Influence of aging in the temperature range 250–350 °C on the tribological performance of a WC-CoCr coating produced by HVOF. (September 2018)

• Record Type: Journal Article
• Authors: Rovatti, L.; Lecis, N.; Dellasega, D.; Russo, V.; Gariboldi, E.
• Is Part Of: International journal of refractory metals & hard materials. Volume 75(2018)
• Page Start: 218
• Page End: 224
• Publication Date: 2018-09
• Subjects: WC-CoCr -- HVOF -- Aging -- Wear -- Oxidation; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2018.04.017
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Coatings made of tungsten carbides in a metallic matrix are key materials for wear-resistant industrial components. However, the thermal stability could represent a critical parameter for the future development of these WC-based composites, in view of increasing their service temperature. In the present study the evolution after thermal exposure of a WC-CoCr coating deposited by HVOF in the temperature range 250–350 °C up to 345 h was monitored. The analysis was carried out combining surface characterization (SEM, GDOES and Raman) with hardness and tribological behaviour. The results showed a detrimental effect of the oxidation on the wear behaviour of the WC-based material, already noticeable after short aging at the upper temperature. In fact, while in the untreated samples the worn products contributed to achieve a low and stable friction coefficient (COF), in the aged coatings a COF increase was observed. The worsening was due to the presence of porous and not-protective oxides grown during aging that overcome the lubricant oxidative effect occurred during sliding. Graphical abstract: Unlabelled Image Highlights: The effect of heat treatments in air on HVOF WCCoCr coatings is studied up to 350 °C. Surface evolution is characterized by hardness, pin on disk, GDOES, Raman and SEM. The friction coefficient is below 0.25 in the as received coating. Long aging produces not-protective oxides that increase wear rate and COF above 0.4.