Influence of Laser Colour Marking on the Corrosion Properties of Low Alloyed Ti

Abstract

In the field of surface treatment, laser colour marking can be used to produce coloured marks on the surfaces of metals. Laser colour markings can be applied to various materials, but on titanium alloys a wide spectra of vivid colours can be achieved. This study presents an analysis of the corrosion properties of laser treated surfaces that were exposed to aggressive environments. Different samples were prepared with laser light of various power intensities and processing speeds. The samples were prepared on low alloyed Ti. Electrochemical, spectroscopic and microstructural analyses were conducted in order to study the properties of the laser treated surfaces. Corrosion testing showed different effects of laser power and production speed on the properties of the laser treated surfaces. It was shown that a high intensity and slow processing rate affect the surfaces by forming oxides that are relatively stable in a corrosive environment of 0.1 M NaCl. Spectroscopic investigations including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses showed the differences in chemical structure of the surface layer formed after laser treatment. Similarly, microstructural investigations showed different effects on the surface and sub-surface layer of the laser treated samples. advantages of laser induced oxidation are that the process is non-contact and that the marking of smaller surfaces can be made fast at relatively low cost. The produced markings are very sharp, reproducible and precise. Another benefit is that the process enables flexible change of marking colours on the fly with respect to laser processing parameters [6,[13][14][15][16].Titanium and its alloys have several specific properties, like good strength to weight ratio, high strength, good chemical stability, high temperature stability, biocompatibility, corrosion resistance and resistance to fatigue and wear, and can be heat treated or surface treated in order to achieve particular hardness and strength [11,26].Laser induced oxidation of metals is a gaseous high-temperature corrosion process, where thin layers of oxides or other more complex oxidation formations are formed. With this process, different colours can be produced on the titanium surface. During laser oxidation, titanium oxides are formed at the surface if the marking is carried out in an oxidative atmosphere. Titanium oxides are not expensive, biocompatible, non-toxic and mechanically and chemically stable [16]. On the surfaces, there are thin layers present in the form of anatase, brookite, rutile or in the amorphous phase [6,13,16]. In the white light spectrum, they are highly transparent and exhibit a wide spectrum of vivid colours as a result of the interference between white light and the borders between different phases. The obtained colours depend on the thickness of the oxide layer, refractive index and the interference between light and incidence angle [6,13,15,27]. There are many laser parameters, such as pulse duration, pulse repetition rate, pulse en...

Bioactive Coating on Titanium Dental Implants for Improved Anticorrosion Protection: A Combined Experimental and Theoretical Study

“…Since the artificial saliva solution represents an aggressive medium, a high amount of chloride ions affects the oxide film properties and accelerates the titanium corrosion (degradation) process during a prolonged immersion period [51]. Calculated parameters, especially R 1 values, indicate that the contribution of the outer layer of the oxide film to the electrochemical behaviour is rather imperceptible, and the overall EIS response is dominated by the inner barrier layer of the oxide film, which is in accordance with previously reported results [43,44].…”

“…The EIS data of the unmodified Ti-implant (Ti-implant/oxide film/artificial saliva interface) were fitted to the EEC with two time constants (Figure 5c) and the parameter values are presented in Table 2. The EEC used is commonly applied to analyze impedance results of Ti and Ti-alloys covered with a bi-layer structure of oxide film [22,[43][44][45][46][47][48]. The high/middle frequency time constant (R 1 -CPE 1 ) describes the characteristics of the outer porous layer of the oxide film.…”

“…R 1 represents the resistance and CPE 1 the capacitance of the outer layer. The low frequency time constant (R 2 -CPE 2 ) is related to the inner barrier layer of the oxide film, predominately containing titanium(IV) oxide [1,44,49]. R 2 represents the resistance and CPE 2 the capacitance of the barrier layer.…”

Mechanical and Corrosion Properties of Laser Surface-Treated Ti13Nb13Zr Alloy with MWCNTs Coatings

“…Modern laser technologies have been used in the modification of biocompatible materials such as titanium. These modification methods allow melting and remelting [51][52][53], alloying [17,44,54], direct laser deposition [55], texturing and marking [56,57] and laser ablation [58]. Interest in laser methods is increasing due to their numerous advantages including the possibility of local only processing.…”

Nanosecond Pulsed Laser Irradiation of Titanium Alloy Substrate: Effects of Periodic Patterned Topography on the Optical Properties of Colorizing Surfaces

“…Under this thickness, the laser treatment for this purpose may not be an effective method. On the other hand, mainly due to the cooling processes, in rare cases, the existence of micro-cracks may occur ( Figure 6), according to [37]. Crack growth over the track surface is caused by the solidification process of the vaporized titanium alloy and the oxidation that takes place during the beam displacement.…”