The Experts below are selected from a list of 1344 Experts worldwide ranked by ideXlab platform
A. Pertek - One of the best experts on this subject based on the ideXlab platform.
-
Laser Surface Modification of boronickelized medium carbon steel
Optics and Laser Technology, 2015Co-Authors: A. Bartkowska, A. Pertek, M Kulka, Leszek KlimekAbstract:Abstract A two-step process was applied to produce the multicomponent boride layers. Boronickelizing consisted of nickel plating and diffusion boriding. Two different methods of heat treatment of boronickelized C45 steel were used: a typical through-hardening, and a Laser Surface Modification with remelting. Microstructure and some mechanical properties of these layers were examined. Microstructural characterization was studied using optical microscope, Scanning Electron Microscope, energy-dispersive X-ray microanalysis, Electron Back-Scatter Diffraction and X-ray diffraction. The Laser Modification improved wear resistance, cohesion as well as low-cycle fatigue of the boronickelized layer. Compressive stresses, occurring after Laser remelting, could be the reason for the advantageous mechanical behavior of the layer.
-
Laser Surface Modification of Borochromizing C45 Steel
Archives of Metallurgy and Materials, 2012Co-Authors: A. Bartkowska, A. Pertek, M. Jankowiak, K. JóźwiakAbstract:Laser Surface Modification of Borochromizing C45 SteelIn this study the test results for borochromized C45 steel after Laser Surface Modification were presented. Influence of Laser heat treatment on the microstructure and microhardness of Surface layer was investigated. The process of borochromizing consisted of chromium plating followed by diffusion boronizing. The Laser heat treatment (LHT) of multiple tracks in the helical line was carried out with CO2Laser beam. The technological Laser TRUMPF TLF 2600 Turbo CO2of the nominal power 2.6 kW was applied. Borochromizing was carried out with Laser power density q = 41.40 kW/cm2and at Laser beam scanning rate v = 0.67 m/min and v = 2.016 m/min. Measurements of microhardness were conducted using the Vickers' method and Zwick 3212 B hardness tester. Microstructure observations were performed by means of an optical microscope Metaval Carl Zeiss Jena and scanning electron microscope Tescan VEGA 5135. After Laser heat treatment with re-melting a three-zone layer was obtained, which included: re-melted zone, heat affected zone and a core. Influence of Laser treatment parameters on thickness of melted zone and microstructure of the Surface layer was tested. The microhardness tested along the axis of track of the Surface layer after Laser Modification was about 800-850 HV. The results of tests showed influence of Laser power density and scanning rate on microstructure and properties of borochromized layers.
-
Laser Surface Modification of carburized and borocarburized 15crni6 steel
Materials Characterization, 2007Co-Authors: M Kulka, A. PertekAbstract:The paper presents the results of Laser heat treatment (LHT) of carburized and borocarburized 15CrNi6 low-carbon steel. Laser tracks were arranged by CO{sub 2} Laser beam as multiple tracks formed in the shape of a helical line. The microstructure and properties of these diffusion layers were compared with those obtained after through-hardening. The microstructure after carburizing and LHT consists of adjacent characteristic zones: re-melted zone (coarse-grained martensite), carburized layer with heat affected zone (fine acicular martensite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest measured microhardness (about 820 HV) was observed in re-melted and heat affected zones. The increase of distance from the Surface was accompanied by a gradual decrease of microhardness up to 400 HV beneath the HAZ and up to 250 HV in the core of steel. The carburized layer after LHT exhibited a higher resistance to frictional wear compared to a carburized layer after through-hardening. The microstructure after borocarburizing and LHT consists of the following characteristic zones: iron borides of Laser-modified morphology (FeB and Fe{sub 2}B), carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest