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Danilenko I.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Glazunov F.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Konstantinova T.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Volkova G.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Burkhovetski V.,Donetsk Institute for Physics and Engineering NAS of Ukraine
Journal of the European Ceramic Society | Year: 2013

We have studied the effect of NiO on the sintering of yttria-stabilized zirconia at temperatures ranging from 1300°C to 1500°C in air and argon environments. It was found that the addition of NiO stabilized the cubic phase of ZrO2 independently from the sintering atmosphere. The monoclinic phase of ZrO2 formed only during sintering within the air environment at temperatures higher than 1450°C. The transformation of NiO to Ni by reversible decomposition depends on the sintering atmosphere, and this can lead to variations in the nature of inclusions and in changes of the structure and properties of nanocomposite materials in the system ZrO2-NiO(Ni). NiO and Ni inclusions can increase the indentation fracture toughness of zirconia-nickel oxide composite material more than 50%, which can be compared with zirconia ceramics during sintering in a neutral atmosphere alone. © 2013 Elsevier Ltd. Source


Danilenko I.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Glazunov F.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Konstantinova T.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Yashchyshyn I.,Donetsk Institute for Physics and Engineering NAS of Ukraine | And 2 more authors.
Advanced Materials Letters | Year: 2014

The structure formation of yttria stabilized zirconia - nickel oxide composites sintered in air and argon atmosphere were studied. It was shown that the crack propagation in 3Y-TZP ceramics greatly inhibited by creation of composite structure by addition of NiO particles and sintering at 1500°C in argon atmosphere. Prevention of formation of the monoclinic phase of zirconia was conditioned by sintering composite under argon. Increasing of K1C value was found as in sample shell as in sample core of composite, in comparison with matrix 3Y-TZP ceramics. The increasing of K1C value of obtained intergranular type of composite structure cannot be explained by crack deflection and crack bridging processes by Ni and NiO particles, respectively. The possible explanation of K1C value increasing is the intensification of phase transformation toughening of zirconia by formation of metastable tetragonal phase depleted by Y3+ ions. The reversibly dissociation of NiO on Ni and oxygen in neutral atmosphere provided the formation of cubic phase and Y3+ depleted tetragonal phase. Internal oxidation of Ni during cooling leads to formation metastable tetragonal phase in depleted Y3+ zirconia grains. The formation of NiO particles during cooling lead to emergence of large compressive stresses, which also increased the metastability of tetragonal zirconia grains, depleted of Y3+ ions. © 2014 VBRI press. Source


Danilenko I.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Prokhorenko S.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Konstantinova T.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Ahkozov L.,Donetsk Institute for Physics and Engineering NAS of Ukraine | And 2 more authors.
World Journal of Engineering | Year: 2014

The use of ceramic instead of metallic parts in devices that operate in aggressive conditions increases the service life of machines and equipment for chemical, metallurgical and other industries. The wear resistant zirconia/alumina composites were sintered from nanopowders obtained by co-precipitation technique. In the case of addition of 1wt% of alumina in zirconia ceramics the wear resistance increased by approximately 30%.The formation of complex multilevel composite structures, such as Al3+ ion segregation on zirconia grain boundaries and intracrystalline alumina inclusions in zirconia grains, increased the fracture toughness values of composites obtained from co-precipitated nanopowders and consequently decreased the volume loss of ceramic material.In this study, we investigated the effect of nanopowders synthesis methods and alumina concentration on composite structure, fracture toughness and tribological behavior of 3Y-TZP/alumina ceramic composites and searched correlation between structures and mechanical properties. Source


Danilenko I.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Konstantinova T.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Gorban O.,Donetsk Institute for Physics and Engineering NAS of Ukraine | Volkova G.,Donetsk Institute for Physics and Engineering NAS of Ukraine | And 3 more authors.
NANOCON 2010 - 2nd International Conference, Conference Proceedings | Year: 2010

In this study we investigate the influence of precursor type, synthesis conditions and dopants concentration on phase composition, particle size and agglomeration degree of different oxide nanopowders, in particular: zirconia, zirconia composites, lanthanum manganite, ets. Also we try to find the influence of characteristics of these powders on consolidation. It was shown that the synthesis conditions have extremely influence on characteristics and structure of different types of oxide nanopowders. In case of zirconia the change of synthesis conditions lead to changing the particle size, agglomeration degree and particle surface properties. Consolidation of nanoparticles under high pressure conditions lead to martensitic phase transformations and this process has extremely depends from synthesis conditions. Zirconia nanopowders which are synthesized from nitrate salts are more stable to phase transition in comparison with powders obtained from chloride salts. For LSM materials we found the strong difference of particles morphology and magnetic properties according to starting material structure. It was found that formation of complex structure of precursor materials during drying and calcinations stage do not allow to obtain the nanoparticles. It was shown that the powders characteristics, what formed during synthesis, are inherited during consolidation process and in ceramics structure and properties. © 2013 TANGER Ltd. Source

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