The effects of TiO2 sol concentration on single- and multiple-scratch damage in electroplated Ni–B-TiO2 sol composite coating

Anticorrosion properties of silica-based sol-gel coatings on steel – The influence of hydrolysis and condensation conditions

“…Additionally, it is believed that temperature treatment above 100 °C promotes the formation of covalent bonds over the formation of hydrogen bonds [48], so covalent bonding mainly determines the scratch resistance properties of the obtained coatings. based on organic solvents with longer hydrocarbon chains, such as propanol and butanol, and aprotic acetone, a decrease in tangential force is observed, which suggests that coatings based on these solvents are characterized by better lubricant properties that favor the sliding between the tip and the coating materials [50]. This seems to be confirmed by the evolution of the friction coefficient during the test (Fig.…”

“…For the analyzed coatings, the damage observed in the coatings may initiate from decohesion between the coating and the P265GH steel substrate, observed as spallation at the first step of the test, and then followed by adhesion damage, such as is observed by the delamination of the coatings in the middle of the scratches. These results, along with the fact that all surfaces before coating were treated in the same way, suggest that, in the cases analyzed, changes in the structure of the coating materials and the elastic-plastic stress related to these have a significant influence on critical forces operating within the coating layers [48,50]. It should also be noted that the friction coefficient slowly increases during the increase in the normal force applied during the scratch test.…”

“…Due to the high value of the observed permanent deformation of the residual scratch track around 13 µm, and the value of the plastic factor around 1.0, it is concluded that the coatings are characterized by plastic deformation that is accompanied by very low elastic recovery [50]. All analyzed samples were characterized by a decrease in EOCP during the initial exposure to 0.5 M NaCl.…”

“…Changes within oxide matrix structure can have a significant influence on the scratch resistance of the coatings, as mentioned above. The sol-gel coatings based on siloxanes bond to the metallic substrate by interfacial bonding, based on hydrogen bonding, condensation reactions, and covalent bonding with hydroxyl groups localized on the surface of the steel substrate [48,50,51]. Furthermore, the mechanism of bonding of sol-gel materials to the metallic surface is usually explained by the conversion of hydrogen bonding via covalent condensation, which is promoted by thermal treatment of the coatings after their application [20].…”

“…11 e). The Pf value describes the degree of plastic deformation of the coatings, and is calculated from the ratio of Rd to Pd, according to equations 2-3 [50]:…”