microhardness was obtainedmore » in the iron boride zone. The microhardness of FeB boride extended up to 2200 HV and for the Fe{sub 2}B boride up to about 1300-1600 HV. With increased distance from the Surface, the microhardness gradually decreases to 800 HV in HAZ, 400-450 HV in the carburized layer without heat treatment and to 250 HV in low-carbon substrate. The iron borides after LHT assume a globular shape, which leads to a lower texture and porosity of the borided layers. The increased resistance to friction wear of the borocarburized layers is certified in comparison with the borided layer after conventional heat treatment (through-hardening)« less
-
microstructure and properties of borocarburized 15crni6 steel after Laser Surface Modification
Applied Surface Science, 2004Co-Authors: M Kulka, A. PertekAbstract:Abstract The paper presents the results of Laser heat treatment (LHT) of the borided layers produced on the carburized 15CrNi6 low-carbon steel. The two-step treatment carburizing followed by boriding is termed borocarburizing. Laser tracks were arranged by CO2 Laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of the following zones: iron borides (FeB and Fe2B) of Laser modified morphology, needle-like iron borides, carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). X-ray microanalysis of the Laser modified borocarburized specimen confirmed the presence of the same two types of iron borides (FeB and Fe2B), like those indicated in the as-borided layer. The layer after borocarburizing and LHT has a high microhardness of iron borides, reducing the hardness gradient between the diffusion layer and the substrate in comparison with only borided layer. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided and borocarburized layers after conventional heat treatment. It is probably result of globular iron boride presence after Laser Surface Modification.
-
microstructure and properties of borided 41cr4 steel after Laser Surface Modification with re melting
Applied Surface Science, 2003Co-Authors: M Kulka, A. PertekAbstract:Abstract The paper presents the results of Laser Surface Modification of the borided layers produced on the 41Cr4 medium carbon steel (0.43% C, 1.02% Cr). Laser tracks were arranged by CO2 Laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of three following zones: re-melted zone (MZ) (eutectic mixture of borides and martensite), heat-affected zone (HAZ) (martensite) and the substrate (ferrite and pearlite). XRD scans of the Laser-modified borided specimen confirmed the presence of the same two types of iron borides (FeB and Fe2B), like these indicated in the as-borided layer. After re-solidification in some places iron richer Fe3B phase was additionally formed. The layer after boriding and Laser heat treatment (LHT) has a lower microhardness, than the only borided layer, reducing the hardness gradient between the diffusion layer and the substrate. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided layers after conventional heat treatment.
M Kulka - One of the best experts on this subject based on the ideXlab platform.
-
Laser Surface Modification of boronickelized medium carbon steel
Optics and Laser Technology, 2015Co-Authors: A. Bartkowska, A. Pertek, M Kulka, Leszek KlimekAbstract:Abstract A two-step process was applied to produce the multicomponent boride layers. Boronickelizing consisted of nickel plating and diffusion boriding. Two different methods of heat treatment of boronickelized C45 steel were used: a typical through-hardening, and a Laser Surface Modification with remelting. Microstructure and some mechanical properties of these layers were examined. Microstructural characterization was studied using optical microscope, Scanning Electron Microscope, energy-dispersive X-ray microanalysis, Electron Back-Scatter Diffraction and X-ray diffraction. The Laser Modification improved wear resistance, cohesion as well as low-cycle fatigue of the boronickelized layer. Compressive stresses, occurring after Laser remelting, could be the reason for the advantageous mechanical behavior of the layer.
