The influence of process parameters on the laser-induced coloring of titanium

Abstract

This paper presents the results of the measurements and analysis of the influence of laser process parameters on the color obtained. The study was conducted for titanium (Grade 2) using a commercially available industrial pulsed fiber laser. It was determined how a variety of different laser process parameters, such as laser power, the scanning speed of the material, the temperature of the material, the size of the marked area, and the position of the sample, relative to both the focal plane and the center of the working field of the system, affect the repeatability of the colors created. For an objective assessment of color changes, an optical spectrometer and the CIE color difference parameter E * ab were used. Our paper explains why the tolerance of process parameters highly depends on the specific color. Additionally, a comparison of the results for titanium with those obtained for stainless steel in a previous study is presented. Based on this analysis, a number of necessary modifications are proposed to laser systems commonly used for monochrome marking in order to improve repeatability in color marking.

Development of complete color palette based on spectrophotometric measurements of steel oxidation results for enhancement of color laser marking technology

“…8a there is the reflectance spectrum of the untreated stainless steel surface as a function of the light incidence angle on the sample (from 0° to 70°). The graph shows that the A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 9 spectrum slightly varies with the incidence angle change. Fig.…”

“…The colors were generated at corresponding regimes of laser treatment. On base of color coordinates of model and generated colors the criterion of color reproduction accuracy ΔE ab was calculated according to [9,12]. It had a value less than 5; therefore, generated and model colors are indistinguishable by human eye.…”

“…It was implemented through the formation of oxide films using solid-state and fiber lasers with several wavelengths: 355 nm [4], 532 nm [5], 1064 nm [3,[6][7][8][9][10]; the composition of the films was found. These oxide films demonstrated resistance to external influences [9]. Available colors and the sequence of their formation vary from metal to metal.…”

Characterisation of coloured TiO /Ti/glass systems

“…The expressive colour of the sample can be obtained on a titanium plate through the preparation of the titanium oxide layer by means of anodic oxidation [12,13] or laser-induced heating [14,15]. In each of the above-mentioned cases the dielectric film is formed on the surface of metal.…”

“…Previous studies on colours of titanium oxide layers were concerned with the optical properties, microstructure, chemical composition and visual aspects of coatings prepared mostly by anodic oxidation [12,13] and laser-induced titanium dioxide on titanium plate [14,15]. The aim of this work is the study of optical properties and the microstructure of the titanium oxide layer and titanium undercoat formed by the GIMS method and its impact on a colour of samples.…”