1、BRITISH STANDARD BS 5117-2.6: 1992 Testing corrosion inhibiting, engine coolant concentrate (“antifreeze”) Part 2: Methods of test for corrosion inhibition performance Section 2.6 Test for corrosion of cast aluminium alloys under heat-transfer conditions NOTEIt is recommended that this Section be re
2、ad in conjunction with the information given in the “General introduction” published separately as BS5117-0.BS5117-2.6:1992 This British Standard, having been prepared under the directionof the Chemicals Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into
3、 effect on 1May1992 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference CIC/7 Draft for comment91/50973 DC ISBN 0 580 20760 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Chemicals Standar
4、ds Policy Committee (CIC/-) to Technical Committee CIC/7, upon which the following bodies were represented: BCIRA British Chemical Distributors and Traders Association Limited British Railways Board British Telecommunications plc Chemical Industries Association Consumer Policy Committee of BSI Depar
5、tment of Trade and Industry (National Physical Laboratory) Institute of Petroleum Ministry of Defence Royal Automobile Club Society of Motor Manufacturers and Traders Limited Amendments issued since publication Amd. No. Date CommentsBS5117-2.6:1992 BSI 09-1999 i Contents Page Committees responsible
6、Inside front cover Foreword ii 0 Introduction 1 1 Scope 1 2 Principle 1 3 Reagents and materials 1 4 Apparatus 1 5 Metal test specimen 2 6 Sampling of the product and preparation of the test solution 3 7 Preparation of the test specimen 3 8 Procedure 4 9 Cleaning of the test specimen 4 10 Expression
7、 of results 5 11 Test report 5 Figure 1 Heat-transfer corrosion test assembly 2 Figure 2 Heat-transfer corrosion test components 3 Publication(s) referred to Inside back coverBS5117-2.6:1992 ii BSI 09-1999 Foreword This Section of BS5117 has been prepared under the direction of the Chemicals Standar
8、ds Policy Committee. It is based upon ASTM D4340-89 “Test method for corrosion of cast aluminium alloys in engine coolants under heat-transfer conditions” 1) , published by the American Society for Testing and Materials. Modifications to the ASTM standard have been made, particularly with respect to
9、 cleaning of the test specimen and the interpretation of results. It is envisaged that BS6580 will be revised to refer to this Section of BS5117 as well as other Sections of BS5117, each of which contains a test method to be used in determining compliance with BS6580. This Section describes a method
10、 of test only and should not be used or quoted as a specification defining limits of performance. Reference to this Section should indicate that the method of test used is in accordance with BS5117-2.6. At the time of publication of this British Standard, no corresponding International Standard exis
11、ts. WARNING. This Section of BS5117 describes a method that involves the use of hazardous materials, equipment and operations. This method should be carried out only by appropriately qualified personnel and attention is drawn to the relevant Health and Safety provisions. A British Standard does not
12、purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside fro
13、nt cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) Copies may be obtained from the ASTM European Office,27
14、-29 Knoll Piece, Wilbury Way, Hitchin, Herts, SG4 OSX, England.BS5117-2.6:1992 BSI 09-1999 1 0 Introduction It is essential that engine coolants prevent corrosion of aluminium cylinder heads under heat-transfer conditions during engine operation. Any corrosion products formed could deposit on the in
15、terior surfaces of the radiator and overheating and boil-over of the cooling system could then occur. The test method described provides a means for selectively screening unused engine coolants and will readily distinguish those coolants that are unsuitable for use with aluminium cylinder head engin
16、es. However, satisfactory performance of a coolant in this test does not ensure adequate long-term service performance. Additional, more comprehensive evaluations with simulated service, dynamometer and vehicle tests should be used to establish the long-term effectiveness of the coolant. 1 Scope Thi
17、s Section of BS5117 describes a method, suitable for laboratory use, for evaluating the effectiveness of engine coolants in combating corrosion of aluminium casting alloys under heat-transfer conditions that may be present in aluminium cylinder head engines. NOTE 1The engine coolant concentrate is r
18、eferred to hereafter as “the product”. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle A heat flux is established through a test specimen of cast aluminium alloy typical of that used for engine cylinder heads while exposed to the pro
19、duct under a pressure of193kPa. The temperature of the aluminium specimen is maintained at135 C and the test is continued for1 week(168h). The effectiveness of the product for preventing corrosion of the aluminium under heat-transfer conditions (hereafter referred to as heat-transfer corrosion) is e
20、valuated on the basis of the change in mass of the test specimen. 3 Reagents and materials 3.1 General. The reagents used shall be of a recognized analytical grade. Except where otherwise stated, water complying with grade3 of BS3978 shall be used throughout. 3.2 Sodium chloride 3.3 Acetone 3.4 Comp
21、ressed air 3.5 Mild detergent 3.6 Cleaning solution. The cleaning solution shall be prepared as follows. Dissolve10g of chromium(VI) oxide in450ml of water and25ml of orthophosphoric acid. Make the aqueous solution up to500ml with water. WARNING. Chromium(VI) oxide is a strong oxidant. Ensure that i
22、t does not come into contact with skin, eyes and clothing, and do not breathe the dust. Orthophosphoric acid is a strong acid. Ensure that it does not come into contact with skin or eyes. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Heat-transfer corrosion cell NOTE 1The assembled corrosion cel
23、l is shown schematically in Figure 1. It is assembled from components, some of which require glass blowing or machining. The glass O-ring cell shall be constructed from two glass O-ring joints joined to an additional middle section of glass tubing of the same diameter to make a total length of530mm.
