Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications
Abstract
1. Introduction
2. Materials and Methods
2.1. Materials Preparation
2.2. Characterization
2.3. Hardness Tests
3. Results and Discussion
3.1. As-Sintered WC-Fe-8Cr Materials
3.2. Formation of Coating
3.3. Coating Structure
3.4. Coating Hardness
4. Conclusions
- The coating formation kinetics show that growth is dominated by the formation of iron silicide. By analyzing the growth kinetics as trade-off between transport within the carbide grains and the binder, it is shown that the two-part, passively oxidizing (protective) structure will be dominant at high volume fractions of binder and high coating temperatures. The required parameters are typical for cWCs and pack cementation, respectively, suggesting that a protective coating will be observed under a range of conditions and cWC compositions.
- The most surprising aspect of this study was the very high hardness of the coating, which was about 20% higher than that of the substrate. By analyzing the coating structure using quantitative diffraction measurements and high-resolution electron microscopy, the hardness increase was attributed to nano-scale SiC laths formed within the WSi2 domains, which have not been previously reported. The impressive hardness of the coating shows promise for engineering applications.
- The porous region immediately below the substrate had a hardness value 14% lower than the bulk, which was explained via a net transport of FeCr binder towards the coating/substrate interface. This porous region is potentially detrimental to the coating’s properties but could be mitigated by enhancing the near-surface binder content or using liquid phase heat-treatments after coating deposition.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
- Clery, D. The new shape of fusion. Science 2015, 348, 854–856. [Google Scholar] [CrossRef] [PubMed]
- Roebuck, B.; Almond, E.A. Deformation and fracture processes and the physical metallurgy of WC–Co hardmetals. Int. Mater. Rev. 1988, 33, 90–112. [Google Scholar] [CrossRef]
- Shatov, A.V.; Ponomarev, S.S.; Firstov, S.A. Hardness and Deformation of Hardmetals at Room Temperature. In Comprehensive Hard Materials; Sarin, V.K., Ed.; Elsevier: Oxford, UK, 2014; pp. 267–299. ISBN 978-0-08-096528-4. [Google Scholar]
- Shatov, A.V.; Ponomarev, S.S.; Firstov, S.A. Fracture and Strength of Hardmetals at Room Temperature. In Comprehensive Hard Materials; Sarin, V.K., Ed.; Elsevier: Oxford, UK, 2014; pp. 301–343. ISBN 978-0-08-096528-4. [Google Scholar]
- Matthews, G.F.; Brezinsek, S.; Chapman, I.; Hobirk, J.; Horton, L.D.; Maggi, C.; Nunes, I.; Rimini, F.G.; Sips, G.; De Vries, P. The second phase of JET operation with the ITER-like wall. Phys. Scr. 2014, 2014, 014015. [Google Scholar] [CrossRef]
- Gilbert, M.R.; Fleming, M.; Sublet, J.-C. Automated inventory and material science scoping calculations under fission and fusion conditions. Nucl. Eng. Technol. 2017, 49, 1346–1353. [Google Scholar] [CrossRef]
- Windsor, C.G.; Morgan, J.G.; Buxton, P.F.; Costley, A.E.; Smith, G.D.W.; Sykes, A. Modelling the power deposition into a spherical tokamak fusion power plant. Nucl. Fusion 2016, 57, 036001. [Google Scholar] [CrossRef]
- Windsor, C.G.; Morgan, J.G. Neutron and gamma flux distributions and their implications for radiation damage in the shielded superconducting core of a fusion power plant. Nucl. Fusion 2017, 57, 116032. [Google Scholar] [CrossRef]
