1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW14701 Resistance of Coatings to Chemical Etching and Distortion Copyright 2011 General Motors Company All Rights Reserved September 2011 Originating Department: North American Engineering Standards Page 1 of 4 1 Scope Note: Nothing in this standard
2、supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. 1.1 Purpose. This standard describes the test procedures to evaluate the sensitivity of paint coatings or films to etching, distortion or
3、discoloration from exposure to assembly plant chemicals or severe outdoor environmental conditions. 1.2 Foreword. Not applicable. 1.3 Applicability. Not applicable. 1.4 Restricted and Reportable Substances for Parts. All materials supplied to this standard must comply with the requirements listed in
4、 GMW3059, Restricted and Reportable Substances for Parts. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. None 2.2 GM Standards/Specifications. 9985670 9986323 9985809 GMW3059 9986181 GMW16625 3 Resources 3.1 Fac
5、ilities. Not applicable. 3.2 Equipment. 3.2.1 Thermal Gradient Bar, the following model or equivalent: BYK - CHEMIE Model 2612, 250 C, RS232 Computer, 524 S. Cherry, P.O. Box 5670, Wallingford, CT 06492, (203) 265-2086. 3.2.2 Air-circulating electric oven. 3.2.3 Temperature measuring equipment (Data
6、paq system with thermocouples and thermistors or equivalent). 3.2.4 Pipette for application of test materials. 3.2.5 Clean, lint-free, nonabrasive wiping cloths. 3.2.6 Humidity cabinet. 3.3 Test Vehicle/Test Piece. 3.3.1 Test Materials. Unless otherwise indicated in the applicable coating material s
7、pecification, the coating or film shall be exposed to the following materials during basic qualification. Testing of additional materials may be required for specific plant applications. 3.3.2 Environmental Materials. 3.3.2.1 Acid rain mixture per GMW16625 at pH 3 and pH 4. 3.3.2.2 Sulfuric acid sol
8、utions in water 10% by weight and pH of 0 and 2.0. (Adjust per GMW16625). 3.3.2.3 Calcium sulfate solution in water - 0.75% by weight and adjusted to pH of 4.0 with sulfuric acid. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction
9、or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14701 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 2 of 4 3.3.2.4 Deionized water. 3.3.2.5 Egg Albumin 2% by weight in deionized water. Utilize Fisher Scientific Egg Albumin, S
10、oluble Impalpable Powder, and A388-500 or agreed upon equivalent. 3.3.2.6 Fuel Oil Soot 4.0 g sodium metavanadate (NaVO3 H2O), 10.0 g ferrous Sulfate (FeSO4 7H2O) and 8.0 g sulfuric acid the reagents are added to deionized water to give a final volume of 100 mL and a pH value of approximately 1.2. 3
11、.3.2.7 Basic Solution - The preparation of the solution is done by dissolving 4.0 g Sodium Hydroxide, 4.64 g Sodium Phosphate-Dodecahydrate, and 0.33 g Sodium Chloride, in deionized water to make 1 L. This solution has a calculated pH of 13.0. 3.3.3 Plant Materials. 3.3.3.1 Motor Oil, any commercial
12、 5W-30 grade. 3.3.3.2 Windshield Washer Fluid, 9985670 concentrate 1:1 with tap water or commercial mixed materials, full strength. 3.3.3.3 Brake Fluid, 9986323. 3.3.3.4 Poly Alkaline Glycol Oil, 9986181. 3.3.3.5 Engine Coolant, 9985809. The above outlines the typical materials to be tested. Other r
13、egional specific materials may be selected by the responsible engineer. Confirm all materials with the engineer prior to beginning the test method. 3.3.4 Test Panels. Panels shall be prepared using the specified processing such as film build and bake. Recommended panel size is 100 300 mm or larger.
