Lubomir Caplovic | Slovak University of Technology (original) (raw)

Papers by Lubomir Caplovic

Processing and Application of Ceramics

Ceramic composites consisting of a boron carbide (B4C) matrix and titanium diboride (TiB2) second... more Ceramic composites consisting of a boron carbide (B4C) matrix and titanium diboride (TiB2) secondary phase were obtained by reactive sintering from boron carbide powder with 40 and 50wt.% of titanium dioxide (TiO2) additive. The same sintering temperature of 1850?C and pressure of 35MPa, but different sintering times from 15 to 60min, were applied during reactive hot pressing of the composites in vacuum. The effects of TiO2 content and sintering time on phase compositions, microstructures and mechanical properties of the composites were studied. The TiO2 additive enhanced densification of the B4C-TiB2 ceramic composites. Both Vickers hardness and the fracture toughness of the composites increased with prolongation of sintering time. The highest hardness of 29.8GPa was achieved for the composite with 29.6 vol.% of TiB2 obtained by sintering of the precursor with 40wt.% of TiO2 additive for 60min. The fracture toughness reached a maximum value of 7.5MPa?m1/2 for the composite containi...

The Paton Welding Journal, 2021

Strojniški vestnik – Journal of Mechanical Engineering, 2012

Journal of Materials Engineering and Performance, Oct 4, 2018

Explosive welding of titanium Grade 1 to AW7075 aluminum alloy arranged in parallel setup was per... more Explosive welding of titanium Grade 1 to AW7075 aluminum alloy arranged in parallel setup was performed. The annealing of produced bimetals at the temperatures of 450, 500 and 550°C for times ranging from 20 to 100 h was carried out after explosive welding. The produced bimetal was characteristic by its wavy interface typical for that bonding process. Increase in the microhardness at the interface was recorded due to work hardening. Delamination of titanium Grade 1 flyer sheet was firstly observed when annealing temperature of 500°C for 40 h was carried out. Annealing at 550°C also resulted in delamination of upper sheet. The intermetallic compound (IMC) layer was observed at the interface after annealing of bimetals. The higher the annealing temperature and time, the higher the thickness of continuous IMC layer. The maximum measured thickness of IMC layer averaged 13 µm. Energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) analyses revealed that the interface layer is consisted of Al 18 Ti 2 Mg 3 IMC. Microhardness at the interface increased dramatically up to 439 HV0.1 after annealing of bimetal due to the presence of above-mentioned IMC.

Journal of Materials Science, Dec 13, 2014

In this paper, nanosuspensions of three arsenic sulfide (As 4 S 4) compounds, commercial syntheti... more In this paper, nanosuspensions of three arsenic sulfide (As 4 S 4) compounds, commercial synthetic arsenic(II) sulfide, and natural realgar and pararealgar minerals were prepared. Nanosuspensions were obtained by ultrafine wet milling in a circulation mill. The zeta potential and particle size distribution were measured for stability estimation. Structural changes were studied using Raman and Fourier transform infrared spectroscopic methods and positron annihilation lifetime method. The morphology of the prepared nanoparticles was determined using scanning and transmission electron microscopy. The anticancer effects were tested using flow cytometry and western blotting analysis. The average particle size in the individual samples varied from 137 to 153 nm. The effects of milling were associated with the formation of arsenic sulfide crystalline nanoparticles and the fragmentation of the corresponding free-volume entities. Consequently, an increase in the arsenic dissolution was observed. The anticancer effects of the nanosuspensions were verified on the human cancer H460 cell line, in which case DNA damage and greater numbers of apoptotic cells were observed.

