**2.2. Electrochemical codeposition mechanisms**

bath, under constant stirring speed (800 rpm) and using different values of previous stirring time (ranging from 1 to 5 h). Figures 1 to 3 present the surface morphology of the coatings

**Figure 1.** Surface morphology of Cu/γ-Al2O3 coatings produced at -1.20 VSSE from pyrophosphate bath previously stir‐

**Figure 2.** Surface morphology of Cu/γ-Al2O3 coatings produced at -1.20 VSSE from pyrophosphate bath previously stir‐

obtained under these conditions.

160 Electrodeposition of Composite Materials

red for 1 h at 800 rpm [61].

red for 3 h at 800 rpm [61].

The electrochemical codeposition process has been under investigation for several years. Many works have demonstrated the influence of the cations and anions present in the electrolyte and the effects of organic and inorganic additives in the incorporation of the particulate material on the composite coatings. Moreover, as the particulate material should be kept suspended in solution throughout the deposition process, the stirring process is also important for obtaining the MMC coatings [62–67]. Thus, some studies concerning the codeposition mechanism have been carried out trying to propose models that could explain the influence of the deposition parameters on the codeposition phenomenon of inert particles in metallic matrix during the electroplating of a cathodic composite coating [6,8,11,23,24,62–64].

The main problem faced by the authors who proposed such mechanisms was the physical explanation concerning the direct influence of deposition parameters, such as current density, particle concentration in the bath, stirring speed of the suspension, solution pH, and temper‐ ature, for example, on the codeposition phenomenon [38,47,48]. It is a very hard task, and only two models, regarding the codeposition of inert particles, are well accepted [63,64].
