Polysiloxane-Multiwalled Carbon Nanotube Layers on Steel Substrate: Microstructural, Structural and Electrochemical Studies

Abstract

The study involved research on two types of nanocomposite coatings based on polysiloxane and multiwalled carbon nanotubes (MWCNTs). The coatings were made using the same steel substrate while they were obtained by two different methods: sequential and co-deposition method. Spectroscopic measurements using Raman and infrared spectroscopy, as well as microscopic examination and wettability tests, were applied to examine structure, microstructure and physical properties of the obtained layers. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) were used to characterize the coatings from the point of view of their corrosion resistance. The Raman confocal spectroscopy provided valuable data explaining the behavior of carbon nanotubes in the polymer matrix and allowed to distinguish structural differences in the two analyzed layers. The results obtained for nanocomposite coatings were compared with the results obtained for coatings made on the basis of their individual components, namely the coating consisting of pure carbon nanotubes as well as those obtained from pure polysiloxane. Based on the applied methods, an attempt to explain the differences in the corrosion resistance of four types of coatings was made.

Corrosion Resistance and Electrical Conductivity of Hybrid Coatings Obtained from Polysiloxane and Carbon Nanotubes by Electrophoretic Co-Deposition

“…The existence of the 2D band, at 2702 cm −1 , which corresponds to the breathing vibrations of six carbons pertaining to a hexagon in the hexagonal carbon lattice confirms the presence of CNT [ 41 ]. The lower spectrum (black one) exhibits additional feature-bands at 490, 2913 and 2971 cm −1 all of which can be attributed to the polysiloxane material [ 37 ]. The first originates from the Si-O vibration, while the other two originate from the C-H stretching vibration in Si-CH 3 [ 37 ].…”

“…The lower spectrum (black one) exhibits additional feature-bands at 490, 2913 and 2971 cm −1 all of which can be attributed to the polysiloxane material [ 37 ]. The first originates from the Si-O vibration, while the other two originate from the C-H stretching vibration in Si-CH 3 [ 37 ]. According to Ferrari and Robertson [ 42 ], in order to determine the structural changes of CNT material and the CNT/PS composite, the I D /I G ratio must be calculated (intensity of D and G bands).…”

“…Electrochemical methods were used to investigate the corrosion resistance of coated titanium samples in Ringer’s solution (8.6 g·dm −3 NaCl, 0.3 g·dm −3 KCl and 0.48 g·dm −3 CaCl 2 ·6H 2 O; Fresenius Kabi, Kutno, Poland) at 37 °C. The experimental setup used for the measurements was described in our previous work [ 37 ]. The potentials were measured with respect to the saturated calomel electrode (SCE).…”

“…These factors are crucial for the final structure, microstructure and other functional properties of the resulting substrate/coating system. In our previous research [ 37 , 38 ], we developed a new method for the production of the coatings using electrophoretic co-deposition. It is based on the application of the suspension prepared in the form of polysiloxane sol with dispersed carbon nanotubes and their simultaneous deposition on the metal electrodes.…”

Surface Properties of Silica–MWCNTs/PDMS Composite Coatings Deposited on Plasma Activated Glass Supports

“…Recently, the use of carbon nanotubes (CNTs) [8] has become more common, and they are now one of the most widely used organic additives due to their unique properties such as small density, excellent mechanical properties, and good thermal and electrical conductivity, which make them an ideal component for the organic phase in composites or hybrids [9][10][11][12]. CNTs are cylindrical structures consisting of rolled-up sheets of single-layer carbon network with the structure (sp 2 ) of graphene [13].…”