Pavel Doležal

Brno University of Technology

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Jaromír Wasserbauer

Brno University of Technology

Stanislava Fintová

Czech Academy of Sciences, Institute of Physics of Materials

Josef Zapletal

Brno University of Technology

Matěj Březina

Brno University of Technology

Juliána Drábiková

Brno University of Technology

Branislav Hadzima

University of Žilina

Martin Buchtík

Brno University of Technology

Libor Mrňa

Czech Academy of Sciences, Institute of Scientific Instruments

Petr Horník

Czech Academy of Sciences, Institute of Scientific Instruments

Filip Pastorek

University of Žilina

Cooperative Institutions

Brno University of Technology

Central European Institute of Technology

University of Žilina

Czech Academy of Sciences

Czech Academy of Sciences, Institute of Physics of Materials

Czech Academy of Sciences, Institute of Scientific Instruments

Masaryk University

Advanced Coatings (Belgium)

Charles University

Czech Technical University in Prague

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Characterization of Ni-P coating prepared on a wrought AZ61 magnesium alloy via electroless deposition

Materiali in tehnologije (2017)

Martin Buchtík Petr Kosár Jaromír Wasserbauer Pavel Doležal

A low-phosphorous Ni-P coating was prepared on a wrought AZ61 magnesium alloy via electroless deposition for 1 h after an adequate substrate-surface pre-treatment.The prepared coating with a thickness of 10 μm was characterized by the uniform distribution of Ni (95.4 % mass fraction) and P (4.6 % mass fraction) in the cross-section.Microcavities present in the coating resulted in quite a low corrosion resistance of the coated magnesium alloy in a 0.1 M NaCl solution.On the other hand, the coating exhibits a high degree of adhesion, as evidenced by a scratch test, and significantly improves the AZ61 magnesium-alloy microhardness.

Electroless deposition

Deposition

Characterization

10.17222/mit.2017.029

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Citations (1)

Evolution of microstructure and electrochemical corrosion characteristics of cold compacted magnesium

Koroze a ochrana materialu (2017)

Matěj Březina Pavel Doležal Michaela Krystýnová Jozef Minda Josef Zapletal

Abstract The main advantage of magnesium and its alloys is high specific strength and biocompatibility. A modern approach to magnesium-based materials preparation is powder metallurgy. This technique allows preparation of new materials with a unique structure, chemical composition, and controlled porosity. In this study, cold compaction of magnesium powder was studied. Magnesium powder of average particle size of 30 μm was compacted applying pressures of 100 MPa, 200 MPa, 300 MPa, 400 MPa and 500 MPa at laboratory temperature. Influence of compacting pressure was studied with microstructural and electrochemical corrosion characteristics analysis. The resulting microstructure was studied in terms of light and electron microscopy. Obtained electrochemical characteristics were compared with those of wrought magnesium. Compacting pressure had a significant influence on microstructure and electrochemical characteristics of prepared bulk magnesium. With the increase in compaction pressure, the porosity decreased. Compacting pressures of 300 MPa, 400 MPa and 500 MPa led to the similar microstructure of the prepared material. Polarization resistance of compacted magnesium was much lower and samples degraded faster when compared to wrought magnesium. Also, the corrosion degradation mechanism changed due to the microstructural differences between the material states.

Powder Metallurgy

10.1515/kom-2017-0015

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Citations (5)

Biodegradation Properties Of Az31 Magnesium Alloy Coated by Dicalcium Phosphate Dihydrate

Communications - Scientific letters of the University of Zilina (2014)

Filip Pastorek Miroslav Omasta Lenka Bukovinová Pavel Doležal Branislav Hadzima

Biodegradation properties of magnesium and its alloys that can be used for implants are not satisfactory and cause serious problems. These problems can be solved by biodegradable surface coatings. Evaluation of biodegradation process of Mg-3Al-1Zn alloy surfaces after grinding and grinding followed by potential controlled electrodeposition of dicalcium phosphate dihydrate (DCPD) was investigated by electrochemical impedance spectroscopy measurements in this study. The potentiostatic electrodeposition treatment process was performed in water solution of Ca(NO3)2.4H2O, NH4H2PO4 and H2O2. The corrosion process on treated and nontreated samples after various exposure times was evaluated in 0.9% NaCl solution simulating body fluid environment at 37 °C.

Simulated body fluid

10.26552/com.c.2014.3a.189-193

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Improvement of electrochemical corrosion characteristics of AZ61 magnesium alloy with unconventional fluoride conversion coatings

Surface and Coatings Technology (2018)

Stanislava Fintová Juliána Drábiková Filip Pastorek Jakub Tkácz Ivo Kuběna

Conversion coating

Magnesium fluoride

Energy-dispersive X-ray spectroscopy

10.1016/j.surfcoat.2018.10.038

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Microstructure and mechanical properties of hybrid LasTIG welds of HSLA steel

Procedia CIRP (2018)

Hana Šebestová Petr Horník Libor Mrňa Pavel Doležal

Laser welding accompanied by tungsten inert gas welding was applied for 3 mm thick high strength low alloy S460MC steel butt joining with the aim to study the effect of arc electric current on weld cooling rate and thus weld microstructure and mechanical properties. Preheating realized by the arc decreased microhardness peaks in coarse-grained heat affected zone while strength properties were not degraded. Dissimilar S460MC to DC01 mild steel welds were performed with different positions of tungsten electrode towards the laser beam trajectory to maintain uniform weld profile.

