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Advances in Materials Science and Engineering
Volume 2015, Article ID 436597, 9 pages
http://dx.doi.org/10.1155/2015/436597
Research Article

Effect of Relative Humidity on the Tribological Properties of Self-Lubricating H3BO3 Films Formed on the Surface of Steel Suitable for Biomedical Applications

1Instituto Politécnico Nacional, UPIBI, Avenida Acueducto s/n, Barrio La Laguna Ticomán, 07340 México, DF, Mexico
2Gerencia de Proyectos Ambientales, Pemex Refinación, Piso 7 Torre Ejecutiva de Pemex, Marina Nacional 329, Colonia Petróleos Mexicanos, 11311 México, DF, Mexico
3Universidad Autónoma del Estado de México, Boulevard Universitario s/n, Predio San Javier, 54500 Atizapán de Zaragoza, MEX, Mexico
4Instituto Tecnológico de Tlalnepantla, Departamento de Postgrado, Avenida Instituto Tecnológico s/n, Colonia La Comunidad, Tlalnepantla de Baz, MEX, Mexico
5Instituto Tecnológico Superior de Poza Rica, Luis Donaldo Colosio Murrieta s/n, Arroyo del Maíz, 93230 Poza Rica, VER, Mexico

Received 28 May 2015; Accepted 10 August 2015

Academic Editor: Hongchao Kou

Copyright © 2015 E. Hernández-Sanchez et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The effect of environmental humidity on the self-lubricating properties of a thin film of boric acid (H3BO3) was evaluated. H3BO4 films were successfully formed on the surface of AISI 316L steel. The study was conducted on AISI 316L steel because of its use in biomedical applications. First, the samples were exposed to boriding to generate a continuous surface layer of iron borides. The samples were then exposed to a short annealing process (SAP) at 1023 K for 5 min and cooled to room temperature while controlling the relative humidity (RH). Five different RH conditions were tested. The purpose of SAP was to promote the formation of a surface film of boric acid from the boron atoms present in the iron boride layers. The presence of the boric acid at the surface of the borided layer was confirmed by Raman spectroscopy and X-ray diffraction (XRD). The self-lubricating capability of the films was demonstrated using the pin-on-disk technique. The influence of RH was reflected by the friction coefficient (FC), as the samples cooled with 20% of RH exhibited FC values of 0.16, whereas the samples cooled at 60% RH showed FC values of 0.02.