1、Standard Method of Test for Mass Weight of Coating on Aluminum-Coated Iron or Steel Articles AASHTO Designation: T 213M/T 213-11 (2015)1ASTM Designation: A428/A428M-10 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 T
2、S-4h T 213M/T 213-1 AASHTO Standard Method of Test for Mass Weight of Coating on Aluminum- Coated Iron or Steel Articles AASHTO Designation: T 213M/T 213-11 (2015)1ASTM Designation: A428/A428M-10 1. SCOPE 1.1. This test method covers procedures for determining the mass weight of coating on aluminum-
3、coated iron or steel sheets and wire, and on other aluminum-coated iron and steel articles. 1.2. The final results determined by this test method shall be expressed in SI or inch-pound units, depending on the units used in the material specification to which the results are to be compared. Certain p
4、ortions 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 sides, or coating mass weight
5、 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 practices and determine the
6、applicability of regulatory limitations prior to use. For a specific precautionary statement, see Note 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, Regulatory Information for
7、 Chemicals Used in AASHTO Tests 2.2. ASTM Standards: D1193, Standard Specification for Reagent Water E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications E177, Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods E691
8、, Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 3. SIGNIFICANCE AND USE 3.1. This test method provides a standard method of determining the mass weight of coating for comparison with specification requirements. A coating of aluminum on iron or
9、steel articles 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4h T 213M/T 213-2 AASHTO provides protection against corrosion by forming a relatively inert barrier. Specifications for aluminum-coated
10、articles occasionally provide for different masses weights of coating so that the purchaser can select the coating mass weight most suited to his needs. The heavier coating will provide greater protection against mechanical damage, which may break the coating. 4. REAGENTS 4.1. Purity of ReagentsReag
11、ent 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 Society, where such specifications are available.2Other grades may be used, provided it is
12、 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 in preparation of reagent solutions shall conform to ASTM D1193, Type IV or better. 4.3. Antimony Trichloride SolutionDissolve 200
13、g of antimony trichloride (SbCl3) in 1000 mL of concentrated hydrochloric acid (HCl, sp gr 1.18 to 1.19) without heating. 4.4. Hydrochloric Acid (sp gr 1.18 to 1.19)Concentrated hydrochloric acid (HCl). 4.5. Sodium Hydroxide Solution(20 percent). Dissolve 20 parts by mass weight of sodium hydroxide
14、(NaOH) in 80 parts of water. 4.6. Stannous Chloride SolutionDissolve 100 g of stannous chloride (SnCl22H2O) in 1000 mL of concentrated hydrochloric acid (HCl, sp gr 1.18 to 1.19) without heating. Add a few granules of reagent-grade tin. 4.7. Hydrochloric Acid (1+1)Mix 500 mL of HCl (sp gr 1.18 to 1.
15、19) with 500 mL of reagent water and cool to room temperature. Note 1Warning: Small amounts of the poisonous gas stibine (SbH3) may be evolved during the stripping process using the hydrochloric acidantimony trichloridestannous chloride method. Hydrochloric acid fumes are present, and hydrogen gas i
16、s evolved in the stripping process. Therefore, the test should be performed under conditions of adequate ventilation. A fume hood is recommended for large numbers of samples or where the test is to be carried out frequently over extended periods of time. 5. SAMPLING 5.1. Aluminum-Coated SheetsSample
17、s for mass-of-coating weight-of-coating determination shall be secured as designated in the appropriate specification. Test specimens shall have a minimum area of 2000 mm23 in.2 of sheet, but preferably approximately 3300 mm25 in.2 of sheet. Note 2For results to be reported in SI units, the specimen
18、 should have an area of 3300 mm2of sheet (57.7 0.1-mm square or 65.1 0.1 mm in diameter). For convenience in calculating test results 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 grams on
19、 a specimen of that area is numerically equal to the mass weight of coating in ounces per square foot of sheet. 5.2. Aluminum-Coated WireSamples shall be secured as designated in the appropriate specification. The specimen of aluminum-coated wire may be of any length greater than 300 mm approximatel
20、y 12 in., but preferably about 600 mm approximately 24 in. Where a continuous length is not available, shorter lengths totaling more than 300 mm, but preferably about 600 mm, shall be used. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplicatio
21、n is a violation of applicable law.TS-4h T 213M/T 213-3 AASHTO Because the density of the steel is known (7830 kg/m3or 0.283 lb/in.3), it is not necessary to use a specific length of specimen 5.3. Aluminum-Coated Articles Other Than Sheet or WireSamples for mass weight of coating determination shall
22、 be secured as designated in the appropriate specification. Except as otherwise provided, the specimens should have a minimum area of 1935 mm23 in.2 of aluminum-coated surface. For very small items, several pieces may have to be stripped to obtain the minimum area. 5.3.1. In the case of threaded art
23、icles, such as bolts and screws, the determination shall be made on a portion of the article that does not include any thread. 6. PROCEDURE 6.1. Strip the aluminum coating from the specimens by using one of the following methods the sodium hydroxidehydrochloric acid method (Method A), the hydrochlor
24、ic acidantimony trichloridestannous chloride method (Method B), or the dilute hydrochloric acid method (Method C). Note 3Methods A and B are the most common methods used for sheets. 6.2. Clean the specimens immediately before determining the mass weight by washing in petroleum ether or other suitabl
25、e solvent, and dry thoroughly. 6.3. Determine the mass weight of the specimens individually to the nearest 0.01 g. 6.4. Sodium Hydroxide-Hydrochloric Acid Method (Method A)Heat the NaOH solution to approximately 90C 195F (Note 4) and immerse each specimen in the hot solution until the strong reactio
