| ZHOU Haodong,LIU Hongjun,YE Jianzhong,CAO Chi,ZHANG Lei.Wear Resistance of Supersonic Flame-sprayed Diamond/Ni60 Composite Coatings[J],54(11):252-263 |
| Wear Resistance of Supersonic Flame-sprayed Diamond/Ni60 Composite Coatings |
| Received:September 11, 2024 Revised:February 20, 2025 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.11.022 |
| KeyWord:scum ball value composite coating Ni60 nickel-plated diamond HVAF supersonic flame-spraying tribological properties |
| Author | Institution |
| ZHOU Haodong |
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China;Wenzhou Engineering Institute of Pump & Valve, Lanzhou University of Technology, Zhejiang Wenzhou , China |
| LIU Hongjun |
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou , China |
| YE Jianzhong |
Chaoda Valves Group Co., Ltd., Zhejiang Wenzhou , China |
| CAO Chi |
Wenzhou Engineering Institute of Pump & Valve, Lanzhou University of Technology, Zhejiang Wenzhou , China |
| ZHANG Lei |
Chaoda Valves Group Co., Ltd., Zhejiang Wenzhou , China |
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| Abstract: |
| The work aims to enhance the wear resistance of Ni60 coatings prepared by HVAF supersonic flame-spraying technology by incorporating nickel-plated diamond particles and optimizing the friction pair materials, thereby extending the service life of scum ball values. The scum ball values are critical components in industrial processes, particularly coal chemical industry, where they are subject to severe wear due to the abrasive nature of slag. Therefore, improving their wear resistance is essential for reducing maintenance costs and downtime. The HVAF technology was employed to deposit diamond/Ni60 composite coatings with varying mass fractions of diamond particles. The supersonic flame spraying process with compressed air as a combustible gas has the following process parameters, including the powder feeding volume of about 3 g/s, the spraying distance of 260 mm, the compressed air pressure of 78.4 psi (1 psi=6 894.757 29 Pa), the propane fuel pressure of 76.5 psi, and the nitrogen gas flow rate of 22 L/min. By this HVAF process, diamond/Ni60 composite coatings that were intact and well-bonded were successfully prepared. The phases in the coatings, except for diamond, were essentially consistent with the original Ni60 powder. The microstructure and phase composition of the coatings were characterized with optical microscopy, scanning electron microscopy (EM-30AX+), X-ray diffraction (DX-2700BH), and energy-dispersive spectroscopy. The reciprocating friction and wear test was completed on a multifunctional wear tester (MS M9000). The wear resistance of the coatings was evaluated through reciprocating friction and wear tests under different friction pair materials, specifically alumina and silicon nitride balls, to select suitable coating compatible materials in scum ball values. The diamond particles were evenly distributed throughout the Ni60 alloy matrix, with some nickel-plated diamond particles exhibiting signs of fragmentation, which was a common phenomenon in thermal spray processes due to the high impact forces and temperatures. The porosity levels of Ni60 and three diamond/Ni60 composite coatings were 0.647%, 0.962%, 0.913%, and 1.555%, respectively. The relative wear values of the four coatings tested against alumina balls were 0.06, 4.61, 4.54, and 16.2, indicating that the addition of diamond particles significantly reduced the wear compared to the pure Ni60 coating. During the test against silicon nitride balls, the relative wear values were 0.01, 1.33, 2.50, and 0.33, respectively. The friction coefficient curves under both alumina and silicon nitride wear conditions exhibited an initial increase followed by a decrease. The decrease in friction coefficient with alumina was attributed to the rolling and sliding of wear debris, which helped to reduce friction, while the decrease in silicon nitride was due to its self-lubricating properties. The addition of an appropriate amount of diamond particles significantly improves the wear resistance of the Ni60 coating. However, an excessive amount of diamond particles leads to an increase in porosity, thereby reducing wear resistance. The diamond/Ni60 composite coating with a diamond content of 37.5% demonstrates the best wear performance. Silicon nitride is considered to be a more suitable friction pair material for the composite coating due to its self-lubricating characteristics. The wear mechanism of the silicon nitride-diamond/Ni60 composite coating is primarily abrasive wear and oxidative wear, with some fatigue wear. The wear mechanism of the alumina-diamond/Ni60 composite coating is mainly abrasive wear with a small amount of adhesive wear and some fatigue wear. |
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