1、Standard Method of Test for Mass Weight of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings AASHTO Designation: T 65M/T 65-13 ASTM Designation: A90/A90M-11 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C.
2、20001 TS-4h T 65M/T 65-1 AASHTO Standard Method of Test for Mass Weight of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings AASHTO Designation: T 65M/T 65-131ASTM Designation: A90/A90M-11 1. SCOPE 1.1. This test method covers procedures for determining the mass weight of coating o
3、n iron or steel sheet, wire, and other articles in which the coating is zinc or a zinc alloy, such as zinc-5 percent aluminum (including zinc-5 percent aluminum-mischmetal and zinc-5 percent aluminum-0.1 percent magnesium) or 55 percent aluminum-zinc. In the body of this test method, reference to zi
4、nc coating shall be interpreted to also include zinc-alloy coating except where specifically stated otherwise. 1.2. The final results determined by this test method shall be expressed in SI units or inch-pound units, depending on the units used in the material specification to which the results are
5、to be compared. Certain portions of the procedure involving determination of specimen mass weight traditionally have been performed in SI units, and corresponding inch-pound units are not included. 1.3. For sheet products, the final results are expressed as either coating mass weight total both side
6、s, or coating mass weight separately on each side, depending on the specified requirements. 1.4. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health pra
7、ctices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see Section 5.1. 1.5. Current regulation codes and hazard classifications for chemicals used in this test method are listed in R 16. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: R 16, Reg
8、ulatory Information for Chemicals Used in AASHTO Tests 2.2. ASTM Standards: A653/A653M, Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process A792/A792M, Standard Specification for Steel Sheet, 55% Aluminum-Zinc Alloy-Coated
9、by the Hot-Dip Process A875/A875M, Standard Specification for Steel Sheet, Zinc-5% Aluminum Alloy-Coated by the Hot-Dip Process A1046/A1046M, Standard Specification for Steel Sheet, Zinc-Aluminum-Magnesium Alloy-Coated by the Hot-Dip Process 2015 by the American Association of State Highway and Tran
10、sportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 65M/T 65-2 AASHTO A1063/A1063M, Standard Specification for Steel Sheet, Twin-Roll Cast, Zinc-Coated (Galvanized) by the Hot-Dip Process D1193, Standard Specification for Reagent Water E29, Standard Practic
11、e for Using Significant Digits in Test Data to Determine Conformance with Specifications 3. SIGNIFICANCE AND USE 3.1. This test method provides a standard method for determining the mass weight of coating for comparison with specification requirements. A coating of zinc on iron or steel articles pro
12、vides protection against corrosion. As the protection is provided by sacrificial loss of zinc, the degree of protection is proportional to the mass weight of zinc coating. Specifications for zinc-coated articles frequently provide for different classes of coating so that the purchaser can select the
13、 coating mass weight most suitable to his needs. 4. REAGENTS 4.1. Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical So
14、ciety, where such specifications are available.2Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 4.2. Purity of WaterWater used to prepare chemical solutions shall be reag
15、ent water as defined by Type IV of ASTM D1193. 4.3. Antimony Trichloride SolutionDissolve 20 g of Sb2O3or 32 g of SbCl3in 1000 mL of HCl (sp gr 1.18 to 1.19). 4.4. Hydrochloric Acid (sp gr 1.18 to 1.19)Concentrated hydrochloric acid (HCl). 4.5. Hydrochloric AcidAntimony Trichloride SolutionAdd 5 mL
16、of antimony trichloride solution to 100 mL of HCl (sp gr 1.18 to 1.19). 4.6. Hydrochloric Acid (1+1)Mix 500 mL of HCl (sp gr 1.18 to 1.19) with 500 mL of reagent water and cool to room temperature. 4.7. Sulfuric Acid (25+75)Mix 250 mL of H2SO4(sp gr 1.84) with 750 mL of reagent water and cool to roo
17、m temperature. Note 1It is advisable to use an inhibitor with acid solution (for example, hexamethylamine tetramine or similar) at the concentration level according to the manufacturers recommendations to prevent attack of the substrate. 5. HAZARDS 5.1. WarningSmall amounts of the poisonous gas stib
18、ine (SbH3) may be evolved during the stripping process using the hydrochloric acid-antimony trichloride method. Hydrochloric acid fumes are present, and hydrogen gas is evolved in the stripping process. Therefore, the test should be performed under conditions of adequate ventilation. A fume hood is
