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CHARACTERISTICS OF HIGH TEMPERATURE VACUUM BRAZED WC-CO-NICRBSI FUNCTIONAL COMPOSITE COATINGS

1,2 PASCAL Dragos-Toader
Co-authors:
1,2 MUNTEAN Roxana 1,2 KAZAMER Norbert 2 MARGINEAN Gabriela 2 BRANDL Waltraut 1 SERBAN Viorel-Aurel
Institutions:
1 Department of Materials Science and Engineering, Politehnica University Timisoara, Piata Victoriei Nr.2, 300006 Timisoara, Timis, Romania, EU, dragos.pascal@student.upt.ro
2 Department of Materials Science and Testing, University of Applied Sciences Gelsenkirchen, Neidenburger Str 43, 45877 Gelsenkirchen, Germany, EU
Conference:
8th International Conference on Nanomaterials - Research & Application, Hotel Voronez I, Brno, Czech Republic, EU, October 19th - 21st 2016
Proceedings:
Proceedings 8th International Conference on Nanomaterials - Research & Application
Pages:
775-780
ISBN:
978-80-87294-71-0
ISSN:
2694-930X
Published:
17th March 2017
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
532 views / 385 downloads
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Abstract

The present work aims to investigate the characteristics of high temperature vacuum brazed WC-Co-NiCrBSi coatings deposited on 16MnCr5 steel substrate. The coatings characteristics like morphology, microstructure, chemical composition and the appearance of the interface with the substrate have been analyzed by means of Scanning Electron Microscopy (SEM) combined with energy-dispersive X-ray spectroscopy. The hardness profile of the cladding is evaluated with the help of a Vickers microhardness tester. Size, occurrence and distribution of pores and microcracks has been estimated using image processing of SEM micrographs. X-ray diffraction measurements performed on the on the brazed composite cladding, have been done in order to identify possible phase transformations during the thermal treatment. Tribological behavior is assessed with the aid of a tribometer utilizing a pin-on-disk testing arrangement. Corrosion resistance is appraised using the potentiodynamic polarization method in 3.5% NaCl solution at room temperature in a three-electrode cell configuration. This coating technology makes possible the deposition of high quality hardfacings, with minimal influence on metallic substrate. The achieved porosity degree (approximately 1%) is similar to the values reported in literature. It was found that the mean coefficient of friction is approximately two times lower for the WC-Co-NiCrBSi composite, compared to 16MnCr5. Consequently, the wear rate of the coating is more than 20 times lower than that of the unprotected substrate material. The electrochemical measurements resulted in a lower corrosion current density, correlated with a significant improvement in the corrosion behavior.

Keywords: vacuum brazed coatings, WC-Co-NiCrBSi characteristics, wear and corrosion resistance

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