Journal of physics, Feb 1, 2017

Key Engineering Materials, May 1, 2015

Materials, May 22, 2019

The microstructure, phase constitution, and corrosion performance of as-solidified Al 70 Pd 25 Co... more The microstructure, phase constitution, and corrosion performance of as-solidified Al 70 Pd 25 Co 5 and Al 74 Pd 12 Co 14 alloys (element concentrations in at.%) have been investigated in the present work. The alloys were prepared by arc-melting of Al, Pd, and Co lumps in argon. The Al 74 Pd 12 Co 14 alloy was composed of structurally complex ε n phase, while the Al 70 Pd 25 Co 5 alloy was composed of ε n and δ phases. The corrosion performance was studied by open circuit potential measurements and potentiodynamic polarization in aqueous NaCl solution (3.5 wt.%). Marked open circuit potential oscillations of the Al 70 Pd 25 Co 5 alloy have been observed, indicating individual breakdown and re-passivation events on the sample surface. A preferential corrosion attack of ε n was found, while the binary δ phase (Al 3 Pd 2) remained free of corrosion. A de-alloying of Al from ε n and formation of intermittent interpenetrating channel networks occurred in both alloys. The corrosion behavior of ε n is discussed in terms of its chemical composition and crystal structure. The corrosion activity of ε n could be further exploited in preparation of porous Pd-Co networks with possible catalytic activity.

Nanomaterials

The present work investigates the influence of isothermal annealing on the microstructure and oxi... more The present work investigates the influence of isothermal annealing on the microstructure and oxidation behavior of nanocomposite coatings. AlTiSiN/TiSiN coatings with TiSiN adhesive layer were deposited onto a high-speed steel substrate via physical vapor deposition. The coatings were investigated in the as-deposited state as well as after annealing in air at 700, 800, 900 and 1000 °C, respectively. The microstructure and morphology of the coatings were observed using scanning electron microscopy and transmission electron microscopy. The chemical composition and presence of oxidation products were studied by energy-dispersive X-ray spectroscopy. The phase identification was performed by means of X-ray diffraction. In the microstructure of the as-deposited coating, the (Ti1-xAlx)N particles were embedded in an amorphous Si3N4 matrix. TiO2 and SiO2 were found at all annealing temperatures, and Al2O3 was additionally identified at 1000 °C. It was found that, with increasing annealing ...

The ledeburitic steel Vanadis 6 has been austenitized at the temperatures 1000 – 1075 o C, nitrog... more The ledeburitic steel Vanadis 6 has been austenitized at the temperatures 1000 – 1075 o C, nitrogen gas quenched and 2x tempered at the temperatures 480 – 600 o C. Each tempering cycle was 2 h. Sub-zero treatment carried out via various regimes has been inserted in-between quenching and tempering, except one set of specimens. The effect of sub-zero treatment on the tempering characteristics of the material has been investigated. It has been found that the martensite after sub-zero processing differs from that of conventionally transformed in terms of substructure. The sub-zero treatment induced a multiple reduction of the volume fraction of retained austenite. This makes a difference between as-tempered microstructure of sub-zero treated and no-sub-zero treated steel, which results in different as-tempered hardness.

IOP Conference Series: Materials Science and Engineering, 2020

In the present work, Ti-Al-C-N coatings were deposited on cemented carbide substrates by lateral ... more In the present work, Ti-Al-C-N coatings were deposited on cemented carbide substrates by lateral rotating cathodes (LARC®) process using Platit π80+DLC deposition unit. The effect of C2H2 gas flow rate on elemental and phase composition, deposition rate, cross-sectional and surface morphology, mechanical and tribological properties of the coatings was studied. Following analytical techniques, namely: scanning electron microscopy (SEM) with energy and wave dispersive X-ray spectroscopy (EDS and WDS), X-ray diffraction analysis (XRD), nanoindentation measurements, Rockwell C indentation test and tribological testing were used for Ti-Al-C-N coatings evaluation. From the EDS analysis, it was found that the carbon content in the coatings increased from 0 at.% to 22.3 at.% as the C2H2 gas flow rate increased from 0 sccm to 75 sccm. The increase in deposition rate of coatings from 0.029 μm/min to 0.052 μm/min was documented. From XRD results it was found that the coatings consist of a cubi...

