A study on HVOF coating of WC-metal powder on super alloy In718 of magnetic bearing shaft material of turbo-blower

Autor: Tong Yul Cho, Jae Hong Yoon, Hui Gon Chun, Yoon Kon Joo
Rok vydání: 2014
Předmět:
Zdroj: International Journal of Precision Engineering and Manufacturing. 15:1479-1484
ISSN: 2005-4602
2234-7593
DOI: 10.1007/s12541-014-0494-7
Popis: HVOF thermal spray coating of micron-sized WC-metal powder onto Inconel718 surface was carried out for the durability improvement of magnetic shaft of turbo-blower. Porous coating of porosity 2.2±0.4% was formed, but the surface properties were improved, such as surface hardness from 400±10 Hv (In718) to 1250±50 Hv (coating), friction coefficient from 0.46±0.06 to 0.32±0.04 at surface temperature 25°C and from 0.38±0.04 to 0.28±0.04 at surface temperature 450°C. Wear resistance improved decreasing the wear trace by coating. Corrosion resistance improved by coating in 3.5% NaCl solution (sea water) and in acid, but it worsened in base. The coating was CO2 laser heat-treated for further improvement of the properties of the coating. By laser heating of 0.6 second with power density 20 W/mm2, coating thickness was decreased, porosity decreased more than five times from 2.2±0.4% to 0.4±0.1%, the surface hardness increased to 1830±100 Hv the interface (coating/substrate) was compacted, and elements diffused from both coating and substrate inconel718 to interface, forming metal rich buffer zone(interface) and enhancing the adhesion of coating. For the improvement of durability of the magnetic shaft, HVOF WC-metal power coating and laser heat-treatment are recommended.
Databáze: OpenAIRE
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