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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Towards superlubricity in nanostructured surfaces: the role of van der Waals forces

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Autor(es):
Echeverrigaray, Fernando G. [1] ; de Mello, Saron R. S. [1] ; Leidens, Leonardo M. [1] ; Maia da Costa, Marcelo E. H. [2] ; Alvarez, Fernando [3] ; Burgo, Thiago A. L. [4, 5] ; Michels, Alexandre F. [6, 1] ; Figueroa, Carlos A. [7, 1]
Número total de Autores: 8
Afiliação do(s) autor(es):
[1] UCS, PGMAT, BR-95070560 Caxias Do Sul, RS - Brazil
[2] Pontificia Univ Catolica Rio de Janeiro PUC Rio, Dept Fis, BR-22451900 Rio De Janeiro, RJ - Brazil
[3] Univ Estadual Campinas, UNICAMP, Inst Fis Gleb Wataghin, BR-13083970 Campinas, SP - Brazil
[4] Univ Estadual Campinas, UNICAMP, Inst Quim, BR-13083970 Campinas, SP - Brazil
[5] Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS - Brazil
[6] Univ Fed Rio Grande do Sul UFRGS, Inst Fis, Porto Alegre, RS - Brazil
[7] Plasmar Tecnol Ltda, BR-95030775 Caxias Do Sul, RS - Brazil
Número total de Afiliações: 7
Tipo de documento: Artigo Científico
Fonte: Physical Chemistry Chemical Physics; v. 20, n. 34, p. 21949-21959, SEP 14 2018.
Citações Web of Science: 2
Resumo

Hydrogenated amorphous carbon (a-C:H) thin films have a unique combination of properties that are fundamental in mechanical and electromechanical devices aimed at energy efficiency issues. The literature brings a wealth of information about the ultra-low friction (superlubricity) mechanism in a-C:H thin films. However, there is persistent controversy concerning the physicochemical mechanisms of contact mechanics at the atomic/molecular level and the role of electrical interactions at the sliding interface is still a matter of debate. We find that the hydrogenation of the outermost nanostructured surface atomic layers of a-C:H thin films is proportional to the surface potential and also to the friction forces arising at the sliding interface. A higher hydrogen-to-carbon ratio reduces the surface potential, directly affecting frictional forces by a less effective long-term interaction. The structural ultra-low friction (superlubricity) is attributed to a lower polarizability at the outermost nanostructured layer of a-C:H thin films due to a higher hydrogen density, which renders weaker van der Waals forces, in particular London dispersion forces. More hydrogenated nanodomains at the surface of a-C:H thin films are proposed to be used to tailor superlubricity. (AU)

Processo FAPESP: 12/10127-5 - Pesquisa e desenvolvimento de materiais nanoestruturados para aplicações eletrônicas e de física de superfícies
Beneficiário:Fernando Alvarez
Linha de fomento: Auxílio à Pesquisa - Temático