| 摘要: |
| MCrAlY 涂层以其优异的高温抗氧化性能和力学性能，成为燃气轮机高温防护部件不可或缺的一部分，但涂层、基体和环境之间的复杂相互作用，使得某些合金元素的单一添加无法满足现有 MCrAlY 涂层的使役要求。采用真空悬浮熔炼法制备块状 NiCoCrAlY 合金，使用 Thermo calc 软件计算掺杂元素后 NiCoCrAlY 合金的相平衡，利用 X 射线衍射仪(XRD)对 NiCoCrAlY 合金进行物相检测，利用扫描电子显微镜(SEM)和电子背散射衍射(EBSD)研究合金的微观结构和晶粒取向， 通过显微硬度、纳米压痕和压缩试验来表征其力学性能。选用优选出的合金成分制备粉体，利用 HVAF 喷涂技术制备涂层试样，与商用 NiCoCrAlY 涂层在相组成、显微组织、力学性能和耐磨性能上做对比研究。结果表明，随着 Hf 含量的增加，合金中晶粒尺寸增大；当 Hf 含量为 1 wt.%时，合金的抗压强度和抗压应力得到提高；Hf 含量为 4 wt.%时，合金具有较高的塑性。 掺杂改性后的 NiCoCrAlYNbMoHfTa 涂层中主相为 β 相；涂层显微硬度显著提高，且有着和商用 NiCoCrAlY 涂层相近的结合强度；相较于商用 NiCoCrAlY 涂层，NiCoCrAlYNbMoHfTa 涂层表现出更加优异的磨损防护性能。对传统的 MCrAlY 材料进行掺杂，探明 Hf 掺杂对 NiCoCrAlY 合金的力学性能影响及强化机制，所制备的涂层具有良好的力学性能和摩擦学性能。 |
| 关键词: NiCoCrAlY 难熔金属掺杂 显微结构 力学性能 HVAF |
| DOI：10.11933/j.issn.1007-9289.20211105001 |
| 分类号:TF815;TG176 |
| 基金项目:国家重点研发资助项目(2018YFB1105800) |
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| Design and Strengthening Mechanism of the Hf-doped NiCoCrAlY Coatings Based on Phase Equilibrium Calculation |
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WANG Xiaoming1, HAN Guofeng1, YIN Yichuan2, ZHU Sheng1
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1.National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072 , China;2.School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 , China
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| Abstract: |
| MCrAlY coating has become an indispensable part of gas turbine high temperature protection components due to its excellent high temperature oxidation resistance and mechanical properties. However, the complex interaction among the coating, the substrate and the environment makes the single addition of some alloying elements unable to meet the service requirements of the existing MCrAlY coatings. The bulk NiCoCrAlY alloys are prepared by vacuum suspension melting. The phase equilibrium of the NiCoCrAlY alloys after doping elements are calculated by thermo Calc software. X-ray diffractometer (XRD) is employed to aid the phase identifications of the NiCoCrAlY alloys. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) utilized to investigate the microstructure and grain orientation of the alloys. The microhardness, nanoindentation and compression tests are conducted to characterize the mechanical properties. In addition, the selected alloy components are selected to prepare powder, and the coating samples are prepared by HVAF spraying technology. The phase composition, microstructure, mechanical properties and wear resistance of commercial NiCoCrAlY coatings are compared and studied. The results show that the increase of Hf content led to the increase of the grain size in the alloy. In addition, when the Hf content is 1 wt.%, the compressive strength and compressive stress of the alloy are improved, and when the Hf content is 4 wt.%, the alloy has higher plasticity. The main phase of the NiCoCrAlYNbMoHfTa coating after doping modification is β phase. The microhardness of the coating is significantly improved, and it has a bonding strength that is very close to that of the commercial NiCoCrAlY coating. In addition, compared to NiCoCrAlY coating, NiCoCrAlYNbMoHfTa coating shows more excellent wear protection. Traditional MCrAlY materials are doped, and the effects of Hf doping on the mechanical properties and strengthening mechanism of NiCoCrAlY alloys are investigated, and the prepared coatings have good mechanical and tribological properties. |
| Key words: NiCoCrAlY Hf-doping microstructure mechanical property HVAF |
