Mono- and multimolecular Langmuir-Blodgett films as protective coatings for friction surfaces

Tribological properties of monomolecular Langmuir-Blodgett films formed from behenic acid, dimethyl octadecylmalonate, 2,4-heneicosanedione, and its copper complex were studied and compared with those of a self-arranged monolayer of octadecyltrichlorosilane. In the micrometer contact range, in friction of a modified silicon surface with a steel ball (indentor), the monomolecular Langmuir-Blodgett films under consideration surpass in the wear resistance the chemisorbed monomolecular octadecyltrichlorosilane film by a factor of 40. The stability of Lamgmuir-Blodgett films in friction correlates with the density of molecular packing on the surface. The friction and wear of Langmuir-Blodgett films are accounted for by the difference in the density of molecular packing of the films under consideration, and also by the transfer of the film substance between the friction surfaces.