METHOD FOR MEASURING SPECIFIC SURFACE AREA OF POWDER

摘要

The specific surface area of any kind of powder is measured by using the same air-permeability equation irrespective of the particle size. The air permeating times of powder having various porosities measured by a Blaine apparatus by using normal cement lie on a line B-B'. The specific surface area Sb of the normal cement can be expressed by Sb=Kb.f(e).t<1/4>, where Kb=1670/ rho b ( rho b: specific gravity) and f(e)=e<3/2>/(1-e). When Beppu white clay is used as the powder, the graph is a line C-C' and the specific surface area Sc of the white clay can be expressed by Sc=Kc.f<n>(e).t<1/2>. The difference between both specific surface areas Sb and Sc is the index (n) attached to the f(e). Since the index (n) is 1 or other values depending upon the nature and size of the powder, this indicates that the formula of the Sc is not limited to Beppu white clay, but can be applied to any other ordinary powder. When the porosity is 0.57, the value of the f(e) is f(e)=1 and the specific surface area of the powder is the product of the square root of the air permeating time by Kc, namely, 1670/ rho c ( rho c: specific gravity). Therefore, the specific surface area can be measured.