24、 NOTE 2It is necessary for high strength glass with a low coefficient of expansion to be used for the O-ring cell. Heat resistant O-rings shall be used. NOTE 3Polytetrafluoroethylene is not suitable for the O-rings, because of a high creep rate at the test temperature. Internal pressure shall be mon
25、itored using a suitable pressure gauge, and a pressure relief valve shall be installed to protect against bursting. The top assembly plate (as shown in Figure 2), shall be constructed of stainless steel, and the heat-transfer bar and bottom assembly plate (also illustrated inFigure 2) shall be const
26、ructed of stainless steel or mild steel. NOTE 4Stainless steel is preferred for the heat-transfer bar and bottom assembly plate. The complete assembly shall incorporate a thermal cut-off device. 4.3 Temperature controller, with high temperature alarm and temperature control range up to at least150 C
27、, with a tolerance of 1 C. A Type J thermocouple shall be used (see BS4937-3). A heavy duty electrical power relay of30A rating or a suitable solid state contactor shall be connected to the temperature controller to carry the current load to the band heater(4.4). NOTEThe relay, if used, should be ch
28、anged after about every50000 cycles to prevent contact welding. 4.4 Band heater, at least950W, of inside diameter approximately50mm and length approximately125mm. 4.5 Ultrasonic cleaner, about50W. 4.6 Vacuum oven, with temperature range up to about150 C, fitted with a thermal cut-off device, for ove
29、n temperature protection.BS5117-2.6:1992 2 BSI 09-1999 4.7 Clear plastics safety shield 4.8 Desiccator 4.9 Analytical balance, capable of weighing to the nearest0.1mg. 4.10 Precision potentiometer 4.11 Scraper, of thick polyethylene or polypropylene with freshly sheared edge, or of other material so
30、fter than aluminium. 4.12 Fume hood 4.13 Microscope, with magnification range 10to 30. 4.14 pH meter 5 Metal test specimen A cast test specimen, formed from aluminium alloy of designation LM4 complying with BS1490, of diameter65mm and thickness13mm shall be used. The location of the thermocouple hol
31、es shall be as is illustrated in Figure 2. Figure 1 Heat-transfer corrosion test assemblyBS5117-2.6:1992 BSI 09-1999 3 6 Sampling of the product and preparation of the test solution 6.1 Sampling The product shall have been sampled as described in clause2 of BS5117-2.1:1985. 6.2 Preparation of the te
32、st solution Dissolve165mg of the sodium chloride(3.2) in750ml of water, and then add250ml of the product. NOTEThis is sufficient solution for two tests. 7 Preparation of the test specimen 7.1 Polish the test specimen (see clause5) successively with coarse, medium and fine grit emery cloth or paper,
33、and finally with P1200 2)waterproof silicon carbide paper. Figure 2 Heat-transfer corrosion test components 2) The “P” series of abrasive grades is described in the Grain size standard for coated abrasives, FEPA43-GB-1984, published by the Federation of European Producers of Abrasive Products,20 Ave
34、nue Reille,75014 Paris.BS5117-2.6:1992 4 BSI 09-1999 7.2 Wash the test specimen with warm tap water and then rinse with distilled or deionized water, and finally with the acetone(3.3). Ensure that the thermocouple holes are free from metal chips and polishing debris. Flush the holes with the acetone
35、 and remove excess liquid using a glass capillary pipette or other suitable means. 7.3 Dry the test specimen in the vacuum oven(4.6) for a minimum of4h at65 C to90 C to remove residual liquid that may be retained in a porous casting. From this point onwards, use thin cotton gloves or a suitable equi
36、valent when handling the specimen in order to avoid weighing errors. 7.4 Remove the specimen from the oven and allow it to cool to room temperature in the desiccator(4.8). 7.5 Weigh the specimen to the nearest0.1mg using the balance(4.9) and record the mass. The test specimen may be re-used, if desi