26、n ceases. With silicon-free coatings, evolution of gas for considerable time is likely, but do not leave the specimens in the solution for more than a few minutes. Longer immersion inhibits the removal of coating during subsequent dips. Immersion of several specimens simultaneously is permitted, pro
27、vided all surfaces are freely exposed to the solution. Remove specimens from solution and scrub all surfaces under running tap water with a clean cellulose sponge to remove the loose deposit formed in the NaOH solution. Use vigorous scrubbing as necessary for some types of coating, but do not use ab
28、rasive materials to remove the deposit. Blot with a towel to remove most of the water (Note 5) and immerse each specimen singly for not more than 3 s in HCl (sp gr 1.18 to 1.19) at room temperature. Remove, scrub again under running tap water with a sponge, and reimmerse in the hot NaOH solution for
29、 not more than a few minutes or until action again ceases. Repeat this cycle until immersion in HCl shows no visible reaction (Note 6). Use one to three or more cycles as required, depending on the type and weight of coating. After the final immersion in the NaOH and HCl solutions, scrub as before,
30、dry thoroughly, and determine the mass weight of each specimen to the nearest 0.01 g. Note 4The temperature is not critical, but the solution should be held several degrees below the boiling point (approximately 105C) to prevent excessive foaming during the first immersion. The beaker used for heati
31、ng the solution and immersing the specimens should be less than half full of solution to avoid the danger of foaming over when the specimens are immersed. Note 5Most of the water should be removed to prevent dilution of the HCl, as dilute HCl will attack the base metal to a greater extent than conce
32、ntrated HCl. Note 6It is sometimes difficult to determine the point at which all of the alloy layer has been removed when stripping silicon-free coatings. If in doubt, determine the mass weight of the specimen (after scrubbing and drying) and then put it through one additional stripping cycle. Loss
33、in mass weight due to the additional cycle will be on the order of 0.005 g on a 57.2-mm 2.25-in. square sheet specimen, if all the coating had been removed before the extra cycle. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a vio
34、lation of applicable law.TS-4h T 213M/T 213-4 AASHTO 6.5. Hydrochloric Acid-Antimony Trichloride-Stannous Chloride Method (Method B)After determining the mass weight, immerse each specimen singly in a solution made by mixing 100 mL of antimony trichloride solution and 100 mL of stannous chloride sol
35、ution (Note 7). Allow the specimen to remain immersed until the evolution of hydrogen has ceased. Action will stop after 1 to 4 min, or somewhat longer, depending on the thickness and silicon content of the coating. Use fresh solution for each test (Note 8). The temperature of the stripping solution
36、 shall not exceed 38C 100F. After stripping, wash the specimen and scrub it with a soft cloth, using a small amount of abrasive cleansing powder if necessary. Rinse the specimens and dry thoroughly with an absorbent cloth or paper and determine the mass weight of each specimen to the nearest 0.01 g.
37、 Note 7Mix the antimony trichloride and stannous chloride solutions together as needed. Note 8Very heavy coatings may show residual coating after all action has stopped. If, on examination after stripping, any coating still remains, repeat the immersion step using fresh solution. 6.6. Dilute Hydroch
38、loric Acid Method (1+1) (Method C)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 are being evolved. Action will stop after 1 to 4 min or somewhat longer depending
39、on the thickness and silicon content of the coating. Use of the same solution is permitted until the time for stripping becomes inconveniently long. The temperature of the stripping solution shall at no time exceed 38C 100F. After stripping, wash the specimens by scrubbing them under running water,
40、dip in hot water and wipe or blow dry. Determine the mass weight of each specimen to the nearest 0.01 g. 6.7. 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 mm
41、20.01 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, determine the average thickness of the stripped sheets to the
42、 nearest 0.01 mm 0.001 in. 6.7.1. When determining the single-side coating mass weight of sheet material, use the procedures described in Sections 6.4, 6.5, or 6.6, except use a “stop-off” to protect the second side from the stripping medium. Acid-resistant paints or lacquers, acid-resistant tape, o
43、r mechanical devices fastened to the test specimen are examples of commonly used “stop-off” materials. Apply the “stop-off” to the specimen after the first determination of mass weight and remove before the second determination of mass weight. Because of the possibility of moisture absorption during
44、 the stripping 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. 6.8. Wire SpecimensDetermine the diameter of the stripped wire to the nearest 0.01 mm
45、0.001 in. by taking the average of two measurements at right angles to each other. 6.9. 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
46、or pipe, determine the average thickness of the stripped specimen to the nearest 0.01 mm 0.001 in. 7. CALCULATION 7.1. Aluminum-Coated Sheet: 7.1.1. Results in SI Units: 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of
47、applicable law.TS-4h T 213M/T 213-5 AASHTO 7.1.1.1. When the area of one surface of the sheet is determined, calculate the mass weight of aluminum coating as follows: ( )12C WW A K=(1) where: C = mass of coating, g/m2of sheet; W1= original mass of specimen, g; W2= mass of stripped specimen, g; A = a
48、rea 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 9If the specimen was prepared to the dimensions as provided in Note 2, having an area of 3330 mm2of sheet, the factor K/A is approximately 300, which may be used in the cal
49、culation. 7.1.1.2. When it is not possible to obtain a specimen of measurable area, calculate the mass of the coating as follows: ( )122C WWW T K= (2) where: C = mass of coating, g/m2of sheet; W1= original mass of the specimen, g; W2= mass of the stripped specimen, g; T = thickness of stripped sheet, mm (or in.); and K = a constant = 7.83 103when T is in mm, or = 1.99 105when T is in in. 7.1.2. Results in Inch-Poun