IOP Conference Series: Materials Science and Engineering, 2020

The main of this work is to investigate the impact of the isothermal annealing on the structure a... more The main of this work is to investigate the impact of the isothermal annealing on the structure and morphological changes on the PVD hard coatings. Three different coatings based on the AlTiN system were deposited onto cemented carbide substrates containing 6 wt% of Co. Two coatings AlTiN/TiAlN and AlTiN/TiN with an initial thickness of 3 μm has a coarse-grained columnar structure with a chemically graded nanomultilayering consisting of alternating Ti-rich and Al-rich layers. In the case of the AlTiN/TiAlN coating, a total of 20 layers were applied. Ten layers had a thickness of 200 nm (AlTiN) and 10 layers with the thickness of 100 nm (TiAlN). The same number of nanolayers was also retained for the AlTiN/TiN multilayer coating. The TiN layers were 100 nm thick. The third coating was a nanocomposite sandwich coating formed by a TiSiN adhesive layer (50nm), a functional nanocomposite AlTiSiN layer (2 μm) and a top functional TiSiN layer with a thickness of 1 μm. The coatings were pre...

Acta Metallurgica Slovaca, 2020

Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by... more Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by in situ reactive sintering of the initial powder mixture B4C-Al with concentration from 5 to 25 wt.% Al sintering additives. The composite samples were hot pressed at the temperature of 1850 °C, pressure of 35 MPa, for 15 min in a vacuum atmosphere. The portion of Al8B4C7 secondary phase increased from 3.3 to 22.1 wt.% when increasing the concentration of Al sintering additive from 5 to 25 wt.% Al. Significant improving of densification and mechanical properties was measured at increasing of Al sintering additive concentration from 5 to 10 wt.% Al. The highest average hardness of 28.74 GPa was achieved when adding 15 wt.% Al sintering additive. The fracture toughness increased with concentration of Al sintering additive in whole concentration range with the highest average value of 5.92 MPa.m1/2 at 25 wt.% Al sintering additives.

Journal of Materials Engineering and Performance, 2019

Explosive welding of AW5754 aluminum alloy to AZ31B magnesium alloy was performed. AW5754 was pro... more Explosive welding of AW5754 aluminum alloy to AZ31B magnesium alloy was performed. AW5754 was proposed as a flyer plate. A parallel setup was used during explosive welding. The annealing of AW5754/ AZ31B composite plate at 250, 300 and 350°C for 2, 3, 4 and 5 h was performed after explosive welding. Bimetals were characterized by regular wavy interface. Annealing resulted in the creation of intermetallic compounds (IMCs). The increase in the thickness of IMC interfacial layer was observed with increasing of annealing temperature and time. IMC layer of highest thickness was recorded after annealing at 350°C for 5 h and averaged 67 lm. EDS analysis showed that the interfacial layer close to AW5754 alloy was formed by Al 3 Mg 2 IMC, and interfacial layer adjacent to the AZ31B alloy consisted of Mg 17 Al 12 IMC. Bright particles were spread at the AW5754-Al 3 Mg 2 IMC interface. Rise in the microhardness at the interface of produced bimetal was associated with work hardening. Microhardness values increased to 218 HV0.025 after annealing process due to IMCs present at the interface. Decrease in microhardness in locations close to the IMC interfacial layer was found after heat treatment due to recrystallization. The bimetal tensile strength reached 120 MPa. The annealing resulted in decrease in the bimetal tensile strength.

Vacuum, 2019

The microstructure of Vanadis 6 ledeburitic steel subjected to sub-zero treatments at À 140 � C f... more The microstructure of Vanadis 6 ledeburitic steel subjected to sub-zero treatments at À 140 � C for different durations followed by various tempering regimes was investigated. The obtained results infer that: i) retained austenite amount is fivefold reduced by this treatment, and compressive stresses higher than 1500 MPa are generated in this phase, ii) martensite is refined due to SZT, and it contains enhanced number of crystal defects, iii) great number of "extra" cementitic carbides is formed during the sub-zero period; this number is higher than what is achieved by sub-zero treatments at À 196 � C, iv) the number of "extra" carbides decreases with tempering, however, it remains higher than after in both the conventionally quenched and sub-zero treated at À 196 � C steel, v) sub-zero treatments at À 140 � C modify the precipitation behaviour substantially; coherent nano-sized ε-carbides and cementite were found already prior tempering the steel, and besides the cementite also M 7 C 3 phase was detected after tempering treatment.

