ASTM A90/A90M-21 pdf free download.Standard Test Method for Weight [Mass] of Coating on lron and Steel Articles with Zinc or Zinc-Alloy Coatings.
1.1 This test method covers procedures for determining the weight [mass] of coating on iron or steel sheet, wire, and other articles in which the coating is zinc or a zinc alloy, such as zinc-5 % aluminum (including zinc-5 % aluminummischmeial and zinc-5 % aluminum-O. 1 % magnesium), zincaluminum-magnesium (including zinc-5 to 9 % aluminuminagnesium and zinc—9 to 1 3 % aluminum—magnesium) or 55 %.
protection against corrosion. As the protection is provided by sacrificial loss of zinc, the degree of protection is proportional to the weight [mass] of zinc coating. Specifications for zinc- coated articles frequently provide for different designations or classes of coating so that the purchaser can select the coating weight jmassl most suitable for the intended application.
3.2 This test method determines the average coating weight [mass] over a specified area, from which the average thickness can be calculated. Other test methods not described herein can determine the thickness directly at point locations on the coating; in such cases, the required test method is described in that material specification or by reference to another appropriate test method standard.
4. Reagents
4.1 Purity of Reagents—Reagent 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.3 Other 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 Waler—Water used to prepare chemical solutions shall he reagent water as defined by Type IV of Specification D1193.
4.3 Antimony Trichioride Solution—Dissolve 20 g of Sb2o3 or 32 g of SbC11 in 1000 mL of HCl (sp gr 1.18 to 1.19).
4.4 Hydrochloric Acid (sp gr 1. 18 to 1. 19)—Concentratcd hydrochloric acid (HCl).
4.5 Hydrochloric Acid—A ntiinony Trich to ride Solution— Add 5 mL of antimony trichioride solution to 1(X) mL of HC1 (sp gr 1.18 to 1.19).
4.6 Hydrochloric Acid (1 + 1)—Mix 500 mL of HCI (sp gr 1.18 to 1.19) with 500 mL of reagent water and cool to room temperature.ASTM A90/A90M pdf download.