抄録
The six methods generally believed to be capable of estimating the flowing ability of a powder, were tested and results obtained were compared with cohesiveness (αc), whose measurement was reported previously. Correlation was recognized between the angle of repose (θp, θd) and αc. The values of ho were obtained by extrapolation of height of the powder cone heap (h) to h axis, using the Train's method. Correlation between ho and αc seemed to exist when αc exceeded 3. There were no relations between packed porosity (εp) and αc, but a correlation was observed between Δε and αc. In the range of αc smaller than 2, all samples were judged as freely drainable and at αc above 3.2, all samples was undrainable. It is concluded that the free flowing of a powder is one of the forms of flowing which can be done only by migration of the surface particle of the bed by gravitational force and, in connection with this, the definition of ability to flow freely is given as easiness to remove the particles sitting on the surface of the loosely packed powder bed. As was defined earlier, cohesiveness (αc) is also the easiness to remove the particles sitting on the surface of the powder bed so that, in the case of the loosely packed powder bed, the ability to flow freely and cohesiveness are different manifestation of the same property of a powder bed.