Inert gas

10.1016/j.procir.2018.08.019

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Failure Analysis of Spherical Roller Bearing

Materials science forum (2014)

Martin Juliš Ladislav Čelko Zdeněk Spotz Pavel Doležal Zina Pavloušková

The failure of a spherical-roller bearing consisting of spherical rollers, outer and inner rings made of 100CrMn6 steel was studied. After a trial test, in which several spherical rollers were completely destroyed and a long continuous radial crack appeared in the outer ring, pitting degradation was observed on all bearing parts. The bearing components were studied (separately) by means of light and electron microscopy. The chemical composition was estimated by means of glow discharge optical emission spectroscopy. X-ray diffraction was utilized for qualitative and quantitative phase analyses. As a representative of mechanical properties, the hardness was also measured.

10.4028/www.scientific.net/msf.782.247

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Citations (1)

Preparation and Characterization of Zinc Materials Prepared by Powder Metallurgy

Metals (2017)

Michaela Krystýnová Pavel Doležal Stanislava Fintová Matěj Březina Josef Zapletal

The use of zinc-based materials as biodegradable materials for medical purposes is offered as a possible alternative to corrosion-less resistant magnesium-based materials. Zinc powders with two different particle sizes (7.5 µm and 150 µm) were processed by the methods of powder metallurgy: cold pressing, cold pressing followed by sintering and hot pressing. The microstructure of prepared materials was evaluated in terms of light optical microscopy, and the mechanical properties were analyzed with Vickers microhardness testing and three-point bend testing. Fractographic analysis of broken samples was performed with scanning electron microscopy. Particle size was shown to have a significant effect on compacts mechanical properties. The deformability of 7.5 µm particle size powder was improved by increased temperature during the processing, while in the case of larger powder, no significant influence of temperature was observed. Bending properties of prepared materials were positively influenced by elevated temperature during processing and correspond to the increasing compacting pressures. Better properties were achieved for pure zinc prepared from 150 µm particle size powder compared to materials prepared from 7.5 µm particle size powder.

Powder Metallurgy

Particle (ecology)

Hot pressing

Vickers hardness test

Characterization

10.3390/met7100396

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Citations (32)

Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications

Metals (2017)

Matěj Březina Jozef Minda Pavel Doležal Michaela Krystýnová Stanislava Fintová

Magnesium with its mechanical properties and nontoxicity is predetermined as a material for biomedical applications; however, its high reactivity is a limiting factor for its usage. Powder metallurgy is one of the promising methods for the enhancement of material mechanical properties and, due to the introduced plastic deformation, can also have a positive influence on corrosion resistance. Pure magnesium samples were prepared via powder metallurgy. Compacting pressures from 100 MPa to 500 MPa were used for samples’ preparation at room temperature and elevated temperatures. The microstructure of the obtained compacts was analyzed in terms of microscopy. The three-point bendisng test and microhardness testing were adopted to define the compacts’ mechanical properties, discussing the results with respect to fractographic analysis. Electrochemical corrosion properties analyzed with electrochemical impedance spectroscopy carried out in HBSS (Hank’s Balanced Salt Solution) and enriched HBSS were correlated with the metallographic analysis of the corrosion process. Cold compacted materials were very brittle with low strength (up to 50 MPa) and microhardness (up to 50 HV (load: 0.025 kg)) and degraded rapidly in both solutions. Hot pressed materials yielded much higher strength (up to 250 MPa) and microhardness (up to 65 HV (load: 0.025 kg)), and the electrochemical characteristics were significantly better when compared to the cold compacted samples. Temperatures of 300 °C and 400 °C and high compacting pressures from 300 MPa to 500 MPa had a positive influence on material bonding, mechanical and electrochemical properties. A compacting temperature of 500 °C had a detrimental effect on material compaction when using pressure above 200 MPa.

Powder Metallurgy

Brittleness

10.3390/met7110461

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Citations (28)

evolution of microstructure of magnesium materials prepared by SPS using various compacting pressures

Metal ... (2022)

Roman Brescher Michaela Hasoňová Matěj Březina Stanislava Fintová Pavel Doležal

Compacting pressure applied during the SPS method varies in the literature.This study evaluates the influence of the applied compacting pressure on the microstructure and porosity of sintered materials.Using spark plasma sintering (SPS), cold compacted magnesium powder (green compacts) was sintered to bulk magnesium materials.The green magnesium compacts were prepared at room temperature using 100 MPa of uniaxial pressure, which was applied for 60 s.Using SPS, the green compacts sintering was carried out at 400 °C for 10 min.Various compacting pressures were applied during sintering: 20, 40, 60, 80 and 100 MPa to analyse the influence of the pressure.The resulting microstructure and porosity strongly depended on the compacting pressure applied during SPS.An increase of the compacting pressure was shown to be beneficial for material homogeneity, while this effect was pronounced up to 60 MPa, and only a slight effect on the material porosity was observed above this pressure.

Spark Plasma Sintering

10.37904/metal.2022.4500

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Structure and growth kinetic of unconventional fluoride conversion coating prepared on wrought AZ61 magnesium alloy

Surface and Coatings Technology (2020)

Juliána Drábiková Stanislava Fintová Petr Ptáček Ivo Kuběna Matěj Březina

Conversion coating

Arrhenius plot

10.1016/j.surfcoat.2020.126101

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Citations (15)