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Lazov, Lyubomir
Preferred name
Lazov, Lyubomir
Official Name
Lazov, Lyubomir
Alternative Name
Lyubomir Lazov
Lazov, Lyubomir Kostadimov
Email
lyubomir.lazov@rta.lv
Scopus Author ID
55384203700
Researcher ID
E-6011-2012
Research Output
Now showing 1 - 10 of 11
- PublicationModification of Aluminum 1050 and 2219 Alloys Using CuBr Nanosecond Laser for Hydrophobic and Hydrophilic Properties(2023)
; ; ; 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. - PublicationEffect of Laser Marking Speed, Power and Pitch on Hardness and Roughness of Aisi 304l(2023)
; ; ; 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. - PublicationInvestigation of Surface Structure in the Laser Marking Process as a Function of Speed and Raster Step(2023)
; ; ; 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. - PublicationCOLOR MARKING OF STAINLESS STEEL AND TITANIUM WITH THE LASER OXIDATION METHOD(2023)
; ; Marking of metal products is essential in many industrial processes. It is mandatory for the finished products according to regulations of the European and world legislation. Traditional marking usually creates contrasting symbols that can easily be erased and forged.In recent years, a new method for product identification has appeared - color marking. One of the advantages of this method is that it is difficult to counterfeit. This article aims to present the progress of color marking technology on two types of materials. Three groups of factors have been analyzed: the laser source; the technological process; material properties. Their role in obtaining a specific color marking on Ti and AISI 304 is shown. The results are presented in tables. Each color can be repeated only with strict observance of the three groups of factors. - PublicationInvestigation of the Change in Roughness and Microhardness during Laser Surface Texturing of Copper Samples by Changing the Process Parameters(2023)
; - PublicationModification of the roughness of 304 stainless steel by laser surface texturing (LST)(2023)
; ; Scopus© Citations 3 - PublicationInvestigation of the Influence of Some Parameters on the Process of Color Laser Marking(2023)
; ; Nikolay AngelovThe research and development of laser marking technology offers numerous advantages and applications in a variety of industries, from manufacturing and electronics to healthcare and beyond. In industries such as aerospace and automotive, where components must adhere to strict regulatory standards, laser marking can provide the necessary traceability and compliance. Investing in its research and development improves precision, efficiency and innovation, ultimately contributing to advancements in various sectors and driving economic growth.For this purpose, various surface treatment methods are being studied, including laser marking. As can be seen from our previous studies and those of other authors, laser marking of steel surfaces is a complex process and depends on the complex relationships between a number of technological parameters. In this study, we focus on the influence of four of them (parameters: processing speed, laser pulse frequency, pitch between raster lines during laser processing and energy density). During the experiments, the raster step was varied in the range of 20 µm to 80 µm, the velocity was in the range of 25 mm/s to 125 mm/s, and the density was in the range of 5.82 J/mm2 to 29.12 J/mm2. The experiments were done for three frequencies - 20 kHz, 50 kHz and 100 kHz. All these intervals can be realized in the real production. The change of the four investigated parameters was analyzed in relation to the obtained roughness in the processing zone as a function of these four technological parameters and was compared with the corresponding color coordinates of the obtained color markings in these zones. It has been proven that each specific color is associated with surface structural changes as a result of the interaction between laser radiation with a certain laser energy density and the processed material. The present study is a small contribution to the topic of laser color marking of various materials, enabling the production of new surface properties. - PublicationRESEARCHING THE PROCESS OF LASER STRUCTURING OF THE SURFACE OF ALUMINUM(2023)
; In this scientific study, the ability to modify the surface using nanosecond 1064 nm fiber laser by controlling the speed and scanning line step in the marking process was demonstrated. An experimental matrix for laser marking was developed, consisting of 8 columns for marking line step and 5 rows for marking speed. The laser marked surfaces were measured using a laser scanning microscope and compared with the surface as supplied. From the obtained deviations of roughness Ra, Rz and Rq as a function of marking speed and marking line step, graphical dependencies were constructed for comparative analysis. The modified roughness is also compared with the roughness as supplied. Within this research the effect of laser treatment on the hydrophilicity/hydrophobicity of the surface was studied as well. Plots of dependences of the contact angle CA, the marking line step Δx and the overlap coefficient Ksoc are plotted. - PublicationINVESTIGATION OF THE INFLUENCE OF TECHNOLOGICAL PARAMETERS OF LASER MARKING ON THE DEGREE OF CONTRAST(2023)
; ; In modern production, each finished product entering the market is identified by a special marking. Each mark must meet requirements such as good coding, easy to see, easy to read by certain readers, stable over time, etc. In the present casting, laser marking of the C75 steel was carried out with a fiber laser with an average power of P = 30 W and a wavelength of λ = 1064 nm. For semi-contrast marking, marking speeds from 100 mm/s to 700 mm/s, average power from 10 to 30 W, raster pitch from 20 µm to 60 µm, scanning frequency from 20 kHz to 150 kHz were investigated as constant parameters are the pulse duration τ =100 ns, number of repetitions N = 1 and defocus Δ f = 0 mm. The influence of the changing parameters on the contrast was established, and experimental dependences were constructed. The achieved research results show that to obtain a high contrast mark, the average power should be above 20 W, the scanning speed up to 300 mm/s, the scanning frequency up to 50 kHz and the raster pitch up to 40 µm. - PublicationANALYSING THE INFLUENCE OF TECHNOLOGICAL PARAMETERS ON THE PROCESS OF LASER MARKING OF SURFACE OF ANODISED ALUMINIUM SAMPLES(2023)
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