PRECISION CASTING INTO DISPOSABLE CERAMIC MOLD – A HIGH EFFICIENCY METHOD OF PRODUCTION OF CASTINGS OF IRREGULAR SHAPE

The article shows the advantages and disadvantages of precision casting into disposable ceramic molds. The high quality shaped castings produced by modernized ceramic molding process are proved the reliability and prospects of this advanced technology

Carrier transport in porous-SiNic-Si nanostructures

In the present paper we have studied the peculiarities of carrier transport properties of nanoheterostructures containing silicon substrate covered with porous silicon layer, where pores were either filled or non-filled with ferromagnetic Ni clusters.We have carried out DC conductivity experiments as a function of temperature (ranging from 2 to 300 K) and porosity of porous silicon layer (between 30% and 70%). Presence of a surface layer with high resistance on the porous silicon top and its role in nanoheterostructure formation was revealed. It was shown that specific electrochemical kinetics of Ni deposition into porous silicon significantly influences resultant nanostructure resistance and high temperature conductance activation energy

Кристаллическая и магнитная структуры твердых растворов на основе BiFeO3

The correlation between the multiphase state of the system and its magnetic properties was studied on Bi1–xEuxFeO3 ceramic samples in the range 0.12 ≤ x ≤ 0.18. The X-ray diffraction results indicate that, with an increase in the concentration of Eu ions, a structural transition from the rhombohedral (R3c) to nonpolar orthorhombic (Pnma) phase is observed through the partial formation of an antipolar orthorhombic structure (Pbam). The mixed phase state in the obtained compounds is observed in the range 0.12 ≤ x ≤ 0.16. Magnetic measurements in a strong magnetic field indicate a weak ferromagnetic interaction. The magnetic response in a strong field is explained by the location of the spins at the phase boundary, as well as by the presence of intrinsic antiferromagnetic spins.Исследование корреляции между многофазным состоянием системы и ее магнитными свойствами было проведено на керамических образцах Bi1-xEuxFeO3 с 0,12 ≤ x ≤ 0,18. Результаты рентгеновской дифракции свидетельствуют о том, что с увеличением концентрации ионов Eu наблюдается структурный переход от ромбоэдрической (R3c) к неполярной орторомбической (Pnma) фазе через частичное образование антиполярной орторомбической структуры (Pbam). Смешанное фазовое состояние в полученных соединениях наблюдается в интервале 0,12 ≤ x ≤ 0,16. Магнитные измерения в сильном магнитном поле указывают на слабое ферромагнитное взаимодействие. Магнитный отклик в сильном поле объясняется расположением спинов на фазовой границе, а также наличием собственных антиферромагнитных спинов

Fabrication and properties of porous silicon – iron magnetic nanocomposites

Porous silicon (PS)/Fe nanocomposites were fabricated by electrochemical deposition of Fe into pores of mesoporous silicon template under the stationary galvanostatic regime. Magnetic properties of PS/Fe nanocomposite were investigated by measuring the temperature dependence (77 – 700 K) of the specific magnetization (T) dependencies allowed us to determine the Curie temperature, Tc, which is very close to of the Curie temperature of the bulk Fe. A crystalline of the PS/Fe nanocomposites was studied by XRD. No peaks corresponded to Fe oxides are revealed on the XRD patterns

USE OF TECHNOLOGY OF PRECISION CASTING INTO DISPOSABLE CERAMIC MOLD FOR PRODUCTION OF SHAPED CASTINGS AND OF CASTINGS WITH THE HIGHER PERFORMANCE REQUIREMENTS

Through the example of production of specific castings the effectiveness of the precision ceramic molding technology for the production of shaped castings and castings with the higher performance requirements has been demonstrated

Carrier transport in porous-Si/Ni/c-Si nanostructures

In the present paper we have studied the peculiarities of carrier transport properties of nanoheterostructures containing silicon substrate covered with porous silicon layer, where pores were either filled or non-filled with ferromagnetic Ni clusters. We have carried out DC conductivity experiments as a function of temperature (ranging from 2 to 300 K) and porosity of porous silicon layer (between 30% and 70%). Presence of a surface layer with high resistance on the porous silicon top and its role in nanoheterostructure formation was revealed. It was shown that specific electrochemical kinetics of Ni deposition into porous silicon significantly influences resultant nanostructure resistance and high temperature conductance activation energy

Carrier transport in porous-Si/Ni/c-Si nanostructures

In the present paper we have studied the peculiarities of carrier transport properties of nanoheterostructures containing silicon substrate covered with porous silicon layer, where pores were either filled or non-filled with ferromagnetic Ni clusters. We have carried out DC conductivity experiments as a function of temperature (ranging from 2 to 300 K) and porosity of porous silicon layer (between 30% and 70%). Presence of a surface layer with high resistance on the porous silicon top and its role in nanoheterostructure formation was revealed. It was shown that specific electrochemical kinetics of Ni deposition into porous silicon significantly influences resultant nanostructure resistance and high temperature conductance activation energy

Trends in the use of bentonite clays

The paper gives a general description of the areas of application of bentonite clays. A number of deposits were evaluated in terms of their use in various technological processes. Analysis of directions of application of bentonite clays in foundry was carried out.Using the methods of X-ray and gas chromatographic analysis, scanning electron microscopy, thermogravimetry and direct adsorption-structural measurements, it is shown that materials obtained from montmorillonite and heteronuclear hydroxo complexes Cr-Cu have greater thermal stability and better sorption characteristics compared to montmorillonite fixed by mononuclear hydroxo complexesUsing montmorillonite modified with heteronuclear hydroxo complexes Cr-Cu with the best adsorption-structural parameters and zeolite NCVM, a laboratory batch of mixed adsorbent catalysts has been developed.This material has been studied in deep vapor oxidation processes of low concentrated organic substances such as acetone, toluene, ethyl acetate, ethanol, butanol and butyl acetate.The conversion rate on the mixed adsorbent catalysts for the studied adsorbates was found to be 94.9–97.7 (average 96.2 %)