Samples placed in an adsorbate gas atmosphere will undergo physical adsorption on the surface of the substance (the surface of the particles and the internal through holes) at low temperature. When the adsorption gas reaches equilibrium, the equilibrium adsorption pressure and the amount of adsorbed gas are measured. According to the BET equation, the monomolecular layer adsorption amount of the sample to be measured can be obtained, thereby calculating the specific surface area of ​​the sample. This standard stipulates the method for measuring the specific surface area of ​​solid substances based on the BET principle of gas adsorption. It is suitable for the determination of the specific surface area of ​​powders and porous materials (including nano-powders and nano-scale porous materials), and its measurement range is 0.001 ～ 1000㎡ / g. Measuring methods include volumetric specific surface area analysis test, gravimetric specific surface area analysis test and gas chromatography specific surface area analysis test. Nitrogen is generally used as the adsorption gas, but krypton gas can be used for samples with a positive surface area. Before the measurement, the sample needs to be degassed, which is especially important for nanomaterials. The material adsorbed on the sample surface can be removed by degassing, but the irreversible change of the surface should be avoided.
The standard is non-equivalent to adopt IS09277: 1995 Determination of the specific surface are La of solids by gas adsorpti On using the BET method.
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