19、recommended for large numbers of samples or where the test is to be carried out frequently over extended periods of time. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 65M/T 65-3 AASHTO 5.2. Wa
20、rningMixing of sulfuric acid with water could result in severe injuries if not properly done. Mixing must be done by slowly adding sulfuric acid to water due to the heat generated and possible splashing. Under no circumstances should the water be added to the acid. The mixing should be performed und
21、er an acid fume hood. 6. SAMPLING 6.1. Zinc-Coated SheetsSamples for mass weight-of-coating determination shall be secured in accordance with ASTM A653/A653M, A792/A792M, A875/A875M, A1046/A1046M, or A1063/A1063M depending on the type of coating. Note 2For convenience in calculating test results in
22、SI units, the specimen should have an area of 3330 mm2of sheet (57.7 0.1 mm square or 65.1 0.1 mm in diameter). For results to be reported in inch-pound units, the specimen should have an area of 5.08 in.2of sheet (2.25 0.01 in. square or 2.54 0.01 in. in diameter). The mass weight of coating in gra
23、ms on a specimen of that area is numerically equal to the mass weight of coating in ounces per square foot of sheet. 6.2. Zinc-Coated WireSamples shall be secured as designated in the appropriate specification. The specimen of wire may be of any length greater than 305 mm 12 in., but preferably abou
24、t 610 mm 24 in. Where a continuous length is not available, shorter lengths totaling more than 305 mm 12 in., but preferably about 610 mm 24 in., shall be used. Because the density of the steel is known to be 7830 kg/m3or 0.283 lb/in.3, it is not necessary to use a specific length of specimen. 6.3.
25、Zinc-Coated Articles Other Than Sheet or WireSamples for mass weight of coating determination shall be secured as designated in the appropriate specification. Except as otherwise provided, the specimens should have a minimum area of 2000 mm23 in.2 of zinc-coated surface. For very small items, severa
26、l pieces may have to be stripped to obtain the minimum area. 6.3.1. In the case of threaded articles, such as bolts and screws, the determination shall be made on a portion of the articles that does not include any thread. 7. PROCEDURE 7.1. Strip the zinc coating from the specimens by using one of t
27、he following methods: hydrochloric acid (1+1), hydrochloric acid-antimony trichloride solution, or sulfuric acid (2+75). For zinc alloy coatings containing less than 90 percent zinc, the stripping shall be done using hydrochloric acid (1+1) or sulfuric acid (25+75). 7.2. Clean the specimens by washi
28、ng with solvent naphtha or other suitable solvent, then rinse with alcohol and dry thoroughly. 7.3. Determine the mass weight of the specimens individually to the nearest 0.01 g, except for articles other than sheet or wire with a specimen mass weight greater than 125 g. For articles other than shee
29、t or wire with a specimen mass weight greater than 125 g, determine the mass (weight) to at least the nearest 0.1 g. After determining the mass weight, immerse each specimen singly in the stripping solution and allow to remain until the violent evolution of hydrogen has ceased and only a few bubbles
30、 are being evolved. This requires about 15 to 30 s, except in the case of sherardized coatings, which require a somewhat longer time. The same solution may be used repeatedly until the time required for stripping becomes inconveniently long. The temperature of the stripping solution shall at no time
31、 exceed 38C 100F. After stripping, wash the specimens by scrubbing them under running water, dip in hot water, and wipe or blow dry. Determine the mass weight of the specimens again, to the same precision as in the initial determination. 2015 by the American Association of State Highway and Transpor
32、tation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 65M/T 65-4 AASHTO 7.4. Sheet SpecimensWhen measuring the total coating mass weight on both sides, or the single side coating mass weight on each side, determine the area of sheet (one surface) to the nearest 5
33、 mm20.01 in.2. If specimens were prepared to the dimensions as provided in Note 2, they shall be presumed to have an area of 3330 mm25.08 in.2. When it is not possible to determine the area accurately, as in specimens from corrugated sheets, the thickness of the stripped sheet shall be determined to