Research Papers Faculty of Materials Science and Technology Slovak University of Technology, 2013

Titanium alloys are utilized especially in applications that require a good combination of high s... more Titanium alloys are utilized especially in applications that require a good combination of high strength, low mass and good corrosion resistance in aggressive environments. However, mechanical properties prejudge titanium alloys to hard machinability. Machining of titanium alloys is usually accompanied by cooling with liquids or gasses. One of the most effective cooling approaches is cooling by liquid nitrogen. Liquid nitrogen decreases temperature of tool, but also increases strength, hardness and brittleness of workpiece. One of the most suitable machining methods to machine hard and brittle materials is ultrasonic machining. In this article, rotary ultrasonic machining of titanium alloys under cryogenic conditions is analyzed.

Applied Surface Science, 2018

TiO 2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of t... more TiO 2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H 2 /Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and Xray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 m, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT

Vacuum, 2017

The aim of this paper is to investigate effect of cathode current on the properties of a series o... more The aim of this paper is to investigate effect of cathode current on the properties of a series of CrAlSiN nanocomposite monocoatings prepared by the lateral rotating cathodes arc technique using the PLATIT p 80 þ DLC coating device and were deposited onto high speed steel HSS 6-5-2-5. The influence of the cathode arc current as well as increasing in the Al and Si content were studied in order to determine the coating properties. A sudden change of preferred orientation from (111) / (002) was observed in the interval from 1.3 to 1.7 at. % of Si, and 13.0 to 15.0 at. % Al, respectively. This change of preferred orientation is due to the incorporation of Al and Si into coatings, which also leads to an increased volume of Si 3 N 4 matrix. All as-deposited coatings exhibit continuous nanohardness increment from 30 ± 1.8 to 34.2 ± 1.5 GPa with increasing Al þ Si due to strengthening the solid solution and precipitation of the Si 3 N 4 silicon nitride from the saturated CrAlSiN lattice at~2.3 at. % of Si. Coatings deposited with cathode current ratio (CCR) ! 1.00 satisfy the H/E* ! 0.1 condition for simultaneously hard and tough coatings. The chemical composition, XRD structure, residual stresses, surface roughness and nanohardness were systematically characterised using a scanning electron microscope (SEM) fitted with Energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), laser scanning confocal microscope (LSCM) and nanoindentation.

Journal of Alloys and Compounds, 2017

Rapid synthesis of delafossite CuAlO 2 using a mechanically activated mixture of microcrystalline... more Rapid synthesis of delafossite CuAlO 2 using a mechanically activated mixture of microcrystalline Cu 2 O and nanocrystalline Al 2 O 3 powder was achieved after subsequent annealing under argon atmosphere. The results were analyzed by using X-ray diffractometry, thermal analysis, transmission and scanning electron microscopy, Raman and X-ray photoelectron spectroscopy and SQUID magnetometry. The presence of core-shell configuration of Cu 2 O nanoparticles with the thickness of the non-crystalline surface shell of

Microporous and Mesoporous Materials, 2017

Biomimetic sol-gel synthesis was used to prepare new FeO(OH) zeolite (clinoptilolite tuff) adsorb... more Biomimetic sol-gel synthesis was used to prepare new FeO(OH) zeolite (clinoptilolite tuff) adsorbent effective for antimony removal. The product was compared with other on the market accessible natural or commercial adsorption materials like granulated ferric hydroxide GEH, powder of zero valent iron (ZVI)nanofer and the new synthesized oxi(hydr)oxide FeO(OH) and characterized by XRD, XPS, Raman, FT IR, TG, DTA, DTG, TEM and SEM techniques. Based upon the SEM analysis, the oxidized nanofer sample revealed the existence of hematite and goethite and morphology of FeO(OH) dopant confirmed the presence of ferrihydrite, in less extent also magnetite and hematite. Recorded exothermic maxima on DTA curves for powdered FeO(OH) zeolite at 460°C and for pure component FeO(OH) at 560°C indicated an 100°C shifted exothermic effect, which characterized strong chemical interaction of FeO(OH) with zeolite structure. Based upon the XPS analyses, also the difference between Fe species in the raw and FeO(OH) doped zeolite was found in increasing Si/Al ratio, however only at the surface below app. 5 nm, measured as 3.94 for raw and 5.38 for sample treated with alkalic solution. The plotting of adsorption isotherms in the system studied clearly showed the increasing uptake capacity of the adsorbents towards antimony with the increased S(BET) data (GEH ˃FeO(OH)˃FeO(OH) zeolite˃nanofer).

