Effect of chromium coating roughness and thickness on interfacial heat transfer behaviour of sub-rapid solidification process

ABSTRACT

The comparisons of wear resistance and heat transfer behaviours of chromium and brass were conducted. The effects of different values of chromium coating average roughness (1.240, 4.576, 7.388, 9.323 μm) and thickness (15, 35, 55 μm) on the interfacial heat transfer behaviours were investigated with a novel droplet solidification technique. The results revealed that, compared with the brass, the chromium material has a significant improvement in the Vickers hardness and wear performance and a reduction of 25 percent interfacial heat transfer rate. Moreover, with the increase of the coating average roughness from 1.240 to 7.388 μm, the maximum heat flux between molten steel and cooling substrate decreases from 8.27 to 5.56 MW/m² due to the enlargement of the air gap. As the coating average roughness further increases to 9.323 μm, the maximum heat flux increases to 6.50 MW/m² because of the increasing contact area between molten steel and the cooling substrate. In addition, the maximum heat flux was reduced from 8.47 to 5.87 MW/m², considering the enhancement of interfacial thermal resistance when the coating thickness increases from 15 to 55 μm. The results obtained have important implications for heat transfer control of the strip casting process by adjusting the coating average roughness and thickness.

KEYWORDS:

• Strip casting
• chromium coating
• interfacial heat transfer behaviour
• coating average roughness
• coating thickness

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The financial support for this work from the National Natural Science Foundation of China (52274342, 52130408) and the Postgraduate Scientific Research Innovation Project of Hunan Province(CX20220099) are gratefully acknowledged.