Enhanced Absorptance of 45# Steel by Laser-Induced Periodic Surface Structures (LIPSS)

Tianyu Wang,Hui Kong,Xi Wang,Xiaoquan Sun,Jintian Bian,Xin Li,Lei Wang

doi:10.3390/met10091237

Tianyu Wang, Hui Kong + Show 5 more

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https://doi.org/10.3390/met10091237

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Journal: Metals	Publication Date: Sep 14, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: National University of Defense Technology

Abstract

The absorptance of metals is often low within the visible and near-infrared band at room temperature. Increasing the absorption of metals plays a vital role in reducing energy consumption and production cost. After irradiation by 10 ns linearly polarized pulses with fluence close to the zero-probability damage threshold, the surface of 45# steel samples exhibited four kinds of surface structures in the spot area. The samples’ absorptance is improved by 38% when a high-quality laser-induced surface structure (LIPSS) appears at the spot centre. With the increase of the number of pulses, LIPSS begin to melt down, which will decrease the surface absorptance due to the appearance of damage stripes. The relative absorptance of samples was measured by an integrating sphere system. The paper reports detailed experiments to show that LIPSS can improve samples’ absorptance significantly.

Highlights

In 1965, Birnbaum found a series of periodic stripes on semiconductors after irradiation by linearly polarized long pulses generated by a ruby laser [1]
In order to improve the measurement accuracy of samples’ absorptance, the surface of plates should be covered by a large area of laser-induced periodic surface structures (LIPSS), so unfocused pulses were used
The results showed that the relative absorptance of samples was increased as soon as low spatial frequency LIPSS (LSFL) appeared at the spot centre

Summary

Introduction

In 1965, Birnbaum found a series of periodic stripes on semiconductors after irradiation by linearly polarized long pulses generated by a ruby laser [1]. The stripes were later named laser-induced periodic surface structures (LIPSS). After irradiation near the materials’ ablation threshold [2], LIPSS appear on the surface of samples. LIPSS can be observed on most kinds of solid materials, including metals [3], semiconductors [4], crystals [5], ceramic materials [6], polymers [7], etc. Since LIPSS can change the absorptivity [8], hydrophilicity/hydrophobicity [9,10], colourability [11], modulation coding [12], antimicrobial properties [13] and other properties of materials, they have been an interesting research direction for more than half a century.

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