Particle aggregation in materials science

Materials science

Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...

 is direct mutual attraction

Attraction

In general, an attraction draws one object towards another one. The term may have the following specific meanings.* In physics, attraction may refer to gravity or to the electromagnetic force* Attractiveness...

 between particles (atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s or molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

s) via van der Waals force

Van der Waals force

In physical chemistry, the van der Waals force , named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral...

s or chemical bonding.

Particle aggregation is often spontaneous

Spontaneous

Spontaneous* Spontaneous abortion* Spontaneous bacterial peritonitis* Spontaneous combustion* Spontaneous emission* Spontaneous fission* Spontaneous generation* Spontaneous human combustion* Spontaneous Music Ensemble* Spontaneous order...

 and involves one particle attaching to another particle or existing aggregate of particles.

Particle aggregation occurs when particles come into close contact with each other.

When there are collisions between particles in fluid, there is a chance that particles will attach to each other and become larger particle.

There are 3 major physical mechanisms to form aggregate: Brownian motion

Brownian motion

Brownian motion or pedesis is the presumably random drifting of particles suspended in a fluid or the mathematical model used to describe such random movements, which is often called a particle theory.The mathematical model of Brownian motion has several real-world applications...

; Fluid shear; and differential settling.