-
Laser Surface Modification of carburized and borocarburized 15crni6 steel
Materials Characterization, 2007Co-Authors: M Kulka, A. PertekAbstract:The paper presents the results of Laser heat treatment (LHT) of carburized and borocarburized 15CrNi6 low-carbon steel. Laser tracks were arranged by CO{sub 2} Laser beam as multiple tracks formed in the shape of a helical line. The microstructure and properties of these diffusion layers were compared with those obtained after through-hardening. The microstructure after carburizing and LHT consists of adjacent characteristic zones: re-melted zone (coarse-grained martensite), carburized layer with heat affected zone (fine acicular martensite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest measured microhardness (about 820 HV) was observed in re-melted and heat affected zones. The increase of distance from the Surface was accompanied by a gradual decrease of microhardness up to 400 HV beneath the HAZ and up to 250 HV in the core of steel. The carburized layer after LHT exhibited a higher resistance to frictional wear compared to a carburized layer after through-hardening. The microstructure after borocarburizing and LHT consists of the following characteristic zones: iron borides of Laser-modified morphology (FeB and Fe{sub 2}B), carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). The highest microhardness was obtainedmore » in the iron boride zone. The microhardness of FeB boride extended up to 2200 HV and for the Fe{sub 2}B boride up to about 1300-1600 HV. With increased distance from the Surface, the microhardness gradually decreases to 800 HV in HAZ, 400-450 HV in the carburized layer without heat treatment and to 250 HV in low-carbon substrate. The iron borides after LHT assume a globular shape, which leads to a lower texture and porosity of the borided layers. The increased resistance to friction wear of the borocarburized layers is certified in comparison with the borided layer after conventional heat treatment (through-hardening)« less
-
microstructure and properties of borocarburized 15crni6 steel after Laser Surface Modification
Applied Surface Science, 2004Co-Authors: M Kulka, A. PertekAbstract:Abstract The paper presents the results of Laser heat treatment (LHT) of the borided layers produced on the carburized 15CrNi6 low-carbon steel. The two-step treatment carburizing followed by boriding is termed borocarburizing. Laser tracks were arranged by CO2 Laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of the following zones: iron borides (FeB and Fe2B) of Laser modified morphology, needle-like iron borides, carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). X-ray microanalysis of the Laser modified borocarburized specimen confirmed the presence of the same two types of iron borides (FeB and Fe2B), like those indicated in the as-borided layer. The layer after borocarburizing and LHT has a high microhardness of iron borides, reducing the hardness gradient between the diffusion layer and the substrate in comparison with only borided layer. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided and borocarburized layers after conventional heat treatment. It is probably result of globular iron boride presence after Laser Surface Modification.
-
microstructure and properties of borided 41cr4 steel after Laser Surface Modification with re melting
Applied Surface Science, 2003Co-Authors: M Kulka, A. PertekAbstract:Abstract The paper presents the results of Laser Surface Modification of the borided layers produced on the 41Cr4 medium carbon steel (0.43% C, 1.02% Cr). Laser tracks were arranged by CO2 Laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of three following zones: re-melted zone (MZ) (eutectic mixture of borides and martensite), heat-affected zone (HAZ) (martensite) and the substrate (ferrite and pearlite). XRD scans of the Laser-modified borided specimen confirmed the presence of the same two types of iron borides (FeB and Fe2B), like these indicated in the as-borided layer. After re-solidification in some places iron richer Fe3B phase was additionally formed. The layer after boriding and Laser heat treatment (LHT) has a lower microhardness, than the only borided layer, reducing the hardness gradient between the diffusion layer and the substrate. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided layers after conventional heat treatment.
-
characterization of single tracks after Laser Surface Modification of borided 41cr4 steel
Applied Surface Science, 2003Co-Authors: A. Pertek, M KulkaAbstract:Abstract The paper presents the results of Laser Surface Modification of the borided layers produced on the 41Cr4 medium carbon steel (0.43%C, 1.02%Cr). The Laser heat treatment (LHT) has been carried out by CO2 Laser beam. The microstructure and microhardness have been studied after Laser hardening of borided layers. In the microstructure after Laser Surface Modification three zones have been observed: melted zone (eutectic mixture of borides and martensite), heat affected zone (martensite) and the substrate (ferrite and pearlite). The influence of Laser heat treatment parameters (scanning rate and power) on the size and microhardness of borided layers has been determined. The layer after boriding and LHT has a lower microhardness than the only borided layer, reducing the hardness gradient between the diffusion layer and the substrate. Probably, the brittleness of this layer is lower.
F.t. Cheng - One of the best experts on this subject based on the ideXlab platform.
