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Tribo-mechanical properties of CoCr and NiWCrB hardfacing superalloy coating systems

Marwan Azzi, Luc Vernhes, Étienne Bousser and Jolanta-Ewa Sapieha

Paper (2014)

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Abstract

Wear of materials is a serious problem facing industry especially in mechanical applications where moving parts are continuously subjected to friction. Hard coatings prepared by a variety of processes are nowadays considered as effective solutions to protect components against wear. Examples of such processes are: thermal spray coating, vacuum-based coating and hardfacing. In this paper, we study the mechanical, tribological and corrosion properties of two hard coating systems: CoCr Stellite 6 (ST6) hardfacing on 316 stainless steel and NiWCrB Colmonoy 88 (C88) thermal spray coating on Inconel 718. The effect of gas nitriding on the microstructure and wear performance of these coating systems is investigated. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used for microstructural analysis. Micro-indentation technique was utilized to measure the surface and cross-sectional hardness of the coatings. Rockwell indentation technique was used to evaluate coating adhesion in accordance with CEN/TS 1071-8. Pin-on-disk tests were conducted to assess the tribological performance of the coatings. Microstructural analysis showed that ST6 has a cobalt matrix in the form of dendrites reinforced with metal carbide particles whereas C88 has a Nickel matrix reinforced mainly with metal boride particles. ST6 and C88 improved significantly the wear resistance of their corresponding substrates. This is mainly due to good adhesion and high hardness of the coatings; HR15N values of ST6 and C88 were almost 85 as compared to 61 and 80 for 316 and INC substrates, respectively. ST6 was found to improve significantly the corrosion resistance of 316 whereas C88 decreased the corrosion performance of INC. Moreover, nitriding treatment was found to improve significantly the wear resistance of 316 and INC, however, in the case of ST6, nitriding was beneficial in terms of wear resistance only at relatively low load.

Uncontrolled Keywords

Coatings, Mechanical properties, Superalloys, Nitriding, Wear, Wear resistance, Adhesion, Corrosion, Metals, Particulate matter, Spraying (Coating processes), Tribology, Cobalt, Corrosion resistance, Disks, Friction, Nickel, Scanning electron microscopy, Spectroscopy, Stainless steel, Stress, Vacuum, X-ray diffraction

Additional Information: Paper no. IMECE2014-39372, V014T11A028
Department: Department of Engineering Physics
Funders: GRSNG / NSERC - Discovery Grant
PolyPublie URL: https://publications.polymtl.ca/12795/
Conference Title: ASME International Mechanical Engineering Congress & Exposition (IMECE 2014)
Conference Location: Montréal, QC, Canada
Conference Date(s): 2014-11-14 - 2014-11-20
Publisher: American Society of Mechanical Engineers (ASME)
DOI: 10.1115/imece2014-39372
Official URL: https://doi.org/10.1115/imece2014-39372
Date Deposited: 18 Apr 2023 15:07
Last Modified: 05 Apr 2024 10:52
Cite in APA 7: Azzi, M., Vernhes, L., Bousser, É., & Sapieha, J.-E. (2014, November). Tribo-mechanical properties of CoCr and NiWCrB hardfacing superalloy coating systems [Paper]. ASME International Mechanical Engineering Congress & Exposition (IMECE 2014), Montréal, QC, Canada (10 pages). https://doi.org/10.1115/imece2014-39372

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