| 摘要: |
| 为降低球墨铸铁激光熔覆过程中白口组织的含量，改善其高温摩擦学性能和耐腐蚀性能，采用激光熔覆技术，通过添加 Ni 基过渡层在球墨铸铁表面制备 Co 基涂层。利用 XRD、SEM、EDS 表征不同熔覆层的物相组成、微观结构。采用高温摩擦磨损试验机测试不同温度下 Co 基涂层与球墨铸铁的摩擦磨损性能，分析 Co 基涂层在不同温度下的磨损机理。利用电化学工作站测试 Co 基涂层与球墨铸铁的耐腐蚀性能。结果表明：Ni 基过渡层的物相为 γ-Ni 固溶体和 Ni3Si 陶瓷相。Co 基涂层主要由 γ-Co 固溶体和 Cr7C3陶瓷相构成。Ni 基过渡层的添加抑制了基材中 C 元素扩散，降低了结合界面处白口化趋势。由于 Cr7C3陶瓷相的强化作用，Co 基涂层的显微硬度为球墨铸铁基材的 2.1 倍。与球墨铸铁基材相比，当温度高于 200 ℃时， Co 基涂层在与 Si3N4配副对磨时表现出较低的平均摩擦因数与磨损率。在中低温条件下 Co 基涂层与 Si3N4 配副对磨时的磨损机制为黏着磨损与磨粒磨损，高温条件下的磨损机制为形成连续光滑的氧化层起到减摩抗磨的作用。Co 基涂层表现出更高的自腐蚀电位(-362.36 mV)和更低的自腐蚀电流密度(13.95 nA·cm-2 )。所制备的 Ni-Co 复合涂层能有效提高球墨铸铁表面的高温摩擦学性能和耐腐蚀性能，在发动机领域具有较好的应用前景。 |
| 关键词: 激光熔覆 球墨铸铁 Ni-Co 复合涂层 高温摩擦磨损 耐腐蚀性能 |
| DOI：10.11933/j.issn.1007-9289.20211029002 |
| 分类号:TG174 |
| 基金项目: |
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| Corrosion Resistance and Elevated-temperature Wear Properties of Laser Cladding Ni-Co Composite Coating on Ductile Cast Iron |
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LU Shisheng1,2, ZHOU Jiansong1,2, WANG Lingqian1, LIANG Jun1,2
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1.Key Laboratory of Science and Technology on Wear and Protection of Materials,Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 , China;2.Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences,Beijing 100049 , China
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| Abstract: |
| In order to reduce the content of chilled structure during laser cladding and improve the elevated-temperature tribological properties and corrosion resistance of ductile cast iron, the laser cladded Co-based coating is successfully prepared on the surface of ductile cast iron by adding Ni-based transition layer. The phase composition and microstructures of different layers are characterized by XRD, SEM, EDS. The friction and wear properties of the Co-based coating and ductile cast iron at different temperatures are evaluated utilizing elevated-temperature tribometer and the main wear mechanism of Co-based coating is analyzed. The corrosion resistance of the Co-based coating and ductile cast iron are examined by electrochemical workstation. Results show that the Ni-based transition layer contains γ-Ni solid solution and Ni3Si ceramic phase, Co-based coating is composed of γ-Co solid solution and Cr7C3 ceramic phase. The fabrication of Ni-based transition layer could restrain the diffusion of C element in substrate and control the content of chilled structure at the interface between coating and substrate. Due to the strengthening of Cr7C3 ceramic phase, the microhardness of Co-based coating is 2.1 times higher than that of the ductile cast iron. When the test temperature is higher than 200 ℃, the Co-based coating has lower mean friction factor and wear rate compared with ductile cast iron. When the Co-based coating is rubbed with the Si3N4 counterpart, the wear mechanism of Co-based coating at medium-low temperature is adhesive wear and abrasive wear, and exhibits superior antiwear and friction-reducing behavior due to the formation of the continuous and smooth oxide layer at high temperature. The Co-based coating has higher self-corrosion potential (-362.36 mV) and lower self-corrosion current density (13.95 nA·cm-2 ). The results indicate that the laser cladded Ni-Co composite coating can effectively improve the high-temperature tribological properties and corrosion resistance of ductile cast iron, which has a good application prospect in the field of engine. |
| Key words: laser cladding ductile cast iron Ni-Co composite coating elevated-temperature wear resistance corrosion resistance |