Processing and Application of Ceramics

Ceramic composites consisting of a boron carbide (B4C) matrix and titanium diboride (TiB2) second... more Ceramic composites consisting of a boron carbide (B4C) matrix and titanium diboride (TiB2) secondary phase were obtained by reactive sintering from boron carbide powder with 40 and 50wt.% of titanium dioxide (TiO2) additive. The same sintering temperature of 1850?C and pressure of 35MPa, but different sintering times from 15 to 60min, were applied during reactive hot pressing of the composites in vacuum. The effects of TiO2 content and sintering time on phase compositions, microstructures and mechanical properties of the composites were studied. The TiO2 additive enhanced densification of the B4C-TiB2 ceramic composites. Both Vickers hardness and the fracture toughness of the composites increased with prolongation of sintering time. The highest hardness of 29.8GPa was achieved for the composite with 29.6 vol.% of TiB2 obtained by sintering of the precursor with 40wt.% of TiO2 additive for 60min. The fracture toughness reached a maximum value of 7.5MPa?m1/2 for the composite containi...

The Paton Welding Journal, 2021

Strojniški vestnik – Journal of Mechanical Engineering, 2012

Journal of Materials Engineering and Performance, Oct 4, 2018

Explosive welding of titanium Grade 1 to AW7075 aluminum alloy arranged in parallel setup was per... more Explosive welding of titanium Grade 1 to AW7075 aluminum alloy arranged in parallel setup was performed. The annealing of produced bimetals at the temperatures of 450, 500 and 550°C for times ranging from 20 to 100 h was carried out after explosive welding. The produced bimetal was characteristic by its wavy interface typical for that bonding process. Increase in the microhardness at the interface was recorded due to work hardening. Delamination of titanium Grade 1 flyer sheet was firstly observed when annealing temperature of 500°C for 40 h was carried out. Annealing at 550°C also resulted in delamination of upper sheet. The intermetallic compound (IMC) layer was observed at the interface after annealing of bimetals. The higher the annealing temperature and time, the higher the thickness of continuous IMC layer. The maximum measured thickness of IMC layer averaged 13 µm. Energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) analyses revealed that the interface layer is consisted of Al 18 Ti 2 Mg 3 IMC. Microhardness at the interface increased dramatically up to 439 HV0.1 after annealing of bimetal due to the presence of above-mentioned IMC.

Journal of Materials Science, Dec 13, 2014

In this paper, nanosuspensions of three arsenic sulfide (As 4 S 4) compounds, commercial syntheti... more In this paper, nanosuspensions of three arsenic sulfide (As 4 S 4) compounds, commercial synthetic arsenic(II) sulfide, and natural realgar and pararealgar minerals were prepared. Nanosuspensions were obtained by ultrafine wet milling in a circulation mill. The zeta potential and particle size distribution were measured for stability estimation. Structural changes were studied using Raman and Fourier transform infrared spectroscopic methods and positron annihilation lifetime method. The morphology of the prepared nanoparticles was determined using scanning and transmission electron microscopy. The anticancer effects were tested using flow cytometry and western blotting analysis. The average particle size in the individual samples varied from 137 to 153 nm. The effects of milling were associated with the formation of arsenic sulfide crystalline nanoparticles and the fragmentation of the corresponding free-volume entities. Consequently, an increase in the arsenic dissolution was observed. The anticancer effects of the nanosuspensions were verified on the human cancer H460 cell line, in which case DNA damage and greater numbers of apoptotic cells were observed.

