Dry Sliding Wear Resistance of Cobalt Boride Coatings Formed on ASTM F1537 Alloy
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JMEPEG https://doi.org/10.1007/s11665-019-04012-3
Dry Sliding Wear Resistance of Cobalt Boride Coatings Formed on ASTM F1537 Alloy I. Campos-Silva, R.C. Vega-Moro´n, C.D. Rese´ndiz-Caldero´n, D. Bravo-Ba´rcenas, O.L. Eryilmaz, O. Kahvecioglu-Feridun, and G. Rodrı´guez-Castro (Submitted September 28, 2018; in revised form January 30, 2019) New results about the wear resistance of CoB-Co2B coatings under dry sliding conditions were estimated in this work. The cobalt boride coatings were developed at the surface of the ASTM F1537 alloy by means of the powder-pack boriding process using two experimental conditions: 1223 K with 6 h of exposure and 1273 K with 10 h of exposure. Before the sliding wear tests, Vickers depth-sensing microindentation tests were conducted on the cross section of the cobalt boride coatings to estimate the distribution of hardness, Youngs modulus, and residual stresses. Otherwise, the sliding wear tests were performed on both boriding conditions and on the untreated material, using a ball-on-flat configuration comprised of an alumina ball as a counterpart with applied loads between 5 and 20 N. The wear rates of the borided ASTM F1537 alloy were ranged between 4.02 and 8.91 3 1026 mm3 N21 m21 compared with the values of the untreated material (13.90 and 15.78 3 1026 mm3 N21 m21) for the overall set of experimental conditions; nevertheless, the influence of boriding conditions (1273 K with 10 h of exposure) tended to increase the CoB coating thickness, developing a more brittle layer that decreased the sliding wear resistance at the surface of the borided ASTM F1537 alloy. Finally, the presence of failure mechanisms on the surface of the wear tracks was analyzed for both borided ASTM F1537 alloy and untreated material. Keywords
boriding, cobalt boride coatings, failure mechanisms, friction coefficient, wear resistance
1. Introduction Cobalt-based alloys have been used in biomedical field because of their good mechanical, chemical properties, and biocompatibility (Ref 1, 2). However, problems, including wear and fretting corrosion, can lead to loosening of the material, especially for components experiencing high loads and hard contacts (Ref 3, 4). In this case, different surface methods have employed to increase the durability and longevity of biomaterials by application of a coating (Ref 5, 6). Particularly, during the last years, a thermochemical reaction method denominated boriding, which involves the use of specially formulated boron-yielding material, heated to temperatures between 1048 and 1273 K, was applied on the surface of cobalt-based alloys (Ref 7-14). During the process, boron I. Campos-Silva, R.C. Vega-Moro´n, and G. Rodrı´guez-Castro, Instituto Polite´cnico Nacional, Grupo Ingenierı´a de Superficies, SEPIESIME, U.P. Adolfo Lo´pez Mateos, Zacatenco, 07738 Ciudad de Mexico, Mexico; C.D. Rese´ndiz-Caldero´n, Tecnolo´gico de Monterrey Campus Estado de Me´xico, Departamento de Mecatro´nica/Escuela de Ingenierı´a y Ciencias, Carretera al Lago de Guadalupe km. 4.5, 52926 Atizapa´n de Zaragoz
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