THE IMPORTANCE OF AIR CONTENT ON THE

ABSTRACT：The air that is usually present between the particles of a powder mass can vary considerably in quantity depending on how the powder is handled or processed. Powders are complex because their flow properties are dependent upon many factors of which air content is one of the most important. This is a study of the relationship between air content and powder rheology using the FT4 Powder Rheometer. The principle of measuring the energy required to set up given flow patterns in a powder sample is used to characterise the powders. A range of materials will be reviewed in relation to how their flow properties are changed by consolidation at one extreme and aeration at the other. Over this range, it will be shown that the energy required to produce flow varies typically in the range of 10-100 for most powders. For many free-flowing and fluidisable materials, this ratio could be more than 1000. The propensity of a powder to release its entrained air is also important because of the consequential change of rheological properties. De-aeration behaviour is investigated as part of this study. 挤出机X-trude 1400