Journal of physics, Feb 1, 2017

Key Engineering Materials, May 1, 2015

Materials, May 22, 2019

The microstructure, phase constitution, and corrosion performance of as-solidified Al 70 Pd 25 Co... more The microstructure, phase constitution, and corrosion performance of as-solidified Al 70 Pd 25 Co 5 and Al 74 Pd 12 Co 14 alloys (element concentrations in at.%) have been investigated in the present work. The alloys were prepared by arc-melting of Al, Pd, and Co lumps in argon. The Al 74 Pd 12 Co 14 alloy was composed of structurally complex ε n phase, while the Al 70 Pd 25 Co 5 alloy was composed of ε n and δ phases. The corrosion performance was studied by open circuit potential measurements and potentiodynamic polarization in aqueous NaCl solution (3.5 wt.%). Marked open circuit potential oscillations of the Al 70 Pd 25 Co 5 alloy have been observed, indicating individual breakdown and re-passivation events on the sample surface. A preferential corrosion attack of ε n was found, while the binary δ phase (Al 3 Pd 2) remained free of corrosion. A de-alloying of Al from ε n and formation of intermittent interpenetrating channel networks occurred in both alloys. The corrosion behavior of ε n is discussed in terms of its chemical composition and crystal structure. The corrosion activity of ε n could be further exploited in preparation of porous Pd-Co networks with possible catalytic activity.

Nanomaterials

The present work investigates the influence of isothermal annealing on the microstructure and oxi... more The present work investigates the influence of isothermal annealing on the microstructure and oxidation behavior of nanocomposite coatings. AlTiSiN/TiSiN coatings with TiSiN adhesive layer were deposited onto a high-speed steel substrate via physical vapor deposition. The coatings were investigated in the as-deposited state as well as after annealing in air at 700, 800, 900 and 1000 °C, respectively. The microstructure and morphology of the coatings were observed using scanning electron microscopy and transmission electron microscopy. The chemical composition and presence of oxidation products were studied by energy-dispersive X-ray spectroscopy. The phase identification was performed by means of X-ray diffraction. In the microstructure of the as-deposited coating, the (Ti1-xAlx)N particles were embedded in an amorphous Si3N4 matrix. TiO2 and SiO2 were found at all annealing temperatures, and Al2O3 was additionally identified at 1000 °C. It was found that, with increasing annealing ...

The ledeburitic steel Vanadis 6 has been austenitized at the temperatures 1000 – 1075 o C, nitrog... more The ledeburitic steel Vanadis 6 has been austenitized at the temperatures 1000 – 1075 o C, nitrogen gas quenched and 2x tempered at the temperatures 480 – 600 o C. Each tempering cycle was 2 h. Sub-zero treatment carried out via various regimes has been inserted in-between quenching and tempering, except one set of specimens. The effect of sub-zero treatment on the tempering characteristics of the material has been investigated. It has been found that the martensite after sub-zero processing differs from that of conventionally transformed in terms of substructure. The sub-zero treatment induced a multiple reduction of the volume fraction of retained austenite. This makes a difference between as-tempered microstructure of sub-zero treated and no-sub-zero treated steel, which results in different as-tempered hardness.

IOP Conference Series: Materials Science and Engineering, 2020

In the present work, Ti-Al-C-N coatings were deposited on cemented carbide substrates by lateral ... more In the present work, Ti-Al-C-N coatings were deposited on cemented carbide substrates by lateral rotating cathodes (LARC®) process using Platit π80+DLC deposition unit. The effect of C2H2 gas flow rate on elemental and phase composition, deposition rate, cross-sectional and surface morphology, mechanical and tribological properties of the coatings was studied. Following analytical techniques, namely: scanning electron microscopy (SEM) with energy and wave dispersive X-ray spectroscopy (EDS and WDS), X-ray diffraction analysis (XRD), nanoindentation measurements, Rockwell C indentation test and tribological testing were used for Ti-Al-C-N coatings evaluation. From the EDS analysis, it was found that the carbon content in the coatings increased from 0 at.% to 22.3 at.% as the C2H2 gas flow rate increased from 0 sccm to 75 sccm. The increase in deposition rate of coatings from 0.029 μm/min to 0.052 μm/min was documented. From XRD results it was found that the coatings consist of a cubi...

IOP Conference Series: Materials Science and Engineering, 2020

The main of this work is to investigate the impact of the isothermal annealing on the structure a... more The main of this work is to investigate the impact of the isothermal annealing on the structure and morphological changes on the PVD hard coatings. Three different coatings based on the AlTiN system were deposited onto cemented carbide substrates containing 6 wt% of Co. Two coatings AlTiN/TiAlN and AlTiN/TiN with an initial thickness of 3 μm has a coarse-grained columnar structure with a chemically graded nanomultilayering consisting of alternating Ti-rich and Al-rich layers. In the case of the AlTiN/TiAlN coating, a total of 20 layers were applied. Ten layers had a thickness of 200 nm (AlTiN) and 10 layers with the thickness of 100 nm (TiAlN). The same number of nanolayers was also retained for the AlTiN/TiN multilayer coating. The TiN layers were 100 nm thick. The third coating was a nanocomposite sandwich coating formed by a TiSiN adhesive layer (50nm), a functional nanocomposite AlTiSiN layer (2 μm) and a top functional TiSiN layer with a thickness of 1 μm. The coatings were pre...

