Abstract
The work aims to prepare a protective coating which is resistant to high temperature oxidation and can be used in high temperature oxygen-enriched environment. With MoSi2-Al2O3 agglomerated and sintered powder as raw material for spraying, high temperature oxidation resistant MoSi2-Al2O3 coatings was prepared on the surface of 310S stainless steel by adopting process of flame spraying and plasma spraying. SEM, EDS, XRD and surface roughness tester were used to analyze structure of the coatings, bonding strength of the coatings was tested in tensile method, and high temperature oxidation resistance of the coatings was tested by performing high temperature oxidation experiment. Plasma spraying coating was superior to flame spraying coating in terms of powder melting degree, the coating exhibited more compact stacked structure, and distribution of Si, O element was more uniform. Bonding strength of plasma sprayed coating was 24.25 MPa, nearly 68% higher than that of flame sprayed coating. After high temperature oxidation test at 1200 ℃, the flame sprayed coating was subject to pulverization, severe oxidation and spalling while the plasma sprayed coating was not subject to pulverization (with intact coating structure). Coating pulverization could be prevented effectively in the process of high temperature oxidization due to compact structure of the plasma sprayed coating, uniformly distributed Si element was more likely to generate SiO2 and repair coating cracks in the process of coating oxidization, which prevented oxygen atoms from diffusing toward coating interior. Moreover, the coating exhibited excellent high temperature oxidization resistance. Plasma spraying technology can be used to prepare MoSi2-Al2O3 coatings exhibiting better microstructure, bonding strength and high temperature oxidation on the surface of 310S stainless steel.
Key words
MoSi2-Al2O3 coating; agglomerated and sintered powder; flame spraying; plasma spraying; bonding strength; high temperature oxidation resistance
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HUO Da, LI Wen-sheng, FENG Li, HU Chun-xia, HU Wei.
Effects of Spraying Process on Microstructure and Properties of MoSi2-Al2O3 Coating[J]. Surface Technology. 2018, 47(4): 267-273
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Funding
Supported by International Science and Technology Cooperation Program of China (2015DFR51090), National Natural Science Foundation of China (51674130) and Natural Science Foundation of Gansu Province (1508RJZA006)