The study of initial permeability temperature dependences for LiTiZn ferrite ceramics

Results of obtaining and analyzing the temperature dependences of initial permeability of ferrite ceramics are presented in the paper. It was shown that the level of the defective state of ferrite ceramics can be obtained from the value of two parameters [alpha] and [beta] of the phenomenological expression describing the experimental dependences. The results showed that the main criterion of the defect state is the parameter [beta]/[alpha], which is related to the elastic stresses in the material. An indicator of the structure perfection is also the value of the maximum of the initial permeability near the Curie temperature

Effect of particle size on the diffuse reflection coefficient of titanium dioxide powder

In the present work a model of light scattering is shown which explains the result about effect of particle size on the diffuse reflection coefficient of initial titanium dioxide powders. The diffuse reflection coefficient depending on particle size for TiO2 pigment varies on the curve with maximum. The experimental results and the model can be used for technology development of manufacturing pigment for light-reflecting temperature-control coatings of spacecraft

Estimation of thermomagnetometry method sensitivity for magnetic phase determination

In this article, the sensitivity of thermomagnetometry method for magnetic phase determination in lithium substituted ferrites was estimated by thermogravimetric analysis in magnetic field of lithium-zinc ferrite and iron dioxide (Li[0.4]Fe[2.4]Zn[0.2]O[4]+[alpha]-Fe[2]O[3]) components mixture with different mass proportions: 2, 4, 6, and 100 mass% Li[0.4]Fe[2.4]Zn[0.2]O[4] phase in total mixture. Thereby, analyzed samples are mixture of magnetic and nonmagnetic phases. Results of thermomagnetometric analysis were supplemented with the X-Ray diffraction analysis data. It was shown that the thermomagnetometry method allows to determine a magnetic phases with mass content not less than 2 mass% in analyzed mixture. In this case, we can clearly estimate the position and intensity of the peak on derivative thermogravimetric curve, which connected with a magnetic phase transition in ferrite at Curie temperature

STRUCTURE AND PROPERTIES OF FINE-GRAINED Zn-Mg ALLOYS FOR MEDICAL PURPOSES

В работе исследовано влияние условий отливки слитка на структуру и свойства бинарных модельных Zn-Mg сплавов. Установлено, что за счет изменения величины переохлаждения на фронте кристаллизации происходит уменьшение объемной доли эвтектики ((Zn) + Mg2Zn) и измельчение зёренной структуры сплавов в 3-5 раз. Показано, что увеличение содержания Mg в сплаве также способствует измельчению зеренной структуры и увеличению твердости сплавов. Выявлено, что твердость исследованных образцов в большей степени определяется объемной долей эвтектики, а не дисперсностью зеренной структуры сплавов.The influence of ingot casting conditions on the structure and properties of binary model Zn-Mg alloys is investigated. It was found that due to the different magnitude of supercooling at the crystallization front, the volume fraction of eutectic ((Zn) + Mg2Zn) and the alloys grain sizes decreased. It is shown that an Mg content increase in the alloy also provided the grinding of the grain structure and an increase in the alloys hardness. It is revealed that the samples hardness is determined to a greater extent by the volume fraction of the eutectic, and not by the dispersion of the alloys grain structure

3D Fracture Modeling and Fracture-Height Mapping Using Different Logging Methods in the Vertical Well

Abstract Modeling the correct fracture geometry in hydraulic fracturing simulators is challenging. Mapping the fracture can reduce the degree of uncertainty and help adjust the hydraulic fracturing model in the simulator. To map fracture height, acoustic or temperature logging can be used, as well as pulsed-neutron logging combined with tagged nonradioactive tracer (NRT) neutron-absorbing proppant. This article compares the data for modeling a hydraulic fracture in pseudo three-dimensional (P3D) and full 3D (F3D) hydraulic fracturing simulators with the results of studies of mapping fracture height in a well. Analysis of well survey data allowed assessment of the degree of fracture penetration from an oil reservoir through a clay barrier in an aquifer. Interpretation of cross-dipole acoustic logging, which characterizes impaired continuity of the medium, coincides with the interpretation of dual-burst thermal-decay time log (DBTDT) data, reflecting NRT proppant placement in hydraulic fractures near the wellbore. Bottomhole pressure analysis and comparison of production before and after hydraulic fracturing also confirm fracture height measured using two methods: F3D and P3D modeling. The experiment showed that F3D modeling more accurately calculates fracture height than P3D modeling. The interpretation of temperature logging does not correspond to the fracture model and is not supported by other logging methods; therefore, this type of logging cannot be used to adjust fracturing design models.</jats:p