Glass and Ceramics Ltd.

Saint Petersburg, Russia

Glass and Ceramics Ltd.

Saint Petersburg, Russia
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Kurapova O.Yu.,Saint Petersburg State University | Konakov V.G.,Saint Petersburg State University | Grashchenko A.S.,Russian Academy of Sciences | Novik N.N.,Saint Petersburg State University | And 2 more authors.
Reviews on Advanced Materials Science | Year: 2017

This paper addresses fabrication, structure, and hardness characteristics of nanotwinned (ntw) copper-graphene composites. The composites were fabricated by electrodeposition from 1M CuSO4·6H2O mixed water-alcohol solution containing graphene-graphite mixture stabilized by non-ionic surfactant. We fabricated two-layer solids each consisting of ntw copper layer and ntw copper-graphene layer. The synthesized two-layer specimens were examined in nanoindentation tests and showed high hardness values up to 3 GPa. The maximum hardness value of 3 GPa is higher than those of pure ntw copper and copper-graphene composites, taken from the literature. © 2017 Advanced Study Center Co. Ltd.


Archakov I.Yu.,Russian Academy of Sciences | Kazykhanov V.U.,RAS Institute for Metals Superplasticity Problems | Konakov V.G.,Saint Petersburg State University | Kurapova O.Yu.,Saint Petersburg State University | And 5 more authors.
Reviews on Advanced Materials Science | Year: 2017

This paper presents data on fabrication of "nickel-graphene-graphite" bulk composites using powder metallurgy methods combined with the high energy ball milling. The composites were then processed by high pressure torsion (HPT) at temperatures of 23 and 200°C. This treatment gives rise to the formation of new "nanostructured nickel-graphene" composites. The phase composition of the new composite specimens was examined by X-ray diffraction. Raman spectroscopy proved graphite-to-graphene conversion under mechanical treatments. The microstructure of the new composite specimens was investigated by scanning electron and transmission electron microscopy methods. Composite specimens after HPT at temperature of 200°C demonstrate the optimal combination of strength (σ02= 923 MPa; σb= 992 MPa) and ductility (δ = 99%). Composite specimens with 2 wt.% graphene content after HPT at room temperature exhibits superior microhardness Hv = 6.45 GPa. © 2017 Advanced Study Center Co. Ltd.


Kurapova O.Yu.,Saint Petersburg State University | Golubev S.N.,Glass and Ceramics Ltd. | Ushakov V.M.,Glass and Ceramics Ltd. | Konakov V.G.,Saint Petersburg State University
Reviews on Advanced Materials Science | Year: 2017

The work reports the detailed investigation of factors affecting crystallization and phase stability of nanosized precursors based on zirconia solid solutions obtained by reversed co-precipitation technique from diluted salts solution and further dehydration (freeze-drying, freeze-drying with glycerol, freezing in liquid nitrogen, drying under overpressure). Basing on simultaneous thermal analysis (STA) data, the criterion for crystallization completeness of the "amorphous phase → crystalline solid solution" transition was suggested. Consideration of STA and X-Ray diffraction technique (XRD) results provides an opportunity to state that freeze-drying favors step character of precursor crystallization, while the use of freezing in liquid nitrogen leads to single step crystallization. Combining XRD results with the data of particle size distribution analysis, it was shown that phase stabilization of cubic zirconia based solid solution at temperatures up to 1000°C is due to the fine powder dispersity in that temperature region. © 2017 Advanced Study Center Co. Ltd.


Konakov V.G.,Saint Petersburg State University | Kurapova O.Yu.,Saint Petersburg State University | Lomakin I.V.,Saint Petersburg State University | Novik N.N.,Saint Petersburg State University | And 4 more authors.
Reviews on Advanced Materials Science | Year: 2017

The present work reports the detailed investigation of graphene-modified bulk nickel composites with graphene+graphite phase content up to 4.7 at.%. The composites were fabricated using ball milling and powder metallurgy methods with nickel nanopowder and exfoliated graphite being starting materials. Phase composition and composites structure were studied via X-ray diffraction technique (XRD), Differential scanning calorimetry (DSC), Raman spectroscopy (RS) and scanning electron microscopy (SEM). The effect of graphene addition on the grains size and orientation was determined from backscattered electrons images (EBSD technique). The effect of graphene-graphite phase content on the mechanical properties of the composite was studied. It was shown that small amounts of this phase result in the graphene formation on the surface of metal grains; in turn, this phenomenon affects the composite mechanical properties: its hardness increases, its plasticity decreases, and the strength value remains on the same level. The increase in the graphene-graphite phase content results in graphene flakes formation and new phase allocation corresponding to graphite, leading to the plasticity recovery and in the significant decrease of hardness and strength. © 2017 Advanced Study Center Co. Ltd.


