Guo Wenmin, Zhang Honglin, Zhao Shan, Ding Zhibing, Liu Bin, Li Wenjuan, Xu Huanhuan, Liu Huiyuan
State Key Lab of Powder Metallurgy, Central South University, Changsha 410083, China.
College of Mechanical and Energy Engineering, Shaoyang University, Shaoyang 422000, China.
Materials (Basel). 2021 Nov 22;14(22):7093. doi: 10.3390/ma14227093.
The oxidation of the metal powder during the thermal spraying process usually leads to significant deterioration of the microstructure and performance of the coating. In order to isolate the metal powder from oxygen during the spraying process, the CoNiCrAlY-AlO core-shell structured powder with AlO as the shell was designed in this study. The influence of the core-shell structured powder on the microstructure and corrosion resistance of the HVOF coating has been studied in detail. The results show that the temperature field of the molten CoNiCrAlY powder during the spraying process is significantly changed by the AlO shell. The poor deformability of the CoNiCrAlY-AlO droplets leads to an increase in the porosity and unmelted particles of the coating. In addition, the significant difference is that the coating also maintains a high content of β-NiAl phase. The lower oxide content in the CoNiCrAlY-AlO coating indicates that the core-shell structured powder significantly inhibits the oxidation of the CoNiCrAlY core powder during the spraying process. The CoNiCrAlY-AlO coating exhibits high corrosion potential, passive film resistance, charge transfer resistance, and low corrosion current density in 3.5 wt.% NaCl solution, indicating that the coating has excellent corrosion resistance.
热喷涂过程中金属粉末的氧化通常会导致涂层的微观结构和性能显著劣化。为了在喷涂过程中将金属粉末与氧气隔离，本研究设计了以AlO为壳层的CoNiCrAlY-AlO核壳结构粉末。详细研究了核壳结构粉末对HVOF涂层微观结构和耐蚀性的影响。结果表明，AlO壳层显著改变了喷涂过程中熔融CoNiCrAlY粉末的温度场。CoNiCrAlY-AlO液滴的变形性差导致涂层孔隙率和未熔颗粒增加。此外，显著的差异在于涂层还保持了较高含量的β-NiAl相。CoNiCrAlY-AlO涂层中较低的氧化物含量表明核壳结构粉末在喷涂过程中显著抑制了CoNiCrAlY核粉的氧化。CoNiCrAlY-AlO涂层在3.5 wt.% NaCl溶液中表现出高腐蚀电位、钝化膜电阻、电荷转移电阻和低腐蚀电流密度，表明该涂层具有优异的耐蚀性。
