1、 ENGINEERING STANDARDS Test Procedure SUPERCEDED EDS-T-7761 Determination of the Resistance of Automotive Components to Sulphur Dioxide in a High Humidity Environment This standard may be applied only for current projects. It is Superceded for all future projects and replaced by GMW14728. Copyright
2、2011 General Motors Company All Rights Reserved October 2011 Originating Department: GM Korea Engineering Standards Page 1 of 4 Version : 3 1 Scope Note: Nothing in this standard supersedes applicable laws and regulations. Note: In the event of conflict between the Korean and English language, the K
3、orean language shall take precedence. 1.1 Purpose. The purpose of this test method is to determine the resistance of metals, metallic and other protective coatings, normally applied to automotive components to sulphur dioxide in an environment of high humidity. 1.2 Applicability. The test is acceler
4、ated and carried out using sulphur dioxide injected into air saturated with water vapor at specified temperatures. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. DIN 50018 ISO 3231 2.2 GM Standards/Specification
5、s. EDS-M-1101 2.3 Additional References. None 3 Resources 3.1 Equipment. 3.1.1 The apparatus required for this test procedure shall consist of:- a test cabinet having a reservoir capable of being heated, test piece supports, pressure balance valves, gas supply pipe and necessary means of control. 3.
6、1.2 Test apparatus to DIN 50 018 or ISO 3231 - 1974 is suitable for this test procedure. 3.1.3 The test apparatus shall be installed preferably in a corrosive free environment having temperature and humidity conditions of +23 E 5K and 75 % maximum relative humidity. The apparatus shall be shielded f
7、rom draughts and local sources of heat. 3.1.4 Test Cabinet. The test cabinet shall have a minimum capacity of 300 litres and be air-tight. The walls of the cabinet shall be made from corrosion resistant material of low thermal conductivity. Materials of construction shall be such that they do not in
8、fluence the corrosion resistance of test pieces. The cabinet shall have a heated reservoir situated in the floor area which shall be sufficient capacity to meet the specified operating parameters. Suitable devices (e.g. thermostat and thermometer) shall be provided to control and record temperatures
9、. The temperature shall be measured adjacent to test pieces. All valves and gas pipe fittings shall be positioned above the water level. The ceiling of the cabinet shall be designed so that droplets of condensation shall not be permitted to fall on test pieces. 3.1.5 Reservoir. The reservoir shall b
10、e filled with distilled or deionized water the volume of which shall be 0.67 % of the test cabinet capacity (equivalent to 2 liters of water/300 liter capacity cabinet). The test cabinet shall be emptied and cleaned after each cycle. Fresh deionized / distilled water shall be used for each cycle. GM
11、 KOREA ENGINEERING STANDARDS EDS-T-7761 Copyright 2011 General Motors Company All Rights Reserved October 2011 Page 2 of 4 Version : 3 3.1.6 Test Racks. The test racks shall be made from corrosion resistant material or shall be covered by a corrosion resistant coating. The corrosion resistance of te
12、st pieces shall not be influenced by materials of construction. Materials used as suspension devices for test racks shall be made from inert electrically non-conductive substances e.g. glass. 3.1.7 Gas Supply. Sulphur dioxide shall be supplied from steel cylinders to the test cabinet via. appropriat
13、e pipework. Suitable equipment shall be installed to monitor the exact volume of gas consumed. Alternatively it is permissible to generate sulphur-dioxide in situ. e.g. sodium bisulphite and dilute sulphuric acid. 3.2 Test Piece. 3.2.1 Test Piece Preparation. 3.2.1.1 Where possible tests shall be co
14、nducted on complete components. The test can also be conducted on specially prepared test panels of a minimum area 250 cm. 3.2.1.2 Where the size and/or shape of the component prohibits testing of the complete component, test pieces shall be cut from the component. Such test pieces shall have the la
15、rgest possible size and shall be cut such that the edges are not heavily mechanically deformed nor subjected to excessive temperatures. All cut edges shall be protected in a suitable manner (e.g. with adhesive tapes, protective paints etc.) during test. 3.2.1.3 Any selective portion of a test piece
16、not requiring to be tested shall be suitably protected with a material which does not affect, or be affected by the test medium. 3.2.1.4 For initial sample approval and arbitration purposes at least 3 test pieces, and for routine quality control at least 1 test piece shall be tested. 3.2.2 Cleaning
17、of Test Pieces. 3.2.2.1 Metallic and metal coated test pieces shall be degreased and cleaned using a non chlorinated solvent (e.g. Xylene of Petroleum Spirit). For soft coatings such as tin terne, care must be exercised to avoid smearing the terne layer. The cleaning shall be carried out immediately
18、 prior to testing. 3.2.2.2 Anodised aluminium test pieces shall be cleaned with acid free dichloromethane prior to testing. 3.2.2.3 Test pieces with protective coatings other than those defined in clauses 3.2.2.1 and 3.2.2.2 shall not be cleaned prior to testing. 4 Procedures 4.1 Calibration of Test
