Abstract

Effective control of fluid dynamics is of remarkable scientific and practical significance. It is hypothesized that nanoparticles could offer a novel means to control fluid dynamics. In this study, laser melting was used to investigate the feasibility of tuning fluid dynamics by nanoparticles and possibly breaking existing limits of conventional laser processing techniques. Alumina nanoparticles reinforced nickel samples, fabricated through electrocodeposition, were used for laser melting experiments. Since the melt pool surface is controlled by the fluid dynamics, surface topographies were carefully studied to reveal the nanoparticle effect on the fluid dynamics. Characterizations of surface topographies and microstructures of pure Ni and Ni/Al2O3 nanocomposite were carried out before and after laser melting. The surface roughness of the Ni/Al2O3 nanocomposite sample was reduced significantly by laser melting, which broke the existing limit of laser surface polishing of pure Ni. It is believed that the nanoparticles increased the viscosity of the molten metal, thereby enhancing the viscous damping of the capillary oscillations in the melt pool, to produce a much smoother surface. Moreover, the experimental study also revealed that the viscosity enhancement by the nanoparticles effectively suppressed the thermocapillary flows which would introduce artificial asperities on a surface. The experimental results suggest that nanoparticles are effective in controlling melt pool dynamics and overcoming the existing limits of laser processing. The new methodology, fluid dynamics control by nanoparticles, opens a new pathway to enrich liquid based processes for broad applications.

Department(s)

Mechanical and Aerospace Engineering

Keywords and Phrases

Alumina; Capillary flow; Dynamics; Fluid dynamics; Lakes; Liquid metals; Melting; Nanocomposites; Nanoparticles; Nickel; Surface roughness; Surface topography; Viscosity; Alumina Nanoparticle; Broad application; Conventional lasers; Electrocodeposition; Melt pool dynamics; Nanocomposite samples; Nanoparticle effects; Thermocapillary flow; Metal nanoparticles

International Standard Serial Number (ISSN)

0021-8979; 1089-7550

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2015 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Mar 2015

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