a safetyshield is absolutely necessary.Aclear plastic enclosure, havingallowance for adequate circulation of air yet completelysurrounding the test apparatus has been successfully used forthis purpose.)1
32、1.3 Conducting the TestAdjust the temperature to 149 61C 300 6 2F with the temperature controller. Monitor thetemperature at the auxiliary thermocouple hole at periodicintervals with a precision potentiometer. Operate the cellcontinuously at this temperature for 1 week (168 h).11.4 Terminating the T
33、estAt the end of the test period,turn off the heater and allow the cell to cool to roomtemperature before disassembly. Release pressure, remove thefill plug, and pour or siphon out the test coolant.11.5 After disassembly, clean the cell with a large bristlebrush rotated by an electric drill motor, p
34、umice powder,detergent, and water.12. Cleaning of Aluminum Test Specimen12.1 Wash the specimen with a soft bristle brush using amild detergent. Remove any O-ring residue by gentle scrapingwith a material that is softer than the aluminum (for example,a thick piece of polyethylene or polypropylene wit
35、h a freshlysheared edge).12.2 In a fume hood, immerse the specimen for exactly 10min in an aqueous solution containing four parts concentratednitric acid (70 % by weight) plus one part water at 25C 77F.Occasionally brush the surface with a soft bristle brush. After10 min, transfer the beaker contain
36、ing the aluminum specimenand cleaning solution to an ultrasonic cleaning unit. Applypower for 1 min. (WarningNitric acid is a strong oxidant.Avoid contact with skin, eyes, and clothing. Do not breathevapor.)12.3 Remove the specimen from the cleaning solution, flushwell with tap water, then with dist
37、illed or deionized water, andfinally with acetone. Make sure thermocouple holes are flushedwell and excess liquid is removed. Inspect the surface using amicroscope with a magnification range from 10 to 30. If anydeposits remain, repeat 12.2 and 12.3.12.4 Dry the specimen in a vacuum oven using the s
38、ameprocedure and precautions in accordance with 10.4.12.5 Cool the specimen to room temperature in a desiccatorand weigh to the nearest 0.1 mg.13. Determination of Blank Correction13.1 Clean and weigh at least three unused specimens inaccordance with 12.1 12.5.13.2 Use the average weight loss as the
39、 blank correction,provided the deviations are not significant.14. Calculation14.1 Calculate the heat-transfer corrosion rate (R) as fol-lows:R 5Wb2 Wa1 B! 3 1000A(1)FIG. 2 Heat-Transfer Corrosion Test ComponentsD7934/D7934M 143where:R = corrosion rate, mg/cm2/week,Wb= weight of test specimen before
40、test, g,Wa= weight of test specimen after test, g,B = weight loss of blank, g, andA = heat-flux surface area inside O-ring, cm2.15. Report15.1 Report the following information:15.1.1 Report the heat-transfer corrosion rate to the nearest0.1 mg/cm2/week of each specimen.15.1.2 The appearance of each
41、specimen, such as pitting,crevice attack, color, and residual corrosion products.15.1.3 The appearance of the test coolant.16. Precision and Bias16.1 PrecisionThe precision of the procedure in this testmethod for measuring corrosion of cast aluminum alloys inengine coolants under heat-rejected condi
42、tions will be deter-mined.16.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.17. Keywords17.1 aluminum; anhydrous; cast aluminum alloys; corro-sion; cylinder head; engine coolant; heat transfer; n
43、on-aqueousAPPENDIX(Nonmandatory Information)X1. INTERPRETATION OF RESULTSX1.1 Generally, unused non-aqueous coolants that producealuminum corrosion rates greater than 1.0 mg/cm2/weekshould be rejected, and non-aqueous coolants that produce lessthan 1.0 mg/cm2/week should be considered as candidates
44、forfurther evaluation. As indicated in 4.2, satisfactory perfor-mance of unused non-aqueous coolants in this test method doesnot ensure adequate long-term service performance, whichshould be established in dynamometer and field service tests.ASTM International takes no position respecting the validi
45、ty of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subjec
46、t to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarte
47、rs. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard
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