Nanosecond Pulse Fiber Laser Blackening of Aluminum Alloy With Alumina Surface

Abstract

Blackening aluminum alloy with alumina surface now can be achieved in a cost-effective way with a nanosecond pulse fiber laser at 1064-nm wavelength, putting aside the traditional bulky, expensive femtosecond or picosecond pulse lasers. The surface blackening effect is numerically studied by the International Commission on Illumination L* value and it is found that the laser power fluence needs a proper control to obtain the shining black color effect. The surface profile and optical properties of the surfaces with or without laser treatment are analyzed. The nanostructures and microstructures layer formed beneath the alumina surface is discovered, and it is suggested to be the cause for the structural black color. This letter provides progress to a broader understanding on the nanosecond laser-induced blackening of Al with alumina surface. This nanosecond pulse fiber laser-induced blackening technique is useful for light power sensing, antireflective surface, and surface decoration applications.