-
Improvement Of Cavitation Erosion Resistance and Corrosion Resistance Of Brass by Laser Surface Modification
MRS Proceedings, 2020Co-Authors: F.t. ChengAbstract:Laser Surface Modification of brass (Cu-38Zn-1.5Pb) using AISiFe and NiCrSiB alloy was achieved by using a 2kW continuous wave Nd-YAG Laser with the aim of improving the cavitation erosion resistance and corrosion resistance. The alloying powder was preplaced on the brass substrate by thermal spraying to a thickness of 350µm, followed by Laser beam scanning to effect melting, mixing and alloying. A modified Surface was achieved by overlapping of adjacent tracks. The cavitation erosion resistance and the anodic polarization characteristics of the Laser Surface modified specimens in 3.5% NaCI solution at 23°C were studied by means of a 20kHz ultrasonic vibrator at a peak to peak amplitude of 60µm and a potentiostat respectively. The cavitation erosion resistance of the specimens modified with AlSiFe and NiCrSiB was improved by a factor of 3 and 7 respectively, compared with that of the brass substrate. Potentiodynamic test, however, indicated that the corrosion resistance of specimens modified with AlSiFe deteriorated, as reflected by a shift of the polarization curve towards higher current densities. On the other hand, the corrosion resistance of specimens modified with NiCrSiB was significantly improved, as evidenced by the presence of a passive region (from −175 mV to −112 mV) and a reduction in the anodic current density by at least an order of magnitude compared with the substrate at the same anodic potential. The hardness profile and the compositional profile were measured using a Vickers hardness tester and EDX respectively. The microstructure and the Surface morphology of the specimens were investigated with the aid of SEM and optical microscopy.
-
Laser Surface Modification of Various Tool Steels for Improving Hardness and Corrosion Resistance
Key Engineering Materials, 2008Co-Authors: C.t. Kwok, F.t. Cheng, K.i. LeongAbstract:Laser Surface Modification of nine tool steels, namely, plastics mold steels (PMSs), high-speed steels (HSSs) and cold/hot-work steels (CHWSs), was achieved by means of a CW Nd:YAG Laser. The microstructure and the phases present in the Surface of the specimens were analyzed by optical microscopy, scanning-electron microscopy and X-ray diffractometry. The Surface hardness of the specimens was measured using a Vickers microhardness tester. The corrosion characteristics of the Laser Surface-melted steels in 3.5 wt% NaCl solution at 25 oC were studied by potentiodynamic polarization technique. The microstructures of the Surface of the steels were changed completely after Laser Surface melting. Some steels showed improved corrosion resistance compared with the conventionally hardened specimens due to dissolution of the alloying elements in solid solution. The hardness and corrosion characteristics of all the Laser Surface-melted specimens are strongly dependent on the amount of passivating elements in solid solution and also on the morphology of the re-precipitated carbides. Both these factors depend on the Laser processing parameters and the substrate compositions.
-
Laser Surface Modification of uns s31603 stainless steel using nicrsib alloy for enhancing cavitation erosion resistance
Surface & Coatings Technology, 1998Co-Authors: C.t. Kwok, F.t. ChengAbstract:Abstract Laser Surface Modification using NiCrSiB alloy (Ni −16.5Cr −15.5Fe −3.5Si −3.8B −0.1C) on austenitic stainless steel UNS S31603 (Fe −17.6Cr −11.2Ni −2.5Mo −1.4Mn −1.4Cu −0.4Si −0.03C) was achieved by using a 2 kW continuous wave Nd-YAG Laser. The cavitation erosion and pitting corrosion characteristics of the Laser Surface modified UNS S31603 in 3.5% NaCl solution at 23 °C were studied by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 μm and a potentiostat, respectively. The NiCrSiB alloy layer was flame sprayed on the Surface of UNS S31603 stainless steel. The Surface was then scanned with the Laser beam. The melt depth and dilution of the sprayed layer with the substrate material increased with the decrease of scanning speed. At low dilution ratio of sprayed layer thickness to melt depth, less secondary phases such as CrB, CrB 2 , Fe 2 B and M 7 (CB) 3 and low hardness were observed in the Laser-modified layer. The cavitation erosion resistance R e (reciprocal of the mean depth of penetration) of the Laser-modified specimen with a dilution ratio of 0.65 was improved by 2.7 times as compared with that of the as-received UNS S31603 specimen. In addition, the pitting potential was close to that of the as-received UNS S31603 and the protection potential shifted in the noble direction by a substantial amount (from −3 to 121 mV). The R e of the Laser Surface modified specimen with dilution ratio of 0.88 was improved by four times as compared with that of the as-received UNS S31603 and very close to that of super duplex stainless steel UNS S32760 (Fe −25.6Cr −7.2Ni −4Mo −0.6Mn −0.7Cu −0.8W −0.3Si −0.2N −0.03C). However, its pitting potential was lowered from 359 to 50 mV and its protection potential shifted in the active direction from −3 to −238 mV. On the other hand, the degree of pitting damage as judged from the pitting morphology was less severe in the Laser Surface modified specimens. The R e of Laser Surface modified UNS S31603 was found to be linearly related to hardness. The deformation mechanism by cavitation erosion of the Laser-modified specimens was also investigated.