34、 the nearest 0.01 mm 0.001 in. 7.4.1. When determining the coating mass weight on one side of sheet material, use the procedure described in Section 7.3, except use a “stop-off” to protect one side from the stripping medium. Acid-resistant paints or lacquers, acid-resistant tape, or mechanical devic
35、es fastened to the test specimen are examples of commonly used “stop-off” materials. Apply the “stop-off” to the specimen after the initial determination of mass weight, and remove before the second determination of mass weight. Because of the possibility of moisture absorption during the stripping
36、process, the “stop-off” must not be on the specimen during either mass weight determination. Determine the coating mass weight on the second side subsequently without a “stop-off” on the first side. 7.5. Wire SpecimensDetermine the diameter of the stripped wire to the nearest 0.01 mm 0.001 in. by ta
37、king the average of two measurements at right angles to each other. 7.6. Specimens Other Than Sheet or WireDetermine the total coated area of the original specimen to the nearest 5 mm20.01 in.2. Alternatively, for specimens of uniform thickness of base metal, such as a piece of plate or pipe, determ
38、ine the average thickness of the stripped specimen to the nearest 0.01 mm 0.001 in. 8. CALCULATION 8.1. Zinc-Coated Sheet: 8.1.1. Results in SI Units: 8.1.1.1. When the area of sheet is determined, calculate the mass of coating as follows: ( )12=C WW A K (1) where: C = mass of coating, g/m2of sheet;
39、 W1= original mass of specimen, g; W2= mass of stripped specimen, g; A = area of one surface of the sheet in mm2(or in.2); and K = a constant = 1 106when A is in mm2, or = 1.55 103when A is in in.2Note 3If the specimen was prepared to the dimensions as provided in Note 2, having an area of 3330 mm2o
40、f sheet, the factor K/A is approximately 300, which may be used in the calculation. 8.1.1.2. When it is not possible to obtain a specimen of measurable area, calculate the mass of coating as follows: ( )122C WWW T K= (2) where: C = mass of coating, g/m2of sheet; W1= original mass of the specimen, g;
41、 W2= mass of stripped specimen, g; 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 65M/T 65-5 AASHTO T = thickness of stripped sheet, mm (or in.); and K = a constant = 7.83 103when T is in mm, or
42、 = 1.99 105when T is in in. 8.1.2. Results in Inch-Pound Units: 8.1.2.1. When the area of one surface of the sheet is determined, calculate the weight of coating as follows: ( )12C WW A K=(3) where: C = weight of coating, oz/ft2of sheet; W1= original weight of specimen, g; W2= weight of stripped spe
43、cimen, g; A = area of one surface of the sheet, mm2 (or in.2); and K = a constant = 3.28 103when A is in mm2, or = 5.08 when A is in in.2Note 4If the specimen was prepared to the dimensions as provided in Note 2, having an area of 5.08 in.2, the loss of weight in grams is numerically equal to the we
44、ight of coating in ounces per square foot of sheet. 8.1.2.2. When it is not possible to secure a specimen of measurable area, calculate the weight of coating as follows: ( )122C WWW T K= (4) where: C = weight of coating, oz/ft2of sheet; W1= original weight of specimen, g; W2= weight of stripped spec
45、imen, g; T = thickness of stripped sheet, mm (or in.); and K = a constant = 25.7 when T is in mm, or = 652 when T is in in. 8.2. Zinc-Coated Wire: 8.2.1. Results in SI Units: 8.2.1.1. Calculate the mass of zinc coating as follows: ( )122C WWW D M= (5) where: C = mass of coating, g/m2of stripped wire
46、 surface; W1= original mass of specimen, g; W2= mass of stripped specimen, g; D = diameter of stripped wire, mm (or in.); and M = a constant = 1.96 103when D is in mm, or = 4.97 104when D is in in. 8.2.2. Results in Inch-Pound Units: 8.2.2.1. Calculate the weight of zinc coating as follows: ( )122C
47、WWW D M= (6) 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 65M/T 65-6 AASHTO where: C = weight of coating, oz/ft2of stripped wire surface; W1= original weight of specimen, g; W2= weight of stri
48、pped specimen, g; D = diameter of stripped wire, mm (or in.); and M = a constant = 6.42 when D is in mm, or = 163 when D is in in. 8.3. Zinc-Coated Articles Other Than Sheet or Wire: 8.3.1. Results in SI Units: 8.3.1.1. Calculate the mass of zinc coating as follows: ( )12C WW A N=(7) where: C = mass
49、 of coating, g/m2of surface; W1= original mass of specimen, g; W2= mass of stripped specimen, g; A = coated area of original specimen, mm2(or in.2); and N = a constant = 1 106when A is in mm2, or = 1.55 103when A is in in.2 8.3.1.2. If the specimen has a uniform thickness of base metal, calculate the mass of coating as follows: ( )122C WWW G Z= (8) where: C = mass of coating, g/m2, of
