Page 81 - Handbook of Adhesion Promoters

74 Substrates - Surface Condition and Treat-

Figure 4.23. Schematic illustration of the synthesis and deposition of ZnO nanocrystals on the surface in the
presence of ultrasonic irradiation. The asymmetric collapse near the surface by the generation of microjets as
strong streams results in the particles joining and the formation of the flower-like structure. [Adapted, by permis-
sion, from Sharifalhoseini, Z; Entezari, MH; Jalal, R, Surf. Coat. Technol., 266, 160-6, 2015.]

The adhesion and proliferation of bac-
teria on metallic surfaces in health centers,
industries, and homes increase the risk of
59
human infections. A mild steel was
coated with a Ni-P layer through electroless
59
plating to prevent surface corrosion. To
achieve an antibacterial metallic surface,
simultaneous sono-synthesis and deposi-
tion of ZnO nanoparticles were performed
59
on the Ni-P coating (Figure 4.23). Figure
4.24b shows the presence of peaks attrib-
59
uted to the Ni-P phase. The micrograph
4.24c shows in addition ZnO nanoparticles
which form characteristic needle-like
59
shapes, attached to Ni-P surface. Escheri-
chia coli showed some biological activity
on Ni-P layer but the plate containing ZnO
nanoparticles effectively prohibited the
59
growth of E. coli. This suggests that ZnO
surface could be utilized for antibacterial
59
purposes and reduction of colonization.

Figure 4.24. 3D scanning micrographs. (b) Ni-P coat-
ing, (c) zinc oxide nanoparticles. [Adapted, by permis-
sion, from Sharifalhoseini, Z; Entezari, MH; Jalal, R,
Surf. Coat. Technol., 266, 160-6, 2015.]