ASTM B922

ASTM B922 – Standard Test Method for Metal Powder Specific Surface Area by Physical Adsorption

Description:

Significance and Use

5.1 Both suppliers and users of metals can benefit from knowledge of the surface area of these materials. Results of many intermediate and final processing steps are controlled by, or related to, specific surface area of the metal. The performance of many sintered or cast metal structures may be predicted from the specific surface area of the starting metal powder, or all or a portion of the finished piece.

Scope

1.1 This test method covers determination of surface area of metal powders. The test method specifies general procedures that are applicable to many commercial physical adsorption instruments. The method provides specific sample outgassing procedures for listed materials. It includes additional general outgassing instructions for other metals. The multipoint equation of Brunauer, Emmett, and Teller (BET),2 along with the single point approximation of the BET equation, forms the basis for all calculations.

1.2 This test method does not include all existing procedures appropriate for outgassing metallic materials. The procedures included provided acceptable results for samples analyzed during interlaboratory testing. The investigator shall determine the appropriateness of listed procedures.

1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3.1 State all numerical values in terms of SI units, unless specific instrumentation software reports surface area using alternate units. In this case, present both reported and equivalent SI units in the final written report. Many instruments report surface area as m²/g, instead of using correct SI units (m²/kg).