Acta Metallurgica Slovaca, 2020

Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by... more Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by in situ reactive sintering of the initial powder mixture B4C-Al with concentration from 5 to 25 wt.% Al sintering additives. The composite samples were hot pressed at the temperature of 1850 °C, pressure of 35 MPa, for 15 min in a vacuum atmosphere. The portion of Al8B4C7 secondary phase increased from 3.3 to 22.1 wt.% when increasing the concentration of Al sintering additive from 5 to 25 wt.% Al. Significant improving of densification and mechanical properties was measured at increasing of Al sintering additive concentration from 5 to 10 wt.% Al. The highest average hardness of 28.74 GPa was achieved when adding 15 wt.% Al sintering additive. The fracture toughness increased with concentration of Al sintering additive in whole concentration range with the highest average value of 5.92 MPa.m1/2 at 25 wt.% Al sintering additives.

Journal of Materials Engineering and Performance, 2019

Explosive welding of AW5754 aluminum alloy to AZ31B magnesium alloy was performed. AW5754 was pro... more Explosive welding of AW5754 aluminum alloy to AZ31B magnesium alloy was performed. AW5754 was proposed as a flyer plate. A parallel setup was used during explosive welding. The annealing of AW5754/ AZ31B composite plate at 250, 300 and 350°C for 2, 3, 4 and 5 h was performed after explosive welding. Bimetals were characterized by regular wavy interface. Annealing resulted in the creation of intermetallic compounds (IMCs). The increase in the thickness of IMC interfacial layer was observed with increasing of annealing temperature and time. IMC layer of highest thickness was recorded after annealing at 350°C for 5 h and averaged 67 lm. EDS analysis showed that the interfacial layer close to AW5754 alloy was formed by Al 3 Mg 2 IMC, and interfacial layer adjacent to the AZ31B alloy consisted of Mg 17 Al 12 IMC. Bright particles were spread at the AW5754-Al 3 Mg 2 IMC interface. Rise in the microhardness at the interface of produced bimetal was associated with work hardening. Microhardness values increased to 218 HV0.025 after annealing process due to IMCs present at the interface. Decrease in microhardness in locations close to the IMC interfacial layer was found after heat treatment due to recrystallization. The bimetal tensile strength reached 120 MPa. The annealing resulted in decrease in the bimetal tensile strength.

Vacuum, 2019

The microstructure of Vanadis 6 ledeburitic steel subjected to sub-zero treatments at À 140 � C f... more The microstructure of Vanadis 6 ledeburitic steel subjected to sub-zero treatments at À 140 � C for different durations followed by various tempering regimes was investigated. The obtained results infer that: i) retained austenite amount is fivefold reduced by this treatment, and compressive stresses higher than 1500 MPa are generated in this phase, ii) martensite is refined due to SZT, and it contains enhanced number of crystal defects, iii) great number of "extra" cementitic carbides is formed during the sub-zero period; this number is higher than what is achieved by sub-zero treatments at À 196 � C, iv) the number of "extra" carbides decreases with tempering, however, it remains higher than after in both the conventionally quenched and sub-zero treated at À 196 � C steel, v) sub-zero treatments at À 140 � C modify the precipitation behaviour substantially; coherent nano-sized ε-carbides and cementite were found already prior tempering the steel, and besides the cementite also M 7 C 3 phase was detected after tempering treatment.