Konakov V.G.,Saint Petersburg State University | Kurapova O.Yu.,Saint Petersburg State University | Arutyunyan A.R.,Saint Petersburg State University | Lomakin I.V.,Saint Petersburg State University | And 3 more authors.
Materials Physics and Mechanics | Year: 2016

Ni - 1 wt.% Y2O3-92ZrO2 (YSZ) composite is fabricated by powder metallurgy technique with subsequent annealing at 1250 °C. Both the presence of ceramic nanopowder inclusions in the composite and identity of the compositions specifying the final phase and the initial mixture are revealed by energy dispersive analysis. With scanning electron microscopy, the microstructure of the composite is examined, and its typical grain size is estimated. The mechanical tests of the composite are performed addressing both tension of flat specimens and compression of cylindrical specimens. The optimal techniques for the further cyclic tests of Ni - 1 wt.% YSZ are proposed according to the standardized tests (GOST 25.502-79). © 2016, Institute of Problems of Mechanical Engineering.


Konakov V.G.,Saint Petersburg State University | Solovyeva E.N.,Glass and Ceramics Ltd. | Kurapova O.Y.,Saint Petersburg State University | Novik N.N.,Saint Petersburg State University | And 2 more authors.
Materials Physics and Mechanics | Year: 2015

The approach for "nickel-YSZ-nanoceramics" bulk nanocomposite synthesis was developed. Compositions with the nanoceramic phase content lying in the range up to 20 wt.% YSZ were manufactured; their structure and chemical composition were studied using XRD, SEM, and EDX techniques. Experimental study of the composite mechanical properties (compressive strength) as a function of sample composition demonstrated the existence of maximal composite strength at YSZ content of 3 wt.%. Further addition of nanoceramic phase resulted in the significant decrease in material strength. © 2015 Institute of Problems of Mechanical Engineering.


Konakov V.G.,Saint Petersburg State University | Ovid'ko I.A.,Saint Petersburg State University | Solovyeva E.N.,Glass and Ceramics Ltd. | Kurapova O.Y.,Saint Petersburg State University | And 2 more authors.
Materials Physics and Mechanics | Year: 2015

The paper reports synthesis of bulk nanocomposites from nanosized nickel and yttrium-stabilized zirconia powders. Characteristics of the phase composition of the synthesized composites and their microstructure are experimentally revealed. Mechanical properties of the composites are experimentally measured and discussed as those depending on the nanoceramic phase content. With the experimental data, it is concluded that the mechanical strength of the nanocomposites remains high enough in a wide range of nanoceramic phase concentrations. © 2015 Institute of Problems of Mechanical Engineering.


Konakov V.G.,Saint Petersburg State University | Kurapova O.Y.,Saint Petersburg State University | Novik N.N.,Saint Petersburg State University | Golubev S.N.,Glass and Ceramics Ltd.
Materials Physics and Mechanics | Year: 2015

The approach for "copper-graphene" composites electrochemical deposition using graphene suspensions stabilized by non-ionic surfactants (polyacrylic acid and pluronic F-127) was developed. The produced coatings were studied by SEM and XRD. As a result, graphene and surfactant contents were optimized to achieve high quality of the composite surface. It has been shown that the type of non-ionic surfactant highly affects composite microstructure and its crystallinity. © 2015 Institute of Problems of Mechanical Engineering.


Konakov V.G.,Saint Petersburg State University | Kurapova O.Yu.,Saint Petersburg State University | Lomakin I.V.,Saint Petersburg State University | Archakov I.Yu.,Russian New University | And 2 more authors.
Reviews on Advanced Materials Science | Year: 2016

This paper addresses nanoengineering approaches developed to synthesize metal the synthesized nanocomposites. With the experimental data on their microstructure, phase composition, thermal, and mechanical characteristics, we discuss the effects of nanoinclusions on the properties exhibited by these nanocomposites. Optimized synthesis technologies are suggested which allow one to fabricate metal-ceramic and metal-graphene nanocomposites with desired structures and properties. © 2016 Advanced Study Center Co. Ltd.


Konakov V.G.,Saint Petersburg State University | Kurapova O.Yu.,Saint Petersburg State University | Novik N.N.,Saint Petersburg State University | Pivovarov M.M.,Glass and Ceramics Ltd. | Archakov I.Yu.,Saint Petersburg State University
Reviews on Advanced Materials Science | Year: 2015

An approach providing yttrium-stabilized zirconia coatings deposition on titanium is suggested. High-quality YSZ coatings with 5-6 μm thickness were studied using SEM and XRD, the mechanical properties (Brenell and Moos hardness) of covered samples were compared with pure titanium characteristics. The regimes of titanium wafer pretreatment were optimized. It was shown that both 8Y2O3-92ZrO2 and 9Y2O-10TiO2-92ZrO2 coatings increase the material hardness. © 2015 Advanced Study Center Co. Ltd.

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