FINAL 04 - Micromeritics Flashcards
Science and technology of small particles
Micromeritics
Any unit of matter having defined physical dimensions
Particle
Expressed in diameter
Particle size
An estimate of the size range present and the number or weight fraction of each particle size
Particle size distribution
For particles > 1 μm; use calibrated stage and ocular micrometers
Optical microscopy
Measurement of the distance between tangents parallel to some fixed direction
Feret diameter
Diameter of a circle with the same area as that of the particle observed perpendicular to the surface on which the particle rests
Projected area diameter
Taken as the length of a line that bisects a particle
Martin diameter
Method of choice for classification of the coarser grades of single powders or granules
Sieving
Special cylindrical container designed such that a sample can be removed from the lower portion at selected time intervals
Adreasen apparatus
Coulter counter (Principle involved)
Electronic resistance
HIAV/Royco Light Blockage Instrument (Principle involved)
Light blockage
Beckman Coulter Model (Principle involved)
Photon correlation spectroscopy
Micro-computerized Mercury Porosimetry (Principle involved)
Adsorption
German Counter (Principle involved)
Faraday-Tyndall effect (Light scattering)
Measure of the total voids present in a particle
Porosity
Closest or rhombohedral (Theoretical porosity)
26%
Most open, loosest, or cubic packing (Theoretical porisity)
48%
Ordinary powders (Theoretical porosity)
30-50%
Flocculated powders (Theoretical porosity)
> 48%
Crystalline materials (Theoretical porisity)
<1%
Density exclusive of the voids and intraparticle pores larger than molecular or atomic dimensions in the crystal lattices
True density
Density determined by the displacement of Hg
Granule density
Measure of interparticulate interactions
Bulk density
Achieved by mechanically tapping a measuring cylinder containing a powder sample
Tapped density
Refers to specific bulk volume; reciprocal of bulk density
Bulkiness
Powder flow measurement related to interparticulate friction or resistance to movement between particles
Angle of repose
Generally measured as the mass per time flowing from any of a number of types of containers
Flow through an orfice
Very course particle (Sieve no.)
8
Coarse particle (Sieve no.)
20
Moderately course (Sieve no.)
40
Fine particle (Sieve no.)
60
Very fine particle (Sieve no.)
80