- Menard, J.E.; Brown, T.; El-Guebaly, L.; Boyer, M.; Canik, J.; Colling, B.; Raman, R.; Wang, Z.; Zhai, Y.; Buxton, P. Fusion nuclear science facilities and pilot plants based on the spherical tokamak. Nucl. Fusion 2016, 56, 106023. [Google Scholar] [CrossRef]
- Hong, B.G.; Hwang, Y.S.; Kang, J.S.; Lee, D.W.; Joo, H.G.; Ono, M. Conceptual design study of a superconducting spherical tokamak reactor with a self-consistent system analysis code. Nucl. Fusion 2011, 51, 113013. [Google Scholar] [CrossRef]
- Webb, W.W.; Norton, J.T.; Wagner, C. Oxidation Studies in Metal-Carbon Systems. J. Electrochem. Soc. 1956, 103, 112–117. [Google Scholar] [CrossRef]
- Kieffer, R.; Kölbl, F. Über das Zunderverhalten und den Oxydationsmechanismus warm-und zunder-fester Hartlegierungen, insbesondere solcher auf Titancarbid-Basis. Z. Anorg. Chem. 1950, 262, 229–247. [Google Scholar] [CrossRef]
- Humphry-Baker, S.A.; Lee, W.E. Tungsten carbide is more oxidation resistant than tungsten when processed to full density. Scr. Mater. 2016, 116, 67–70. [Google Scholar] [CrossRef]
- Humphry-Baker, S.A.; Marshall, J.M.; Smith, G.D.W.; Lee, W.E. Thermophysical properties of Co-free WC-FeCr hardmetals. In Proceedings of the 19th Plansee Seminar, Reutte, Autria, 29 May–2 June 2017. [Google Scholar]
- Haneda, K.; Morrish, A.H. Oxidation of aerosoled ultrafine iron particles. Nature 1979, 282, 186–188. [Google Scholar] [CrossRef]
- Maisonnier, D.; Cook, I.; Pierre, S.; Lorenzo, B.; Edgar, B.; Karin, B.; Luigi, D.P.; Robin, F.; Luciano, G.; Stephan, H.; et al. The European power plant conceptual study. Fusion Eng. Des. 2005, 75–79, 1173–1179. [Google Scholar] [CrossRef]
- Cifuentes, S.C.; Monge, M.A.; Pérez, P. On the oxidation mechanism of pure tungsten in the temperature range 600–800 °C. Corros. Sci. 2012, 57, 114–121. [Google Scholar] [CrossRef]
- Humphry-Baker, S.A.; Peng, K.; Lee, W.E. Oxidation resistant tungsten carbide hardmetals. Int. J. Refract. Met. Hard Mater. 2017, 66, 135–143. [Google Scholar] [CrossRef]
- Marshall, J.M.; Kusoffsky, A. Binder phase structure in fine and coarse WC–Co hard metals with Cr and V carbide additions. Int. J. Refract. Met. Hard Mater. 2013, 40, 27–35. [Google Scholar] [CrossRef]
- ISO 4499-3:2016 Hardmetals—Metallographic Determination of Microstructure—Part 3: Measurement of Microstructural Features in Ti (C, N) and WC/Cubic Carbide Based Hardmetals; ISO: Geneva, Switzerland, 2016.
- Mingard, K.P.; Roebuck, B.; Marshall, J.; Sweetman, G. Some aspects of the structure of cobalt and nickel binder phases in hardmetals. Acta Mater. 2011, 59, 2277–2290. [Google Scholar] [CrossRef]
- Oliver, W.C.; Pharr, G.M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res. 1992, 7, 1564–1583. [Google Scholar] [CrossRef]
- Schubert, W.D.; Fugger, M.; Wittmann, B.; Useldinger, R. Aspects of sintering of cemented carbides with Fe-based binders. Int. J. Refract. Met. Hard Mater. 2015, 49, 110–123. [Google Scholar] [CrossRef]
- Wittmann, B.; Schubert, W.-D.; Lux, B. WC grain growth and grain growth inhibition in nickel and iron binder hardmetals. Int. J. Refract. Met. Hard Mater. 2002, 20, 51–60. [Google Scholar] [CrossRef]
- Guillermet, A. The Co-Fe-Ni-W-C Phase Diagram: A Thermodynamic Description and Calculated Sections for (Co-Fe-Ni)-Bonded Cemented WC Tools. Z. Metallkde 1989, 80, 83–94. [Google Scholar]