19、 Apparatus. 4.1.1 The apparatus shall be checked for correct functioning in designated timer periods by measuring the corrosive effect of exposure to sulphur dioxide on 5 test panels of dimensions (501001) mm and 2 blanking steel panels (2504001) mm made from sheet steel to SPCC (EDS-M-1101). 4.1.2
20、Test panels prior to test shall be thoroughly cleaned using suitable solvent (e.g. xylene or petroleum spirit). 4.1.3 Test panels shall be weighed to the nearest 1mg. 4.1.4 Test panels shall be positioned vertically in the test cabinet with the blanking panels arranged vertically on either side. 4.1
21、.5 Test panels shall receive 120 hours (5 cycles) exposure under a sulphur dioxide concentration of 2.0 liters. 4.1.6 At the end of the test period the panels shall be removed from the test cabinet. The corrosion products removed by immersing in inhibited hydrochloric acid at +23 E 5K and dried afte
22、r rinsing in deionized / distilled water. y Inhibited Hydrochloric Acid: Either a solution of 230 ml HCl (SG 1.18) in 730 ml distilled or deionized water to which has been added 0.1 % Iso-propyl alcohol or a solution of 40 g SbCL3 per liter HCl (SG 1.19). 4.1.7 The test panels shall be re-weighed to
23、 the nearest 1 mg. 4.1.8 The weight loss shall be . . . . . . . . g/m2. 4.2 Conditions. 4.2.1 Environmental Conditions. 4.2.1.1 One cycle consisting of two parts shall be of 24 hours duration. The first part shall be 8h and at the commencement of this part sulphur dioxide shall be introduced into th
24、e test cabinet and the heating applied such that the cabinet stabilities to 40 E 3K within a time period of 1.5 hours. The second part of the cycle shall GM KOREA ENGINEERING STANDARDS EDS-T-7761 Copyright 2011 General Motors Company All Rights Reserved October 2011 Page 3 of 4 Version : 3 be 16h an
25、d commences with switching off the heat appliance and venting the test cabinet to atmosphere. The cabinet shall cool to +23 E 5K within a period of 1.5 hours. 4.2.1.2 The material to be tested shall determine the sulphur dioxide concentration. 4.2.1.2.1 The following test periods shall be used. Code
26、 Test Period ( ) minutes A Specially defined B 24 C 48 D 72 E 96 F 120 G 144 4.2.1.2.2 The test pieces shall be exposed to one of the following sulphur dioxide concentrations. Code Volume of Sulphur Dioxide (in liters) per 300 liters of test chamber capacity 1 2.0 2 1.0 3 0.2 4.2.2 Test Conditions.
27、Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc 4.3 Instructions. The test apparatus shall be prepared for use following which test pieces shall be positioned within the test ar
28、ea such that they are not permitted to touch one another and no droplets of condensation shall fall from one test piece to another. To ensure comparable conditions of exposure, total test piece surface area shall as far as possible be kept constant for each test. The following minimum spacing shall
29、be observed: y Distance from the walls: 100mm. y Distance of the bottom edge of test piece from the water level: 200mm. y Distance between test pieces: 20mm. After sealing of the test cabinet and instruction of sulphur dioxide as specified, the heating appliance shall be switched on and the temperat
30、ure raised to +40 E 3K within approximately 1.5 hours and maintained for a total period of 8 hours from the commencement of the test cycle. At the end of this period, the heating appliance shall be switched off and the test cabinet vented to atmosphere. After a further 16 hours the test pieces shall
31、 be removed for interim examination. The test pieces shall be replaced, the reservoir emptied, cleaned if necessary and then refilled with the specified volume of water. The test cabinet shall be sealed, injected with sulphur dioxide and with the reapplication of heat the second cycle commences. On
32、completing the specified test period, the test pieces shall be removed from the cabinet and unless otherwise stated, washed with distilled / deionized water and allowed to dry at +23 E 5K and evaluated. 5 Data 5.1 Evaluations. Visual evaluation of the test pieces or components shall be carried out i
33、mmediately after the specified test period (see clause 4.2.1.2.1) and appropriate grading allocated according to the following criteria. 5.1.1 Grade 1. No change of surface. 5.1.2 Grade 2. Change of surface appearance allowed but no corrosion of the base material. 5.1.3 Grade 3. Specially defined. 5
34、.2 Expression of Results. The test pieces or components shall be evaluated against the requirements of the relevant engineering drawings or material specifications and reported with reference to this test method. GM KOREA ENGINEERING STANDARDS EDS-T-7761 Copyright 2011 General Motors Company All Rig
35、hts Reserved October 2011 Page 4 of 4 Version : 3 6 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropria
36、te safety and health practices and determine the applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbreviations, and Symbols. Not applicable. 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Hum
37、idity/Sulphur Dioxide Testing to EDS-T-7761 - B 1 - Grade 1 Requirement (clause 5.1) Sulphur Dioxide Concentration (clause 4.2.1.2.2) Test Period (clause 4.2.1.2.1) Test Method Designation 9 Release and Revisions This standard was originated in April 2004. It was first approved by Engineering Standard Committee in April 2004. It was first published in April 2004. Issue / P9I8)Y Publication Date / 38 88 Description (Organization) / 9PP9I76 (:04.2P ) 3 OCT 2011 Apply new Engineering Standard Template. Superceded (Polymer / Organic Material Lab Team) / 4 d3TE:4 64 957 . F9I957 =* (G)8*4G D4 )