14、For tests with most materials, etching or distortion of the coating surface can be most easily observed on black panels. Where the primary effect is expected to be discoloration, white panels must be used. Because of test variability and rating subjectiveness, control panels of similar current techn
15、ologies should be run concurrent with the coating to be tested. Unless otherwise indicated, coated test panels or film samples shall be aged a maximum of 24 hours at room temperature prior to exposure. 3.4 Test Time. Not applicable. 3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills
16、. Not applicable. 4 Procedure 4.1 Preparation. Not applicable. 4.2 Conditions. Not applicable. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upon. Such requirements shall be specified on component drawi
17、ngs, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Test Procedure. 4.3.1.1 Procedure. Prior to testing, wipe panels with a 50/50 water-isopropyl alcohol (IPA) mixture. For all testing, apply 0.05 mL of the specified test solutions via pipette to the test panel. Multiple solutions can be e
18、valuated on the same panel. Spotted panels are then tested per one or more of the following methods, unless otherwise indicated in the coating material specification. x Method 1 and 2 shall be used for testing of environmental materials (except item 3.3.2.6), and x Methods 2 and 3 for plant material
19、s x Where environmental materials must be evaluated on coated nonmetallic panels not suitable for gradient bar testing, Method 3 may be used at 10 C increments x Method 4 is to be used for environmental materials item 3.3.2.6 only Copyright General Motors Company Provided by IHS under license with G
20、eneral Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW14701 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 3 of 4 4.3.1.1.1 Method 1 Temperature Gradient Bar. 4.3.1.1.1.1 Place drop
21、s along the entire length of two 100 300 mm panels. Drops can be in either a straight line spaced 6.0 mm apart or in a zigzag pattern. 4.3.1.1.1.2 Place panels on gradient bar that runs from 38 to 82 C. Bar should be calibrated to ensure that panel heat up time is no greater than 2 minutes for 0.090
22、 mm thickness steel substrate. Residence time on bar must be adjusted for plastic or thick metal substrates requiring longer heat up times (or use Method 3 at 10 C increments). 4.3.1.1.1.3 Remove one panel after 15 minutes exposure at temperature, and the other panel after 30 minutes exposure. 4.3.1
23、.1.1.4 Rinse any remaining test solution from panels, using water or compatible, nonaggressive solvent. 4.3.1.1.1.5 Record and report etch-free temperature for test coating and control. 4.3.1.1.1.6 Allow panels to recover for 24 hours and re-rate. 4.3.1.1.2 Method 2 Room Temperature Test. 4.3.1.1.2.
24、1 Apply two spots of each test solution to coated panel. 4.3.1.1.2.2 Allow panels to age 24 hours at room temperature. Ambient conditions must be 21 to 25 C, 30 to 50% Relative Humidity (RH) with averages recorded. 4.3.1.1.2.3 Rinse any remaining test solutions from panel using water or applicable s
25、olvent and wipe dry. 4.3.1.1.2.4 Rate and report the affect of each test solution, compared to the control, per the Scale in 5.3.1.1. 4.3.1.1.3 Method 3 Elevated Temperature Test. Follow steps outlined in Method 2 except: 4.3.1.1.3.1 After application of test solutions, place panels in an electric a
26、ir-circulating oven that has been preheated to the specified temperature. Use 70 C, unless otherwise indicated in the applicable coating specification. 4.3.1.1.3.2 Condition panels in oven for 30 minutes at substrate temperature. Record actual substrate temperature. 4.3.1.1.3.3 For testing of enviro
27、nmental materials on nonmetallic substrates which are not suitable for temperature gradient bar, run tests at 50, 60, 70, 80 C, and report etch-free temperature. 4.3.1.1.4 Method 4 Fuel Oil Soot Test. The test piece shall be conditioned for 3 hours in a humidity cabinet at 40 2 C (104 36 F) and 93 2
28、% relative humidity, following which the test medium shall be spotted onto the test surface via pipette in at least 3 places approximately 3 cm apart. Each site wetted with the test solution shall have a diameter of approximately 10 mm. The prepared test piece shall be returned to the humidity cabin
29、et in a horizontal position for 144 hours at 40 2 C (104 36 F) and 93 + 2% relative humidity. After removing from the humidity cabinet, wash the test panel with tap water and air dry. Evaluate per 5.3.1.1 immediately after panel is dried. 5 Data 5.1 Calculations. Not applicable. 5.2 Interpretation o
30、f Results. Not applicable. 5.3 Test Documentation. 5.3.1 Evaluation and Rating. 5.3.1.1 Rating Scale. The subjective rating scale (See Table 1) shall be used to evaluate and report the effect of test materials on the coating or film. In all cases, the effect on controls should be evaluated at the sa
31、me time for comparison. Table 1: Subjective Rating Scale 10 = No Change 8 = Slight 6 = Moderate 4 = Pronounced 2 = Severe Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WO
32、RLDWIDE ENGINEERING STANDARDS GMW14701 Copyright 2011 General Motors Company All Rights Reserved September 2011 Page 4 of 4 5.3.2 Report. 5.3.2.1 The following information must be provided in the report of all test results: 5.3.2.1.1 Complete identification of test coating and control. 5.3.2.1.2 Com
33、plete identification of test solutions. 5.3.2.1.3 Time and verified temperature for each test. 5.3.2.1.4 For Method 1, etch-free temperature and comparison to control. 5.3.2.1.5 For Methods 2 and 3, rating of effect and comparison to control. 6 Safety This standard may involve hazardous materials, o
34、perations, 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 7 No
35、tes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbreviations, and Symbols. IPA Isopropyl Alcohol RH Relative Humidity 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW14701 9 Release and Revisions This standard was originated in October 20
36、05. It was first approved by the Global Paint Team in September 2006. It was first published in December 2006. Issue Publication Date Description (Organization) 1 DEC 2006 Initial publication. 2 SEP 2011 5 Year Refresh. (Primer, Topcoat and Color Global Tech Team - GPPC) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
