1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW16625 Preparation of Acid Rain Solution Copyright 2011 General Motors Company All Rights Reserved August 2011 Originating Department: North American Engineering Standards Page 1 of 3 1 Scope Note: Nothing in this standard supercedes applicable laws
2、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 covers the procedure for making the acid rain solution used in GMW14701, Resistance of Coatings to Chemical Etching and Distortion. 1.2 Fo
3、reword. Not applicable. 1.3 Applicability. Not applicable. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM D1193 2.2 GM Standards/Specifications. GMW14701 2.3 Additional References. None. 3 Resources 3.1 Fac
4、ilities. Not applicable. 3.2 Equipment. 3.2.1 Balance capable of measuring to 0.01 g. 3.2.2 Volumetric flasks, 300 ml and 1000 ml. 3.2.3 Ice bath. 3.2.4 Standardized pH meter. 3.3 Test Vehicle/Test Piece. Not applicable. 3.4 Test Time. Not applicable. 3.5 Materials. 3.5.1 Concentrated sulfuric acid,
5、 95 to 98% concentration. All acids shall be reagent grade. 3.5.2 Concentrated nitric acid, 70 to 72% concentration. All acids shall be reagent grade. 3.5.3 Concentrated hydrochloric acid, 35 to 40% concentration. All acids shall be reagent grade. 3.5.4 Degassed, distilled, deionized water (ASTM D11
6、93, Type IV). 3.6 Formulas. 3.6.1 The 1 N acid stock solution should be 0.62 N sulfuric acid (H2SO4); 0.32 N nitric acid (HNO3); 0.06 N hydrochloric acid (HCl). See Table 1 for acid characteristics. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for Res
7、aleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16625 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 2 of 3 Table 1: Acid Characteristics Name Molecular Weight (g/mole) Equivalent Weight (g/equivalent) Concentr
8、ation Range % Sulfuric Acid 98 49 95 to 98 Nitric Acid 63 63 70 to 72 Hydrochloric Acid 36.5 36.5 35 to 40 3.6.2 Calculation of Weight of Concentrated Acid for Mixture (g). 3.7 Test Required Information. Not applicable. 3.8 Personnel/Skills. Not applicable. 4 Procedure for Preparation of a 1 N Acid
9、Stock Solution 4.1 Preparation. 4.1.1 To 300 mL of degassed, distilled, deionized water in a 1000 mL volumetric flask, slowly add the specified grams of sulfuric acid. In order to minimize heating, the volumetric flask should be surrounded by ice (ice bath). The flask should be swirled during the ad
10、dition. 4.1.2 Allow the contents to cool. 4.1.3 Follow paragraphs 4.1.1 and 4.1.2 for the nitric acid and hydrochloric acid. 4.1.4 Add the distilled water to within 50 mL of the mark. Remove the flask from the ice bath and allow the contents to return to room temperature. Dilute to volume. This make
11、s a solution of approximately pH 0. 4.1.5 Obtain higher pH solutions by standard dilution of this stock solution. The final pH can be adjusted to exactly the desired value with either 2 N HCl or 1 N NaOH (Sodium Hydroxide). Table 2 shows sample dilutions: Table 2: Sample Dilutions Starting pH mL of
12、Starting pH Final Volume Final pH 0 10 100 1 0 10 1000 2 2 10 100 3 2 10 1000 4 3 10 100 4 4.1.6 Verify that the pH is properly adjusted on a calibrated pH meter. 4.2 Conditions. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard
13、shall have been agreed upon. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. Not applicable. 5 Data 5.1 Calculations. Not applicable. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for Resal
14、eNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16625 Copyright 2011 General Motors Company All Rights Reserved August 2011 Page 3 of 3 5.2 Interpretation of Results. Not applicable. 5.3 Test Documentation. Not applicable. 6 Safety This sta
15、ndard 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 appropriate safety and health practices and determine the applicability of r
16、egulatory limitations prior to use. 7 Notes 7.1 Glossary. g Gram HCl Hydrochloric Acid HNO3 Nitric Acid H2SO4 Sulfuric Acid N Normal NaOH Sodium Hydroxide 7.2 Acronyms, Abbreviations, and Symbols. Not applicable. 8 Coding System This standard shall be referenced in other documents, drawings, etc., a
17、s follows: Test to GMW16625 9 Release and Revisions This standard was originated in May 2011. It was first approved by the Primer, Color & Topcoat Global Tech Team in August 2011. It was first published in August 2011. Issue Publication Date Description (Organization) 1 AUG 2011 Initial publication. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