37、red, but shall be prepared in accordance with this clause prior to re-use. 8 Procedure 8.1 Assemble the heat-transfer corrosion cell(4.2) as shown in Figure 1. Use new O-rings between the aluminium test specimen and corrosion cell for each test. To help ensure that the O-rings are properly seated, a
38、pply a small amount of the test solution to the glass O-ring groove for lubrication. Avoid overtightening of the threaded rod nuts. 8.2 Transfer into the corrosion cell sufficient volume of the test solution (see6.2) to ensure that there is25ml of the test solution per square centimetre of exposed a
39、luminium surface, screw the plug into the hole and tighten it. Place the safety shield(4.7) around the cell, pressurize the cell to138kPa with the compressed air(3.4), and turn on the band heater(4.4). Ensure that provision is made for a pressure rise with increase in temperature. Adjust the pressur
40、e gradually so that when the temperature reaches the specified test temperature the final pressure is193kPa. WARNING. Despite the presence of a safety relief valve, test cells have burst under pressure. Use of a safety shield is therefore essential. A clear plastics enclosure, having allowance for a
41、dequate circulation of air, yet completely surrounding the test apparatus, has been successfully used for this purpose. 8.3 Adjust the temperature of the aluminium test specimen to135 1 C using the temperature controller(4.3). Monitor the temperature at the auxiliary thermocouple hole at periodic in
42、tervals with the precision potentiometer(4.10). Operate the cell continuously at this temperature for1week(168h). 8.4 At the end of the test period, turn off the heater and allow the cell to cool to room temperature before disassembly. Release the pressure, remove the fill plug, and pour or siphon o
43、ut the test solution. Record the appearance and final pH of the test solution using the pH meter(4.14). 8.5 Clean and weigh the aluminium test specimen as described in clause9. NOTEAfter disassembly, the corrosion cell should be cleaned with a large bristle brush rotated by a motor, e.g.an electric
44、drill motor, using pumice powder, the mild detergent(3.5) and water. If deposits are not removed by this procedure, the cell should be immersed in chromic acid cleaning solution until clean, and carefully rinsed. 8.6 Repeat the procedure described in8.1 to8.5 at least twice more. 9 Cleaning of the t
45、est specimen 9.1 Wash the specimen with a soft bristle brush using the mild detergent(3.5). Remove any O-ring residue by gentle use of the scraper(4.11). 9.2 In the fume hood(4.12), immerse the specimen for exactly5min in the cleaning solution(3.6), maintained at approximately80 C. Occasionally brus
46、h the surface with a soft bristle brush. After5min, transfer the beaker containing the test specimen and cleaning solution to the ultrasonic cleaner(4.5) and clean for1min. 9.3 Remove the test specimen from the cleaning solution, flush well with tap water, then with distilled or deionized water, and
47、 finally with the acetone(3.3). Make sure that the thermocouple holes are flushed well and that excess liquid is removed. Inspect the surface using the microscope(4.13). If any deposits remain, repeat the procedure described in9.2 and9.3. 9.4 Dry the specimen in the vacuum oven(4.6) using the same p
48、rocedure and precautions as describedin7.3. 9.5 Cool the specimen to room temperature in the desiccator(4.8), weigh it to the nearest0.1mg and record the mass. 9.6 Determine the average loss in mass resulting from cleaning three uncorroded specimens as described in9.1 to9.5. Use the average loss in
49、mass as a blank correction, provided that the deviations are within the repeatability given in10.2.BS5117-2.6:1992 BSI 09-1999 5 10 Expression of results 10.1 Calculation The heat-transfer corrosion rate (R) (expressed inmg/cm 2 week), is given by the following expression: where M bis the mass of the test specimen before the test (in g); M ais the mass of the test specimen after the test (in g); B is the loss in mass of the blank (in g); A is the heat-flux surface area inside the O-ring (in cm 2 ). 10.2 Precision Repeatability and reproducibility of
