Effect of Atmospheric Plasma Spraying Power on Microstructure and Properties of WC-(W,Cr) 2 C-Ni Coatings
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JTTEE5 20:1150–1160 DOI: 10.1007/s11666-011-9661-x 1059-9630/$19.00 ASM International
Effect of Atmospheric Plasma Spraying Power on Microstructure and Properties of WC-(W,Cr)2C-Ni Coatings Guoliang Hou, Yulong An, Guang Liu, Huidi Zhou, Jianmin Chen, and Zujun Chen (Submitted November 7, 2010; in revised form April 9, 2011) WC-(W,Cr)2C-Ni coatings were prepared by atmospheric plasma spraying (APS) with different spraying powers. The effect of spraying power on microstructure, phase composition, hardness, fracture toughness, and oscillating dry friction and wear behaviors of the coatings were studied. Simultaneously, the microstructure and properties of the as-sprayed coatings were compared with those of WC-17Co coating prepared under the optimal spraying power. It was found that spraying power had significant effect on the molten degree of feedstock powder and phase composition as well as microstructure and properties of WC-(W,Cr)2C-Ni coatings. WC-(W,Cr)2C-Ni coating deposited at a moderate spraying power of 22.5 kW had the highest fracture toughness and the best wear resistance. WC-17Co coating obtained under the moderate spraying power had poor fracture toughness and wear resistance. Moreover, the four kinds of coatings were all dominated by subsurface cracking and removal of materials when sliding against Si3N4 ball under unlubricated conditions.
Keywords
atmospheric plasma spraying, microstructure, properties, spraying power, WC-(W,Cr)2C-Ni coating, WC-17Co coating
1. Introduction Thermally sprayed WC-based cermet coatings, owing to their advantageous combined hardness and toughness (Ref 1-5), are widely applied in machinery industries as wear-resistant materials. Among various WC-based coatings, WC-(W,Cr)2C-Ni coating with good oxidation resistance and corrosion resistance is considered as an excellent high temperature wear-resistant and corrosion wear-resistant material, which may be used to bridge the gap between WC-Co coating and Cr3C2-NiCr coating (Ref 6). Some publications about WC-(W,Cr)2C-Ni coating prepared by high-velocity oxy-fuel spraying (HVOF) can be found in the literature. For example, Nakajima and coworkers investigated the life-to-flaking property of HVOF-sprayed coating under lubricated rolling/sliding contact conditions and found that the life-to-flaking had relation with the thickness of coating and the properties of substrate (Ref 7, 8). Berger et al. (Ref 9-11) and Guoliang Hou, Yulong An, Guang Liu, Huidi Zhou, Jianmin Chen, and Zujun Chen, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; and Guoliang Hou, Yulong An, and Guang Liu, Graduate School of Chinese Academy of Sciences, Beijing 100049, China. Contact e-mails: [email protected] and [email protected].
1150—Volume 20(6) December 2011
Zimmermann et al. (Ref 12), respectively, studied the high temperature oxidation and dry sliding wear behavior as well as corrosion resistance of this kind of coating, which was also deposited by HVOF
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