Dermot Brabazon - One of the best experts on this subject based on the ideXlab platform.
-
high speed Laser Surface Modification of ti 6al 4v
Surface & Coatings Technology, 2012Co-Authors: Evans Chikarakara, Sumsun Naher, Dermot BrabazonAbstract:Titanium and its alloys have been commonly used for biomedical implant applications for many years; however, associated high coefficient of friction, wear characteristics and low hardness have limited their long term performance. This article investigates the effects of the high speed Laser Surface Modification of Ti–6Al–4V on the microstructure, Surface roughness, meltpool depth, phase transformation, residual strain, microhardness, and chemical composition. Laser treatment was carried out using a 1.5 kW CO2 Laser in an argon gas environment. Irradiance and residence time were varied between 15.7 to 26.7 kW/mm2 and 1.08 to 2.16 ms respectively. Laser treatment resulted in a 20 to 50 μm thick Surface modified layer without cracks. An increase in residence time and irradiance resulted in higher depth of processing. Surface roughness was found to decrease with increase in both irradiance and residence time. Metallography showed that a martensite structure formed on the Laser treated region producing acicular α-Ti nested within the aged β matrix. The Laser treatment reduced volume percentage of β-Ti as compared to the non-treated Surface. Lattice stains in the range of 0.81% to 0.91% were observed after Laser Surface Modification. A significant increase in microhardness was recorded for all Laser treated samples. Microhardness increased up to 760 HV0.05 which represented a 67% increase compared to the bulk material. Energy Dispersive X-ray Spectroscopy (EDS) analysis showed that Laser Surface Modification produced a more homogenous chemical composition of the alloying elements compared to the untreated bulk metal.
-
Laser Surface Modification of H13 die steel using different Laser spot sizes
2011Co-Authors: S.n. Aqida, Sumsun Naher, Dermot BrabazonAbstract:This paper presents a Laser Surface Modification process of AISI H13 tool steel using three sizes of Laser spot with an aim to achieve reduced grain size and Surface roughness. A Rofin DC‐015 diffusion‐cooled CO2 slab Laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were Laser peak power, overlap percentage and pulse repetition frequency (PRF). Metallographic study and image analysis were done to measure the grain size and the modified Surface roughness was measured using two‐dimensional Surface profilometer. From metallographic study, the smallest grain sizes measured by Laser modified Surface were between 0.51 μm and 2.54 μm. The minimum Surface roughness, Ra, recorded was 3.0 μm. This Surface roughness of the modified die steel is similar to the Surface quality of cast products. The grain size correlation with hardness followed the findings corre...
