W--Cr--C coatings with different chromium contents (0--3 wt.%) were fabricated on the tungsten substrates by spark plasma sintering (SPS) method from the graphite and chromium mixed powders. SEM and XRD were exploited to analyze the effect of Cr contents on the microstructure of coatings. It was found that the abnormal hollow WC grains disappeared with addition of Cr less than 2%, and the microstructures were largely refined and densified. With further increase of Cr addition, the grains changed slightly but the densification was reduced. The most dense coating was achieved at 1 wt.% Cr. Corrosion behavior of the W--Cr--C coatings were investigated by impedance spectrum and potentiodynamic polarization tests. Results suggested that the W--1Cr--C coated W sample exhibited the lowest corrosion current density and highest corrosion potential due to the most densified microstructure, indicating that the addition of Cr at 1 wt.% was optimal for WC coating against corrosion.
. [J]. Frontiers of Materials Science, 2015, 9(1): 77-84.
Yan JIANG,Jun-Feng YANG,Qian-Feng FANG. Effect of chromium content on microstructure and corrosion behavior of W--Cr--C coatings prepared on tungsten substrate. Front. Mater. Sci., 2015, 9(1): 77-84.
Guo S Q, Ge C C, Zhou Z J, . Research development of tungsten coatings used as plasma facing materials for fusion reactor. Materials Review, 2010, 24(3): 93–96 (in Chinese)
2
Sommer W F, Maloy S A, Louthan M R, . Performance of a clad tungsten rod spallation neutron source target. Nuclear Technology, 2005, 151(3): 303–313
3
Daemen L L, Kanner G S, Lillard R S, . Modeling of water radiolysis at spallation neutron sources. Conference: 126, Annual Meeting of the Minerals, Metals and Materials Society, Orlando, FL, USA, 1998, 83–91
4
Noriaki N J, Keisuke K, Noboru A, . Corrosion resistance of tungsten and tungsten alloys for spallation target in stagnant and flowing water. Journal of the Japan Institute of Metals, 2002, 66: 1107–1115
5
Nelson A T, O’Toole J A, Valicenti R A, . Fabrication of a tantalum-clad tungsten target for LANSCE. Journal of Nuclear Materials, 2012, 431(1–3): 172–184
6
Yu L G, Khor K A, Li H, . Restoring WC in plasma sprayed WC–Co coatings through spark plasma sintering (SPS). Surface and Coatings Technology, 2004, 182(2–3): 308–317
7
Shackelford J F, Alexander W. CRC Materials Science and Engineering Handbook. 3rd ed. Boca Raton: CRC Press LLC, 2001, 430
8
Park H K, Youn H J, Lee S M, . Consolidation of ultra fine WC–Co hard materials by a spark plasma sintering method and their mechanical properties. Journal of Ceramic Processing Research, 2011, 12: 304–309
9
Machado I F, Girardini I, Lonardelli I, . The study of ternary carbides formation during SPS consolidation process in the WC–Co–steel system. International Journal of Refractory Metals & Hard Materials, 2009, 27(5): 883–891
10
Wentzel E J, Allen C. The erosion-corrosion resistance of tungsten carbide hard metals. International Journal of Refractory Metals & Hard Materials, 1997, 15(1–3): 81–87
11
Saito H, Iwabuchi A, Shimizu T. Effects of Co content and WC grain size on wear of WC cemented carbides. Wear, 2006, 261(2): 126–132
12
Bouaouadja N, Hamidouche M, Osmani H, . Fracture toughness of WC–Co cemented carbides at room temperature. Journal of Materials Science Letters, 1994, 13(1): 17–19
13
Sutthiruangwong S, Mori G. Corrosion properties of Co-based cemented carbides in acidic solutions. International Journal of Refractory Metals & Hard Materials, 2003, 21(3–4): 135–145
14
Kellner F J J, Hildebrand H, Virtanen S. Effect of WC grain size on the corrosion behavior of WC–Co based hardmetals in alkaline solutions. International Journal of Refractory Metals & Hard Materials, 2009, 27(4): 806–812
15
Qiao Z H, R?thel J, Berger L M, . Investigation of binderless WC–TiC–Cr3C2 hard materials prepared by spark plasma sintering (SPS). International Journal of Refractory Metals & Hard Materials, 2013, 38: 7–14
Wu Q L, Li W G. The microstructure and wear properties of laser-clad WC–Cr3C2 cermet coating on steel substrate. Materials Transactions, 2011, 52(3): 560–563
18
Xue M P, Han B, Wang Y, . Microstructure and corrosion resistance properties of Ni based WC/Cr3C2 coating prepared by laser cladding. Laser & Optoelectronics Progress, 2011, 48(9): 82–87 (in Chinese)
19
Sun L, Jia C C, Cao R J, . Effect of Cr3C2 additions on the densification, grain growth and properties of ultrafine WC–11Co composites by spark plasma sintering. International Journal of Refractory Metals & Hard Materials, 2008, 26(4): 357–361
20
Jiang Y, Yang J F, Xie Z M, . Corrosion resistance of W–Cr–C coatings fabricated by spark plasma sintering method. Surface and Coatings Technology, 2014, 254: 202–206
21
Jiang Y, Yang J F, Zhuang Z, . Characterization and properties of tungsten carbide coatings fabricated by SPS technique. Journal of Nuclear Materials, 2013, 433(1–3): 449–454
22
Wu E X, Lei Y W. Effect of inhibitor on ultrafine grained cemented carbides. Cemented Carbides, 2002, 19(3): 136–139
23
Li N, Qiu Y X, Zhang W, . Influence and function of inhibitor VC/Cr3C2 on the grain growth in super fine WC–Co cermets. Rare Metal Materials and Engineering, 2007, 36(10): 1763–1766 (in Chinese)
24
Cao C N, Zhang J Q. An Introduction to Electrochemical Impedance Spectroscopy. Beijing: Science Press, 2002 (in Chinese)
25
Ahn S H, Yoo J H, Choi Y S, . Corrosion behavior of PVD-grown WC–(Ti1-xAlx)N films in a 3.5% NaCl solution. Surface and Coatings Technology, 2003, 162(2–3): 212–221
26
Aw P K, Tan A L K, Tan T P, . Corrosion resistance of tungsten carbide based cermet coatings deposited by high velocity oxy-fuel spray process. Thin Solid Films, 2008, 516(16): 5710–5715
27
Zhu Q Z, Xue W B, Lu L, . Preparation of microarc oxidation coating on (Al2O3–SiO2)sf/AZ91D magnesium matrix composite and its electrochemical impedance spectroscopic analysis. Acta Metallurgica Sinica, 2011, 47(1): 74–80 (in Chinese)
28
Manohar A K, Bretschger O, Nealson K H, . The use of electrochemical impedance spectroscopy (EIS) in the evaluation of the electrochemical properties of a microbial fuel cell. Bioelectrochemistry, 2008, 72(2): 149–154
