The apparent density of tungsten powder and its measuring method

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The apparent density of tungsten powder

The apparent density of tungsten powder refers to the bulk density that is measured when tungsten powder freely fills in the standard container under specific condition, which is the unit volume mass of tungsten powder when it is loose filled, of which the unit is g/cm3. Besides, it belongs to one of processing properties of powder. Tungsten apparent density is the integrated embodiment of powder performances, which is important to the stable processing and quality control of tungsten powder as well as the basis of mold design.

There are many factors that can influence the apparent density of tungsten metal powder, such as the particle shape, size, surface roughness, size distribution of tungsten powder and so on. Usually, these factors will vary a lot according to different manufacturing methods and processing conditions of tungsten powder. Generally speaking, the apparent density of powder will decrease with the decrease of particle size, the enlargement of particle non spherical coefficient and the increase of surface roughness.

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The measuring methods of tungsten powder apparent density

Tungsten powder apparent density is the integrated embodiment of tungsten powder performances, which has very important effects on the manufacturing technique and quality control of tungsten powder. There are many methods that can be used to measure the apparent density of tungsten powder, below are the instructions to the three main measuring methods of tungsten powder: funnel method, Scott volumeter method and oscillating funnel method.

a. Funnel method: tungsten powder falls freely from a certain height of funnel hole and fill in the cup, in which the powder apparent density is measured by the mass of unit volume powder under loose state.

b. Scott volumeter method: put tungsten powder in the screen of upside combined funnel, which will flow into the cloth box freely or by using the external force, afterwards, it will alternately pass four glass panes and rectangular funnels that have the slant angle of 25° in the cloth box, eventually, it will fall freely from a certain height of funnel hole and fill in the cylindrical cup and appears to be loose state. Thus the powder density in the cylindrical cup can be measured.

c. Oscillating funnel method: put tungsten powder in the funnel that has rapping device and vibrate it under certain conditions, afterwards, the powder will fall freely from the funnel hole in a certain height and fill in the cup, thus the powder density can be measured.

Funnel method can be applied in measuring the apparent density of powders that can flow freely under specified conditions; while the latter two methods are applied in the non-free flowing powders.