Effect of Plasma Sprayed Ceramic and Cermet Coatings on Wear-Out Failure of High Temperature Ball Valve

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Abstract:

Three kinds of coating materials, namely Cr2O3 ceramic, Al2O3-TiO2 ceramic and WC-Co cermet, were screened and sprayed on the surface of valve ball by plasma spraying technology, and two kinds of brush plating materials, namely high speed nickel and nickel tungsten, were also screened and brush plated on the surface of valve seat by electrical brush technology. The microstructure and morphology of the plasma sprayed coatings were analyzed by means of scanning electron microscopy. The tribological properties of the plasma sprayed coatings sliding against the high speed nickel and nickel tungsten layers were investigated on a pin-on-disc friction and wear tester. The microhardness, thermal shock property and bonding strength of the coatings were also tested. The results indicate that the sealing pair composed of the valve ball with the plasma sprayed coating of Al2O3-TiO2 and the valve seat with the brush plating layer of nickel tungsten has the best combination property.

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Key Engineering Materials (Volumes 373-374)

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11-14

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March 2008

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© 2008 Trans Tech Publications Ltd. All Rights Reserved

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[1] 4 Cr2O3 vs Ni Cr2O3 vs NiW Al2O3-TiO2 vs Ni Al2O3-TiO2 vs NiW WC-Co vs Ni WC-Co vs NiW Sub vs Ni-alloy Fig. 2. Friction behaviors of different friction pairs. Distance [m] Friction coefficient A0 A1 A2 A3 A4 A5 A6 0 2 4 6 A0 Sub vs Ni-alloy A1 Cr2O3 vs Ni A2 Cr2O3 vs NiW A3 Al2O3-TiO2 vs Ni A4 Al2O3-TiO2 vs NiW A5 WC-Co vs Ni A6 WC-Co vs NiW pin disk Fig. 3. Wear rate of disk-and-pin testing after sliding 960m Wear rate [10-4mm 3/m] Samples.

DOI: 10.3390/chemistry1010003

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