Specific surface area of ​​nano-powder materials and its measuring instrument - Database & Sql Blog Articles

The specific surface area is the surface area per unit mass of material (m2/g), which is one of the most important physical properties of ultrafine powder materials, especially nano-powder materials. It is used to evaluate their activity, adsorption, catalysis and Other properties. Important physical properties. Therefore, it is very important to determine the specific surface area of ​​various ultrafine powder materials during their research, manufacture and application. With the rapid development of ultra-fine powder materials and nano-materials, the production and application of various fields of almost all powder materials such as ultra-micro zinc oxide, aluminum oxide, calcium carbonate, lithium cobaltate, lithium manganate, carbon black, graphite, etc. The specific surface area of ​​the product needs to be determined. The instrument for measuring the specific surface area has become an indispensable important equipment for many research institutes, universities and factories.
There are many methods for determining the specific surface area, such as Densichron Examination, CTAB, and Electromicroscopic Examination; Tint trength ), Nitrogen Surface Area, etc. EM Nelson considers low temperature nitrogen adsorption as the most reliable, effective, and classic method by various methods. ASTM and international ISO have been included in the test standards (D3037 and ISO-4650). China has also listed this method as a national standard (GB-10517). In 2003, it also included the testing standards for nano-powder materials.
The nitrogen adsorption specific surface meter is developed on the basis of the principle of gas chromatography. It uses nitrogen as the adsorbate and helium or hydrogen as the carrier gas. The two gases are mixed in a certain ratio to achieve the specified relative pressure, and then flow through the powder material sample. When the sample tube is filled with liquid nitrogen (-196) °C) When the cup is heated, the powder material physically adsorbs nitrogen in the mixture, and the carrier gas is not adsorbed. An adsorption peak appears at the chromatographic workstation (gas sensor system). When the powder sample is returned to room temperature when the liquid nitrogen cup is removed, the adsorbed nitrogen is desorbed, and a desorption peak opposite to the adsorption peak appears on the workstation. The size of the adsorption peak or the desorption peak is proportional to the amount of nitrogen adsorbed on the surface of the sample, and is also considered to be proportional to the surface area of ​​the powder sample. Take a standard sample, such as a powder material of known specific surface area, or a pure volume of known volume, to obtain a standard peak in the workstation. By comparing the standard peak with the peak area of ​​the sample to be tested, it can be finally obtained. Specific surface area.