**3.2. Particle charging**

The charge on the particles can be developed according to the following mechanisms:


Charged particle in a suspension is surrounded by oppositely charged ions. In the so-called boundary layer, the concentration of these ions is higher than their concentration in the bulk electrolyte. These ions and the particle should move in opposite directions when an electric field is applied. At the same time, the ions are also attracted by the particle, and as a result, a fraction of the ions surrounding the particle will not move in the opposite direction but move along with the particle. Accordingly, the speed of a particle is not determined by the surface charge but by the net charge enclosed in the liquid sphere, which moves along with the particle [6, 29]**.**

#### **3.3. Particle transport**

The particle transfer toward the cathode surface occurs by four mechanisms, namely convec‐ tion, migration, diffusion, and Brownian movement.

Convection: It includes thermal and stirring effects, which can be increased extensively by applying vibration, shock, and other stirring types and temperature gradients.

Migration: It is the movement of positive ions and negative ions, or charged particles, through the electrolyte under the effect of applied potential between the electrodes immersed in that electrolyte. The migration process occurs only for charged particles.

Diffusion: Electrode reaction decreases the concentration of oxidant or reductant at the electrode surface, producing a concentration gradient. Thus, the species movement from the higher to the lower concentration is enhanced. The diffusion process occurs for both charged and uncharged particles.

Brownian's movement: It is dependent on the particle size and may be ignored for particle size larger than 1 μm [24].

#### **3.4. Other interparticle forces**

During the electrodeposition process of nanocomposites, the following forces are taken into consideration:

