Значение и использование

These test methods for the chemical analysis of zinc-nickel alloy coating on sheet steel are primarily intended as referee methods to test such materials for compliance with compositional specifications such as found in Specification A 918, particularly those under the jurisdiction of ASTM Committee A05 on Metallic-Coated Iron and Steel Products. It is assumed that all who use these test methods will be trained analysts capable of performing common laboratory procedures skillfully and safely. It is expected that work will be performed in a properly equipped laboratory under appropriate quality control practices such as those described in Guide E 882.

These test methods must be applied twice, once to each side of the specimen if coating weight and composition are required for both sides of a coated sheet. Two separate specimens are required for this purpose.

Область применения

1.1 These test methods cover independently the chemical analysis of each surface of zinc-nickel alloy electrolytically coated on steel sheet. The coatings have chemical compositions within the following limits:

AnalyteConcentration RangeCoating Weight0.0 to 80 g/m²Nickel7.0 to 17.0 %

1.2 These test methods are in the following sections:

SectionsCoating Weight, by the Weigh-Strip-Weigh Method (20.0 to 45.0 g/m²)Nickel by the Atomic Absorption Method (11.0 to 13.5 % of Coating Weight Ranging from 20 to 45 g/m²)

1.3 The values stated in SI units are to be regarded as standard. In some cases, exceptions allowed in Practice E 380 are also used.

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 applicability of regulatory limitations prior to use.

1.4 This test method provides a procedure for determining independently the weight of coating on each surface of zinc-nickel alloy-coated sheet steel, in coating masses from 20 to 45 g/m² (Note 0).

Note 0

The upper limit of the scope has been set at 45 g/m² because test materials with higher coating weight were not available for testing in accordance with Practice E 173. However, recognizing the simplicity of the weigh-strip-weigh technique, materials with higher coating weights can be tested following this procedure. Users of this test method are cautioned that use of it for coating weight determinations above 45 g/m ² is not supported by interlaboratory testing.

1.5 This test method covers the determination of nickel in concentrations from 11.0 to 13.5 % in zinc-nickel coatings ().

Note 2

The upper limit of the scope has been set at 13.5 % because sufficient test materials containing higher nickel were unavailable in accordance with Practice E 173. However, recognizing the calibration technique of atomic absorption spectrophotometer, materials with higher nickel content may be tested following this procedure. Users of this test method are cautioned that use of it for nickel determination out of the scope is not supported by the interlaboratory testing.