ASTM C1274-12(R2020) pdf free download

ASTM C1274-12(R2020) pdf free download.Standard Test Method for Advanced Ceramic Specific Surface Area by Physical Adsorption
1. Scope
1.1 This test method covers the determination of the surface area of advanced ceramic materials (in a solid form) based on multilayer physisorption of gas in accordance with the method of Brunauer, Emmett, and Teller (BET) (1) 2 and based on IUPAC Recommendations (1984 and 1994) (2, 3). This test method specifies general procedures that are applicable to many commercial physical adsorption instruments. This test method provides specific sample outgassing procedures for selected common ceramic materials, including: amorphous and crystalline silicas, TiO 2 , kaolin, silicon nitride, silicon carbide, zirconium oxide, etc. The multipoint BET (1) equation along with the single-point approximation of the BET equation are the basis for all calculations. This test method is appropriate for measuring surface areas ofadvanced ceramic powders down to at least 0.05 m 2 (if in addition to nitrogen, krypton at 77.35 K is utilized as an adsorptive). 1.2 This test method does not include all existing proce- dures appropriate for outgassing of advanced ceramic materi- als. However, it provides a comprehensive summary of proce- dures recommended in the literature for selected types of ceramic materials. The investigator shall determine the appro- priateness of listed procedures. 1.3 The values stated in SI units are to be regarded as standard. State all numerical values in terms of SI units unless specific instrumentation software reports surface area using alternate units. In this case, provide both reported and equiva- lent SI units in the final written report. It is commonly accepted and customary (in physical adsorption and related fields) to report the (specific) surface area of solids as m 2 /g and, as a convention, many instruments (as well as certificates of refer- ence materials) report surface area as m 2 g –1 , instead of using SI units (m 2 kg –1 ). 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 An appropriately sized (to provide at least the minimum surface area required for reliable results, refer to requirements provided by the manufacturer of the instrument or apparatus being used) aliquot of sample is outgassed under appropriate conditions prior to analysis. For details on outgassing methods and examples of specific outgassing conditions recommended for selected ceramic materials, see Section 11. 4.2 The adsorptive gas is admitted to a sample container held at a constant temperature. The amounts adsorbed are measured in equilibrium with the adsorptive gas pressure, p, and plotted against the relative pressure, p/p 0 (where p 0 is the saturation vapor pressure), to give an adsorption isotherm. Adsorption isotherms may be obtained by volumetric (mano- metric) measurements or by the carrier gas flow measurements (flow volumetric method) and gravimetric techniques. This test method employs volumetric and flow volumetric methods. 4.3 (Multipoint BET Analyses Only)—The volume of gas adsorbed, or desorbed, is determined for a minimum of four relative pressures within the linear BET transformation range of the physical adsorption, or desorption, isotherm character- istic of the advanced ceramic. The linear range is that which results in a least-square correlation coefficient of 0.995 (pref- erably 0.999) or greater for the linear relationship (see linear form of BET equation, in Annex A1). Typically, the linear range includes relative pressures between 0.05 and 0.30 (4, 5). However, microporous materials usually require use of a range of lower relative pressures (often a linear BET range can be found in the relative pressure range from 0.01 to 0.1 (5, 6)). For details, see Annex A2.