Solids 3 & 4

Micrometrics

the science of small particles

Interparticle void

the spaces between particles

Intraparticle void

the spaces within an individual particle

Porosity

the voids in a collection of particles

Porosity calculation

porosity (ε) = (Vb-V)/Vb

Bulk density

ratio of the mass of powder to the total volume of untapped powder

What is the inverse of bulk density?

bulkiness

Bulk density calculation

⍴b = m/Vb

What is the relationship between porosity and bulk density?

inverse

Sieve analysis

performed using a nest of sieves where each lower sieve has a smaller aperture size than that of the sieve above it

Calculation for sieves

sieve number * [(aperture size)+(wire diameter)] = 25,400 μm = 1 in

How are sieve number and aperture size related?

inversely

What effect does a smaller particle size have on interactions between particles?

increases interactions

What effect does a smaller particle size have on mixing?

decreases

Determinants of sedimentation rate

particle diameter, density, gravity, viscosity

Light scattering

occurs when a focused beam of light encounters a particle; the scattering reveals the size of the particle

What relationship does light scattering have to particle size?

The smaller the particle, the greater the scattering angle of light