-
Designing pulse Laser Surface Modification of H13 steel using response Surface method
2011Co-Authors: S.n. Aqida, Dermot Brabazon, Sumsun NaherAbstract:This paper presents a design of experiment (DOE) for Laser Surface Modification process of AISI H13 tool steel in achieving the maximum hardness and minimum Surface roughness at a range of modified layer depth. A Rofin DC‐015 diffusion‐cooled CO2 slab Laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were Laser peak power, overlap percentage and pulse repetition frequency (PRF). The response Surface method with Box‐Behnken design approach in Design Expert 7 software was used to design the H13 Laser Surface Modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified Surface roughness was measured using two‐dimensional Surface profilometer. The correlation of the three Laser processing parameters and the modified Surface properties was specified by plotting three‐dimensional graph. The hardn...
-
Laser Surface Modification of Ti-6Al-4V for biomedical applications
2010Co-Authors: Evans Chikarakara, Sumsun Naher, Dermot BrabazonAbstract:Introduction. Ti-6Al-4V is used in biomedical engineering due to its excellent properties: high strength to weight ratio, low density, high corrosion resistance and good biocompatibility. However, the use of the alloy under severe friction conditions is restricted due to poor tribological properties such as high coefficient of friction and low hardness [1, 2]. Laser Surface Modification is known for its improved mechanical and tribological properties for biomedical titanium alloys. The treatment produces minimal contamination and increases osseointegration [3-5]. The present study evaluated the effects of high speed, Laser processing parameters on Surface roughness, hardness, chemical composition and biocompatibility. Materials and Methods A 1.5KW CO2 Laser in continuous mode was irradiated on flat Ti-6Al-4V samples at three levels of irradiance 15.72, 20.43 and 26.72 KW/cm2 and three levels of residence time 1.08, 1.44 and 2.16 ms. Evaluation of the Surface was carried out by scanning electron microscope (SEM) examination and mechanical profilometry in accordance to ISO 4287/4288. SEM analysis of the Surface topography resulting from the various Laser treatments was carried out. Energy Dispersive Spectroscopy (EDS) analysis was used to determine the chemical composition of the treated areas. The effect of Surface topography on cellular attachment was investigated in vitro using MC3T3-E1 pre-osteoblast cells. Cell attachment was determined using the Hoechst DNA assay and cell morphology was examined using SEM analysis. Results and Discussion An increase in residence time resulted in improved depth of processing. An increase in irradiance did not always produce an increase in depth of processing; however higher irradiance levels were found to provide for a more uniform depth of processing which reached a maximum of 80 µm. Irradiation with the scanning beam produced a single phase microstructure, see Figure 1. This single phase occurred when various constituents in the alloy have dissolved with rapid solidification thwarting segregation of the various alloying elements into high and low concentration [6]. Improved homogenous chemical composition of the Laser modified region was verified by the EDS analysis. Microhardness examination revealed an increase in hardness of up to 67% after Laser treatment. A relationship between irradiance and roughness was observed, roughness decreasing with increase in irradiance.
Narendra B. Dahotre - One of the best experts on this subject based on the ideXlab platform.
-
Laser Surface Modification of AZ31BMg alloy for bio-wettability
2020Co-Authors: Yee-hsien Ho, Hitesh D. Vora, Narendra B. DahotreAbstract:AbstractMagnesium alloys are the potential degradable materials for load-bearing implant application due to their comparablemechanical properties to human bone, excellent bioactivity, and in vivo non-toxicity. However, for a successful load-bearing implant, the Surface of bio-implant must allow protein absorption and layer formation under physiologicalenvironment that can assist the cell/osteoblast growth. In this regard, Surface wettability of bio-implant plays a keyrole to dictate the quantity of protein absorption. In light of this, the main objective of the present study was to producefavorable bio-wettability condition of AZ31B Mg alloy bio-implant Surface via Laser Surface Modification technique undervarious Laser processing conditions. In the present efforts, the influence of Laser Surface Modification on AZ31B Mg alloySurface on resultant bio-wettability was investigated via contact-angle measurements and the co-relationships amongmicrostructure (grain size), Surface roughness, Surface energy, and Surface chemical composition were established. Inaddition, the Laser Surface Modification technique was simulated by computational (thermal) model to facilitate theprediction of temperature and its resultant cooling/solidification rates under various Laser processing conditions forcorrelating with their corresponding composition and phase evolution. These predicted thermal properties were laterused to correlate with the corresponding microstructure, chemical composition, and phase evolution via experimentalanalyses (X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy).KeywordsLaser Surface Modification, bio-implant, bio-wettability, grain refinement, contact-angle measurement, Surface energy
