Thermohydrodynamics analysis on the mechanism of bump formation in laser texturing

Etsuji Ohmura; Rina Murayama; Isamu Miyamoto

doi:10.1117/12.405751

6 November 2000 Thermohydrodynamics analysis on the mechanism of bump formation in laser texturing

Etsuji Ohmura, Rina Murayama, Isamu Miyamoto

Proceedings Volume 4088, First International Symposium on Laser Precision Microfabrication; (2000) https://doi.org/10.1117/12.405751
Event: First International Symposium on Laser Precision Microfabrication (LPM2000), 2000, Omiya, Saitama, Japan

Abstract

Laser texturing on a hard disk for a computer has been already used practically, but the mechanism of bump formation has not been elucidated yet. The purpose of this study is to elucidate the mechanism of bump formation in laser texturing by thermohydrodynamics analysis. Latent heat of evaporation, movement of gas and liquid interface, evaporation recoil pressure, Marangoni force that depends on temperature gradient and the surface tension are considered. The VOF (Volume of Fluid) method is used for the analysis of behavior of the free surface. Obtained results are as follows : (1) The downward flow is generated in the molten pool by the evaporation recoil pressure, and then it induces the outward flow in the radial direction. (2) After laser irradiation is stopped, the downward flow at the center of the molten pool and the outward flow in the radial direction are kept. Therefore, the center of the molten pool is lowered and the surface rises around the hole, that is, a bump is formed. (3) When the temperature coefficient of surface tension is negative, Marangoni force is most effective to the surface rise when the resolidification starts outside of the bump.

Citation Download Citation

Etsuji Ohmura, Rina Murayama, and Isamu Miyamoto "Thermohydrodynamics analysis on the mechanism of bump formation in laser texturing", Proc. SPIE 4088, First International Symposium on Laser Precision Microfabrication, (6 November 2000); https://doi.org/10.1117/12.405751

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