Lazov, Lyubomir

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Preferred name
Lazov, Lyubomir
Official Name
Lazov, Lyubomir
Alternative Name
Lyubomir Lazov
Lazov, Lyubomir Kostadimov
Main Affiliation
Email
lyubomir.lazov@rta.lv
Scopus Author ID
55384203700
Researcher ID
E-6011-2012

Research Output

Now showing 1 - 5 of 5
  • Publication
    Modification of Aluminum 1050 and 2219 Alloys Using CuBr Nanosecond Laser for Hydrophobic and Hydrophilic Properties
    (2023)
    Antons, Pacejs 
    ;
    Emil Yankov
    ;
    Adijāns, Imants 
    ;
    Teirumnieks, Edmunds 
    ;
    Lazov, Lyubomir 
    This study investigates the use of a CuBr vapor nanosecond laser with a 510 nm/578.2 nm wavelength for the surface treatment of 1050 aluminum and 2219 aluminum alloys. Laser-induced periodic surface structuring was used to optimize processing parameters to achieve hydrophobic and hydrophilic properties on the surface. The wetting properties were measured and the roughness results (Ra, Rz, Rq) evaluated. Prior to and after laser treatment, surface wetting and roughness changes were investigated. The wetting study showed that the maximum contact angle between a droplet of deionized water and the treated surface can be reached between more than 140 degrees and less than 10 degrees, which, respectively, is a superhydrophobic and superhydrophilic surface. Compared with the untreated surface, wetting increased by more than 2 times and decreased by more than 8 times. Overall, experiments show the dependence of wetting properties on laser input parameters such as scan speed and scan line distance with different delivered energy amounts. This study demonstrates the possibility of laser parameter optimizations which do not require auxiliary gases and additional processing of the resulting surfaces to obtain different wetting properties on the surface. The findings described in this article suggest that the CuBr laser surface treatment method is a promising method for industrial applications where surfaces with special wetting and roughness properties are required, for example, the laser marking of the serial number of parts used in wet environments such as aerospace, shipbuilding, and defense industries.
  • Publication
    Effect of Laser Marking Speed, Power and Pitch on Hardness and Roughness of Aisi 304l
    (2023)
    Lazov, Lyubomir 
    ;
    Teirumnieks, Edmunds 
    ;
    Emil Yankov
    ;
    Nikolay Angelov
    ;
    Adijāns, Imants 
    ;
    Antons, Pacejs 
    In this study, an experiment was conducted to change the technological properties of the surface by infra-red laser marking. The influence of power, speed and raster step was investigated. These parameters during laser marking of AISI 304L steel have a significant change on the microhardness and surface roughness. It was found that high stiffness is achieved at higher powers and small pitch. An analysis of the results showed that as the raster step increases, the roughness of the marked sample decreases. The influence of linear energy density and overlap factor on the process was also investigated. The microhardness of the treated surfaces increases with an increase in the linear energy density and the overlap coefficient, and in the first case the dependence is almost linear, and in the second - non-linear.
  • Publication
    Investigation of the influence of the processing speed and the linear pulse density of the laser surface texturing process
    (2023)
    Adijāns, Imants 
    ;
    Lazov, Lyubomir 
    ;
    Ilieva, Mariana
    ;
    Plamenova Nikolova, Maria
    Fine-tuning laser parameters is necessary to achieve the desired quality of the process of laser surface texturing. This requires a set of experiments to assess the influence of the main process parameters on the quality of the surface of a treated alloy. By varying the laser parameters, different laser-material interactions, such as heating, melting, or evaporation can be observed. This study analyzes the influence of two interrelated processing parameters in laser surface texturing – the speed of beam motion on the surface on the one hand, and, on the other, the linear pulse density. They ultimately have a direct impact on the resulting microstructure, hydrophilicity, and electrochemical properties of austenitic steel (AISI 304). By adjusting the pulse repetition rate of a 1064-nm fiber laser from 500 kHz to 1000 kHz at a constant speed of 100 mm/s, the surface wettability changes from hydrophobicity to hydrophilicity. All surfaces treated with laser scanning speeds varying from 20 mm/s to 200 mm/s at a constant rate of 500 kHz are hydrophobic. As a result, the changed ability to repel liquids alters the corrosion properties of the steel in a 0.5 M H2SO4 solution. The results allow one to distinguish ranges of laser-beam parameters that could be useful in selecting certain properties of the stainless-steel surface layer.
  • Publication
    Investigation of the change in wettability properties and corrosion behavior of AISI 304 after laser surface texturing
    (2023)
    Adijāns, Imants 
    ;
    Lazov, Lyubomir 
    ;
    Ilieva, Mariana
    ;
    Plamenova Nikolova, Maria
    Stainless steel is a widely used material in industry, architecture, and medical instruments. However, after various thermal processing of stainless steels, chromium carbides can be formed, which locally depletes the chromium available to form a passive film and reduces the corrosion performance. Laser surface treatment can change the surface chemistry of the steel and improve some electrochemical characteristics. However, these characteristics are influenced by the laser power, pulse width, distance between the lines, scanning speed, etc., which all change the surface chemistry and characteristics of laser surface texturing. Simultaneously, the ability to repel liquids that cause corrosion actions could combine to enhance corrosion performance. Since the wettability of a solid surface depends both on its topography and chemical nature, the micro structuring of an austenitic steel surface is an effective way of fabricating hydrophobic or super hydrophobic corrosion-resistant surfaces. For this reason, this study discusses the effect of laser power in the impact zone and the distance between raster lines on the microstructure, wettability, and corrosion resistance of austenitic steel (AISI 304) when exposed to nanosecond fiber laser radiation. The results indicate that parameter-controlled micro structuring can be used to form both hydrophilic and hydrophobic surfaces with different electrochemical performances.
  • Publication
    Investigation of Surface Structure in the Laser Marking Process as a Function of Speed and Raster Step
    (2023)
    Emil Yankov
    ;
    Lazov, Lyubomir 
    ;
    Teirumnieks, Edmunds 
    ;
    Nikolay Angelov
    ;
    Adijāns, Imants 
    ;
    Antons, Pacejs 
    In this research, an experiment was conducted to change the technological properties of the surface by laser marking. The influence of the speed v of 50 mm/s, 75 mm/s and 100 mm/s and the raster step Δx from 20 µm to 80 µm at a constant average power P = 19.2 W and pulse duration τ = 4 ns was investigated. These parameters during the laser marking of AISI 304L steel have a significant change in microhardness and surface roughness. High hardness was found to be achieved at higher powers and small pitch. Analysis of the results showed that as the raster step increases, the roughness of the marked sample decreases. The effect of linear energy density and overlap factor on the process was also investigated. The microhardness of the machined surfaces increases with an increase in the linear energy density and the overlap coefficient, in the first case the dependence is almost linear, and in the second - nonlinear. Varying the marking speed and raster pitch in laser surface texturing of AISI 304L steel has a significant effect on the surface hardness and roughness, changing HV from 260 HV to 766.5 HV and Ra from 1.75 µm to 4.3 µm, respectively, which are the subject of the present analysis. research.