Cailiao gongcheng (Dec 2021)

Friction and high temperature oxidation resistance of laser cladding NiCrCoAlY-Cr3C2 composite coating on TC4 titanium alloy

  • QIN Xin,
  • QI Wen-jun,
  • ZUO Xiao-gang

DOI
https://doi.org/10.11868/j.issn.1001-4381.2020.000989
Journal volume & issue
Vol. 49, no. 12
pp. 107 – 114

Abstract

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In order to improve the surface friction, wear and high temperature oxidation resistance of TC4 titanium alloy, NiCrCoAlY+20%(mass fraction) Cr3C2 mixed powder was selected as the cladding powder to prepare NiCrCoAlY-Cr3C2 composite coating on the surface of TC4 titanium alloy by using laser cladding technology. The microstructure and phase composition of the coating were analyzed by OM, SEM, XRD, EDS, etc.The microhardness of the coating was measured by HXD-1000TB tester. MMG-500 three-body wear tester and WS-G150 smart muffle furnace were used to test the friction, wear and high temperature oxidation resistance of the coating and substrate. The results show that the laser cladding technology can be used to prepare the good composite coating on the surface of TC4 titanium alloy without cracks and pores. The microstructure of the cladding zone is dense, mostly needle-like crystals and dendrites.The microstructure of the bonding zone is mainly composed of planar crystals, cellular crystals and dendrites, which generates a variety of products including the carbides, oxides and intermetallic compounds that can improve wear resistance and high temperature oxidation resistance. The maximum microhardness of the composite coating is 1344HV, which is about 3.8 times of the 350HV of the titanium alloy substrate.The friction factor of the composite coating is 0.2-0.3, which is significantly lower than the friction factor of the titanium alloy substrate of 0.6-0.7. Under the same conditions, the wear mass loss of the composite coating is 0.00060 g, which is 0.9% of that of 0.06508 g of titanium alloy substrate. After oxidation at 850℃ for 100 h, the oxidation mass gain of the composite coating is 6.01 mg·cm-2, which is about 24% of that of 25.10 mg·cm-2 of titanium alloy substrate. Laser cladding technology effectively improves the friction and wear performance and high temperature oxidation resistance of the TC4 titanium alloy surface.

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