Research Papers Faculty of Materials Science and Technology Slovak University of Technology, 2013

Titanium alloys are utilized especially in applications that require a good combination of high s... more Titanium alloys are utilized especially in applications that require a good combination of high strength, low mass and good corrosion resistance in aggressive environments. However, mechanical properties prejudge titanium alloys to hard machinability. Machining of titanium alloys is usually accompanied by cooling with liquids or gasses. One of the most effective cooling approaches is cooling by liquid nitrogen. Liquid nitrogen decreases temperature of tool, but also increases strength, hardness and brittleness of workpiece. One of the most suitable machining methods to machine hard and brittle materials is ultrasonic machining. In this article, rotary ultrasonic machining of titanium alloys under cryogenic conditions is analyzed.

Applied Surface Science, 2018

TiO 2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of t... more TiO 2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H 2 /Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and Xray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 m, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT

Vacuum, 2017

The aim of this paper is to investigate effect of cathode current on the properties of a series o... more The aim of this paper is to investigate effect of cathode current on the properties of a series of CrAlSiN nanocomposite monocoatings prepared by the lateral rotating cathodes arc technique using the PLATIT p 80 þ DLC coating device and were deposited onto high speed steel HSS 6-5-2-5. The influence of the cathode arc current as well as increasing in the Al and Si content were studied in order to determine the coating properties. A sudden change of preferred orientation from (111) / (002) was observed in the interval from 1.3 to 1.7 at. % of Si, and 13.0 to 15.0 at. % Al, respectively. This change of preferred orientation is due to the incorporation of Al and Si into coatings, which also leads to an increased volume of Si 3 N 4 matrix. All as-deposited coatings exhibit continuous nanohardness increment from 30 ± 1.8 to 34.2 ± 1.5 GPa with increasing Al þ Si due to strengthening the solid solution and precipitation of the Si 3 N 4 silicon nitride from the saturated CrAlSiN lattice at~2.3 at. % of Si. Coatings deposited with cathode current ratio (CCR) ! 1.00 satisfy the H/E* ! 0.1 condition for simultaneously hard and tough coatings. The chemical composition, XRD structure, residual stresses, surface roughness and nanohardness were systematically characterised using a scanning electron microscope (SEM) fitted with Energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), laser scanning confocal microscope (LSCM) and nanoindentation.

Journal of Alloys and Compounds, 2017

Rapid synthesis of delafossite CuAlO 2 using a mechanically activated mixture of microcrystalline... more Rapid synthesis of delafossite CuAlO 2 using a mechanically activated mixture of microcrystalline Cu 2 O and nanocrystalline Al 2 O 3 powder was achieved after subsequent annealing under argon atmosphere. The results were analyzed by using X-ray diffractometry, thermal analysis, transmission and scanning electron microscopy, Raman and X-ray photoelectron spectroscopy and SQUID magnetometry. The presence of core-shell configuration of Cu 2 O nanoparticles with the thickness of the non-crystalline surface shell of

Microporous and Mesoporous Materials, 2017

Biomimetic sol-gel synthesis was used to prepare new FeO(OH) zeolite (clinoptilolite tuff) adsorb... more Biomimetic sol-gel synthesis was used to prepare new FeO(OH) zeolite (clinoptilolite tuff) adsorbent effective for antimony removal. The product was compared with other on the market accessible natural or commercial adsorption materials like granulated ferric hydroxide GEH, powder of zero valent iron (ZVI)nanofer and the new synthesized oxi(hydr)oxide FeO(OH) and characterized by XRD, XPS, Raman, FT IR, TG, DTA, DTG, TEM and SEM techniques. Based upon the SEM analysis, the oxidized nanofer sample revealed the existence of hematite and goethite and morphology of FeO(OH) dopant confirmed the presence of ferrihydrite, in less extent also magnetite and hematite. Recorded exothermic maxima on DTA curves for powdered FeO(OH) zeolite at 460°C and for pure component FeO(OH) at 560°C indicated an 100°C shifted exothermic effect, which characterized strong chemical interaction of FeO(OH) with zeolite structure. Based upon the XPS analyses, also the difference between Fe species in the raw and FeO(OH) doped zeolite was found in increasing Si/Al ratio, however only at the surface below app. 5 nm, measured as 3.94 for raw and 5.38 for sample treated with alkalic solution. The plotting of adsorption isotherms in the system studied clearly showed the increasing uptake capacity of the adsorbents towards antimony with the increased S(BET) data (GEH ˃FeO(OH)˃FeO(OH) zeolite˃nanofer).