Microstructure and Wear Resistance of WC/Fe Plasma Sprayed Coatings Modified by Laser Remelting

ZHAO Yun-cai, SHANGGUAN Xu-chao, ZHANG Ji-wu, HE Wen

Surface Technology ›› 2018, Vol. 47 ›› Issue (3) : 20-27.

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Surface Technology ›› 2018, Vol. 47 ›› Issue (3) : 20-27. DOI: 10.16490/j.cnki.issn.1001-3660.2018.03.004
Special Topic—Laser Surface Modification Technology

Microstructure and Wear Resistance of WC/Fe Plasma Sprayed Coatings Modified by Laser Remelting

  • ZHAO Yun-cai, SHANGGUAN Xu-chao, ZHANG Ji-wu, HE Wen
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Abstract

The work aims to improve microstructure of plasma sprayed WC/Fe composite ceramic coating and improve corresponding wear resistance, and study wear resistance of laser remelted coating at different temperature. The plasma sprayed WC/Fe composite ceramic coating was treated by adopting laser remelting technique. Microstructure characteristic, phase composition and microhardness of the plasma sprayed coating before and after laser remelting was tested and characterized with scanning electron microscope (SEM), X-ray diffractometer (XRD) and microhardness tester, respectively. Wear resistance of the laser remelted coating was compared and investigated at 25 ℃, 200 ℃ and 400 ℃ with a friction and wear tester. Plasma sprayed WC/Fe composite ceramic coating exhibited layered structure. After laser remelting, defects such as lamellar structure and pores nearly disappeared, top structures in laser cladding zone were isometric crystals and fine dendrites. Bottom structures in the zone were afterbirth-like crystals, and structures in coating-substrate binding zone were coarse dendrites, and the coating had metallurgical bonding with the substrate. Dispersion strengthening effect of high hardness compounds such as WC, W2C, M23C6 and Ni6BSi2 in the laser remelted coating made microhardness of the laser remelted coating increase by nearly 1 time than that of the original plasma sprayed coating. Worn sub-surface of the laser remelted coating was the most intact at 25 ℃, and micro-cracks appeared at 400 ℃. Remelting can eliminate various defects of plasma sprayed coating to form dense coating. The remelted coating exhibits different wear mechanisms at different temperature and the best wear resistance at 25 ℃.

Key words

plasma spraying; WC/Fe ceramic coating; laser remelting; dispersion strengthening; wear resistance; wear mechanism

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ZHAO Yun-cai, SHANGGUAN Xu-chao, ZHANG Ji-wu, HE Wen. Microstructure and Wear Resistance of WC/Fe Plasma Sprayed Coatings Modified by Laser Remelting[J]. Surface Technology. 2018, 47(3): 20-27

Funding

Supported by the National Natural Science Foundation of China(51565017); High-end Bearing Friction Technology and Application of National Local Joint Engineering Laboratory Open-end Fund Project(201713); Jiangxi Province Natural Science Foundation(2012BAB206026); Jiangxi Provincial Department of Education Funded Projects(GJJ14424)
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