| 摘要: |
| 为提高 NiCr-Cr3C2-BaF2·CaF2 涂层高温耐摩擦磨损性能，减少热喷涂过程中润滑相 BaF2·CaF2 火焰烧蚀，采用溶胶凝胶方法将 BaF2·CaF2 粉体以弥散形式包覆于抗烧蚀陶瓷相 ZrO2 内，形成 ZrO2-BaF2·CaF2 抗烧蚀包覆型粉体，将粉体与 NiCr-Cr3C2 混合后爆炸喷涂以提高涂层内 BaF2·CaF2含量，并表征涂层微观组织和高温耐磨损性能。结果表明：ZrO2包覆型粉体中 BaF2·CaF2呈弥散式分布，制备的 NiCr-Cr3C2-ZrO2-BaF2·CaF2涂层相比传统 NiCr-Cr3C2-BaF2·CaF2涂层，Ca、Ba 元素含量均提升 1 倍以上，两涂层显微硬度分别为 1 041 HV 和 690 HV，这说明 ZrO2陶瓷包覆能有效减少 BaF2·CaF2在喷涂过程中的高温烧蚀，且大幅提升了涂层硬度。高温摩擦磨损试验结果显示，NiCr-Cr3C2-ZrO2-BaF2·CaF2 涂层在 600 ℃、 700 ℃和 800 ℃时的平均摩擦因数分别为 0.25、0.17 和 0.18，与 NiCr-Cr3C2-BaF2·CaF2涂层相比分别降低了 16.7%、39.3% 和 5.3%；NiCr-Cr3C2-ZrO2-BaF2·CaF2涂层磨损率为 5.47×10-6 mm3 ·N-1 ·m-1 ，较 NiCr-Cr3C2-BaF2·CaF2涂层降低了 38.6%。 对磨球表面的微观表征显示，涂层中润滑相含量提升使 NiCr-Cr3C2-ZrO2-BaF2·CaF2 涂层在对磨球表面形成更为完整的润滑转移膜，这将有利于涂层的高温润滑性、稳定性和耐磨损性能。研究结果对热喷涂粉体中易烧蚀物相的热防护和高温自润滑耐磨涂层性能的提升具有借鉴意义。 |
| 关键词: 溶胶凝胶法 抗烧蚀包覆型粉体 高温自润滑耐磨涂层 摩擦磨损性能 |
| DOI：10.11933/j.issn.1007-9289.20211104002 |
| 分类号:TG174 |
| 基金项目:国家科技重大专项(2017-Ⅶ-0013-0110，J2019-Ⅶ-0015-0155)；国家自然科学基金(51905033)资助项目 |
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| High Temperature Tribological Properties of NiCr-Cr3C2-ZrO2-BaF2·CaF2 Coating |
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QI Bin1, YU Haibo1, LIANG Shuaishuai1, LI Jiang1, CHEN Haosheng2
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1.School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083 , China;2.State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 , China
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| Abstract: |
| Aiming to improve the friction and wear resistance of NiCr-Cr3C2-BaF2·CaF2 coating at high temperature and reduce the burn out of the self-lubricating component BaF2·CaF2 during thermal spraying, the sol-gel method is used to disperse the BaF2·CaF2 powder in ZrO2 microspheres. Then, the ZrO2-BaF2·CaF2 powder is mixed with the NiCr-Cr3C2 powder and then sprayed by a detonation gun to prepare coating samples. The microstructure, high-temperature friction and wear resistance of the coatings are studied. Results show that: BaF2 · CaF2 powder can homogeneously disperse in ZrO2 coated powder. Comparing the NiCr-Cr3C2-BaF2·CaF2 coating with the present NiCr-Cr3C2-ZrO2-BaF2·CaF2 coating, the elements of Ca and Ba in the latter are increased by more than one times, and the microhardness of the two coatings is 690 HV and 1041 HV, respectively. Therefore, it can be concluded that the ZrO2 coating can effectively reduce BaF2·CaF2 ablation during the spraying process and enormously improve the hardness of the coating. The average friction factor of NiCr-Cr3C2-ZrO2-BaF2·CaF2 coating is 0.25, 0.17 and 0.18 at 600 ℃, 700 ℃ and 800 ℃, respectively. Compared with the NiCr-Cr3C2-BaF2·CaF2 coating, the friction factor is reduced by 16.7%, 39.3% and 5.3% at 600 ℃ , 700 ℃ and 800 ℃ , respectively. The wear rate of NiCr-Cr3C2-ZrO2-BaF2 · CaF2 coating is 5.47×10-6 mm3 ·N-1 ·m-1 , which is 38.6% lower than that of NiCr-Cr3C2-BaF2·CaF2 coating. The microscopic characterization of the worn surface of the grinding ball shows that the increment of the lubricating phase in the coating makes the NiCr-Cr3C2-ZrO2-BaF2·CaF2 coating form a broader lubricating transfer film on the surface of the grinding ball, which will benefit the high-temperature lubricity, stability and wear resistance of the coating. The results can be used as a reference for the thermal protection of ablation phase in thermal spraying powder and the improvement of the performance of high temperature self-lubricating wear-resistant coating. |
| Key words: sol-gel method anti-ablation composite powder high temperature self-lubricating wear-resistant coating friction properties |