-
Computational prediction of grain size during rapid Laser Surface Modification of Al–O ceramic
Physica Status Solidi-rapid Research Letters, 2020Co-Authors: Anoop N. Samant, Narendra B. DahotreAbstract:The aim of this letter is to present a model including the fundamental non-equilibrium effects to predict the microstructure evolution during the rapid solidification of Laser Surface modified Al–O ceramic system to understand grain growth and the physical process involved during the treatment. The obtained data is then compared with the actual measurements from micrographs. This approach is novel compared to other work in the similar field which have looked at the process only at the macroscopic level that included the extractions of macroscopic features such as melt depth and width. Such study is important as Laser Surface Modification can be extended to dressing of alumina grinding wheel material, a part of the Al–O ceramic system. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
-
Laser Surface Modification of az31b mg alloy for bio wettability
Journal of Biomaterials Applications, 2015Co-Authors: Yee-hsien Ho, Hitesh D. Vora, Narendra B. DahotreAbstract:Laser Surface Modification of AZ31B Magnesium alloy changes Surface composition and roughness to provide improved Surface bio-wettability. Laser processing resulted in phase transformation and grain refinement due to rapid quenching effect. Furthermore, instantaneous heating and vaporization resulted in removal of material, leading the textured Surface generation. A study was conducted on a continuum-wave diode-pumped ytterbium Laser to create multiple tracks for determining the resulting bio-wettability. Five different Laser input powers were processed on Mg alloy, and then examined by XRD, SEM, optical profilometer, and contact angle measurement. A finite element based heat transfer model was developed using COMSOL multi-physics package to predict the temperature evolution during Laser processing. The thermal histories predicted by the model are used to evaluate the cooling rates and solidification rate and the associated changes in the microstructure. The Surface energy of Laser Surface Modification samples can be calculated by measuring the contact angle with 3 different standard liquid (D.I water, Formamide, and 1-Bromonaphthalen). The bio-wettability of the Laser Surface Modification samples can be conducted by simulated body fluid contact angle measurement. The results of SEM, 3D morphology, XRD, and contact angle measurement show that the grain size and roughness play role for wetting behavior of Laser processing Mg samples. Surface with low roughness and large grain size performs as hydrophilicity. On the contrast, Surface with high roughness and small grain size performs as hydrophobicity.
-
The Laser Surface Modification of advanced ceramics: A modeling approach
JOM, 2007Co-Authors: Anoop N. Samant, Sandip P. Harimkar, Narendra B. DahotreAbstract:A numerical approach for predicting microstructures during the Laser Surface Modification of ceramics has been proposed. Laser Surface Modification is a near-non-equilibrium or non-equilibrium process involving high cooling rates (10^2–10^8 K/s) leading to rapid solidification. As the basic governing solidification theory behind conventional processes like casting and Laser processing is the same, the approach and the theory behind the conventional processes can be extended to such near-non-equilibrium processes by adequately modifying the conventional models. This study looks at various challenges in modeling the Laser processing phenomena and elaborates on present efforts and future modeling goals.
-
Laser Surface Modification of zinc-base composites
JOM, 1990Co-Authors: Narendra B. Dahotre, T. Dwayne Mccay, Mary Helen MccayAbstract:The unique, ultrafine microstructure that evolves during Laser Surface Modification of a zinc-base metal-matrix composite (MMC) directly affects Surface properties such as corrosion and wear. Preliminary studies indicate that over the experimental range of conditions, the corrosion rate and the wear rate of the Laser Surface-treated MMC are lower than of that the untreated MMC. Further, x-ray diffractometry analysis of the Laser Surface-treated sample shows that unconventional, nonequilibrium phases are created in the process.