- Petersson, A. Cemented Carbide Sintering : Constitutive Relations and Microstructural Evolution. Ph.D. Thesis, KTH Royal Institute of Technology, Stockholm, Sweden, 2004. [Google Scholar]
- Kim, H.-S.; Yoon, J.-K.; Kim, G.-H.; Doh, J.-M.; Kwun, S.-I.; Hong, K.-T. Growth behavior and microstructure of oxide scales grown on WSi 2 coating. Intermetallics 2008, 16, 360–372. [Google Scholar] [CrossRef]
- Lee, K.-H.; Yoon, J.-K.; Lee, J.-K.; Doh, J.-M.; Hong, K.-T.; Yoon, W.-Y. Growth kinetics of W5Si3 layer in WSi2/W system. Surf. Coat. Technol. 2004, 187, 146–153. [Google Scholar] [CrossRef]
- Gage, P.P.; Bartlett, R.W. Diffusion kinetics affecting formation of silicide coatings on molybdenum and tungsten. Trans. Met. Soc. AIME 1965, 233, 4634278. [Google Scholar]
- Kharatyan, S.L.; Chatilyan, H.A.; Harutyunyan, A.B. High-Temperature Silicon Diffusivities in Mo5Si3 and W5Si3 Phases. Defect Diffus. Forum 2001, 194–199, 1557–1562. [Google Scholar]
- Sen, U.; Ozdemir, O.; Yilmaz, S.; Sen, S. Kinetics of iron silicide deposited on AlSi D2 steel by pack method. In Proceedings of the 22nd International Conference on Metallurgy and Materials, Brno, Czech Republic, 15–17 May 2013. [Google Scholar]
- Schwarzkopf, M. Kinetik der Bildung von Mischkarbidfreien Randzonen auf Hartmetallen. Ph.D. Thesis, Montanuniversitat Leoben, Leoben, Austia, 1987. [Google Scholar]
- Frykholm, R. Effect of Cubic Phase Composition on Gradient Zone Formation in Cemented Carbides. Int. J. Refract. Met. Hard Mater. 2001, 19, 527–538. [Google Scholar] [CrossRef]
- Shackelford, J.F.; Han, Y.-H.; Kim, S.; Kwon, S.-H. CRC Materials Science and Engineering Handbook; CRC Press: Boca Raton, FL, USA, 2016. [Google Scholar]
- Roebuck, B. Terminology, testing, properties, imaging and models for fine grained hardmetals. Int. J. Refract. Met. Hard Mater. 1995, 13, 265–279. [Google Scholar] [CrossRef]
- Nabarro, F.R.N.; Shrivastava, S.; Luyckx, S.B. The size effect in micro-indentation. Philos. Mag. 2006, 86, 4173–4180. [Google Scholar] [CrossRef]
- Milekhine, V.; Onsøien, M.I.; Solberg, J.K.; Skaland, T. Mechanical properties of FeSi (ε), FeSi2 (ζα) and Mg2Si. Intermetallics 2002, 10, 743–750. [Google Scholar] [CrossRef]
- García, J.; Englund, S.; Haglöf, F. Controlling cobalt capping in sintering process of cermets. Int. J. Refract. Met. Hard Mater. 2017, 126–133. [Google Scholar] [CrossRef]
Sample | Shrinkage [%] | Density [g cm−3] | Sintered WC d50 [µm] | HV30 [kgf mm−2] | K1c [MPa m0.5] |
---|---|---|---|---|---|
10 wt.% Fe-8Cr | 17.7 | 14.14 | 0.8 | 1490 | 8.2 |
Phase | Vf | Hardness (GPa) |
---|---|---|
WC | 0.04 | 23.5 |
FeSi | 0.3 | 9.3 |
WSi2 | 0.43 | 10.7 |
SiC | 0.22 | 31.9 |
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Share and Cite
Humphry-Baker, S.; Marshall, J. Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications. Coatings 2018, 8, 247. https://doi.org/10.3390/coatings8070247
Humphry-Baker S, Marshall J. Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications. Coatings. 2018; 8(7):247. https://doi.org/10.3390/coatings8070247
Chicago/Turabian StyleHumphry-Baker, Samuel, and Jessica Marshall. 2018. "Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications" Coatings 8, no. 7: 247. https://doi.org/10.3390/coatings8070247
APA StyleHumphry-Baker, S., & Marshall, J. (2018). Structure and Properties of High-Hardness Silicide Coatings on Cemented Carbides for High Temperature Applications. Coatings, 8(7), 247. https://doi.org/10.3390/coatings8070247