G. V. Odintsova

Controlled oxide films formation by nanosecond laser pulses for color marking

A technology of laser-induced coloration of metals by surface oxidation is demonstrated. Each color of the oxide film corresponds to a technologic chromacity coefficient, which takes into account the temperature of the sample after exposure by sequence of laser pulses with nanosecond duration and effective time of action. The coefficient can be used for the calculation of laser exposure regimes for the development of a specific color on the metal. A correlation between the composition of the films obtained on the surface of stainless steel AISI 304 and commercial titanium Grade 2 and its color and chromacity coordinates is shown.

Availability of methods of chemical thermodynamics and kinetics for the analysis of chemical transformations on metal surfaces under pulsed laser action

A computational thermodynamic approach to determining the phase-chemical composition of films formed on the surface of metals and alloys under laser oxidation in the normal atmosphere, depending on their bulk composition, laser exposure conditions, and composition of the atmosphere, is suggested. It is demonstrated for the example of a complex alloy (alloyed steel of Russian brand 12X18H10T) subjected to laser heating in air that, among the wide variety of different possible reactions of iron, nickel, or chromium with the components of air (oxygen, nitrogen, carbon, its compounds, atmospheric moisture, etc), only strictly defined reactions can occur. First of all these are metal oxidation processes with the formation of an oxide film whose phase and chemical composition is determined by temperature and heating duration. Simulated results are confirmed by the experimental data provided by energy-dispersive x-ray spectroscopy.

Laser induced multicolor image formation on metal surfaces

Experimental results and theoretical estimations of the color image formation by laser oxidation of steel surface are considered. Method of laser radiation parameters selection to provide desirable color is offered. Influences of diffraction effects to the metal surface color characteristics are analyzed.

Laser decoration of precious metals

A technique for the laser coloration of precious metals is described that is based on the oxidation of a titanium film deposited on the surface of a metal. When laser radiation acts on the film, it is heated and oxidizes. Depending on the radiation parameters, the resulting oxide films have different thicknesses and, due to light interference, they acquire different colors. The visible color of the surface depends on the angle of viewing after imaging. The aim of this work is to identify the color palette of a gold plate’s surface with a thin film of titanium deposited on it. The titanium film is oxidized via fiber laser irradiation with a wavelength of 1.064 μm. Samples of color palettes are examined spectrophotometrically, and the chemical and mechanical stability of the resulting oxide coatings are tested.