Statistics and Thermodynamics of Fe-Cu Alloys at High Temperatures

Statistics and thermodynamics of binary Fe-Cu system is described in terms of local state representation combined with the account of nonergodic microheterogeneity in terms of frozen fluctuations of chemical potential. It is shown that the microheterogeneity in this system is an equilibrium property up to 1700° C

Optical properties and structure particularities of LiNbO3 crystals grown from a boron-doped melt

A series of LiNbO3:B crystals was grown from the melt doped by boron. It is shown that LiNbO3:B crystals possess an increased resistance to optical damage. We have found changes according to Raman spectra confirming the ordering of Li+, Nb5+ cations and vacancies along the polar axis. The chemical interactions were studied in the system Li2O–B2O3–Nb2O5. Boron cations are unable to incorporate into a cation sublattice of LiNbO3, but they change the physic-chemical structure of a melt. It contributes to an increased structure and optical uniformity of LiNbO3:B.Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

ВОССТАНОВЛЕНИЕ И УПРОЧНЕНИЕ ПЛУНЖЕРНЫХ ПАР ТОПЛИВНЫХ НАСОСОВ ВЫСОКОГО ДАВЛЕНИЯ

The character and wear values of plunger pairs of high-pressure fuel pump is described. Plunger pairs of diesel fuel pumps work in conditions of high loadings and considerable wear. Plunger and sleeve precision surfaces are subjected to various types of wear, abrasive one being prevail. Geometrical parameters of the parts leading to the decrease in cyclic fuel supply, hydraulic density, change of the intake angle and others are varied. Methods of plunger pair restoration and hardening by means of high hardness coating on the precision surface are analyzed and compared. Technological process of carbide-chrome coating by virtue of diffusive chromium plating (vacuum and gas method) of a plunger and a sleeve made of steels ХВГand 25Х5М is described. Special features of plunger and sleeve machining are described. To increase capability and restoration of plunger pairs of high-pressure fuel pumps a method of diffusive chromium plating is proposed. The latter means that the parts are covered with a layer of hard coating. This results not only in hardening parts but also in compensating for their wear.Purpose – to determine methods of plunger pair restoration and hardening by virtue of high hardness coating on the precision surface.Method and techniques – technological process of carbide-chrome coating by virtue of diffusive chromium plating (vacuum and gas method) of a plunger and a sleeve made of steels ХВГand 25Х5М is given.Results: capability and restoration of high-pressure fuel pump plunger pairs are increased by using a method of diffusive chromium plating.Field of result application: it makes sense to use the results obtained to increase capability and restoration of high-pressure fuel pump plunger pairs.Описывается характер и величины износов плунжерных пар топливного насоса высокого давления. Плунжерные пары топливных насосов дизеля работают в условиях высоких нагрузок и значительного изнашивания. Прецизионные поверхности плунжера и гильзы подлежат различным видам изнашивания, среди которых преобладает абразивный износ. Изменяются геометрические параметры деталей, приводящие к снижению цикловой подачи топлива, гидравлической плотности, изменению угла впрыска и других показателей. Характеризуются и сравниваются методы восстановления и упрочнения плунжерных пар путем образования на прецизионной поверхности покрытия высокой твердости. Описывается технологический процесс нанесения карбиднохромового покрытия путем диффузионного хромирования (вакуумным и газовым способами) плунжера и втулки из сталей ХВГ и 25Х5М. Описываются особенности механической обработки плунжера и втулки. Для повышения ресурса и восстановления плунжерных пар топливных насосов высокого давления предлагается использовать метод диффузионного хромирования, при котором на детали наносится слой твердого покрытия, позволяющий помимо упрочнения деталей компенсировать их износ.Цель – определение методов восстановления и упрочнения плунжерных пар путем образования на прецизионной поверхности покрытия высокой твердости.Метод или методология проведения работы: в статье приведен технологический процесс нанесения карбиднохромового покрытия путем диффузионного хромирования (вакуумным и газовым способами) плунжера и втулки из сталей ХВГ и 25Х5М.Результаты: повышен ресурс плунжерных пар топливных насосов высокого давления использованием метода диффузионного хромирования, позволяющий помимо упрочнения деталей компенсировать их износ.Область применения результатов: полученные результаты целесообразно применять для повышения ресурса и восстановления плунжерных пар топливных насосов высокого давления

Admittance of MIS structures based on graded-gap MBE HgCdTe with Al2O3 insulator

The paper presents the results of studies of the admittance of MIS structures based on heteroepitaxial MBE n (p)-Hg0.78Cd0.22Te with insulator coating SiO2/Si3N4 and Al2O3 in the test signal frequency range 10 kHz-1 MHz at temperatures ranging from 8 to 220 K. The main parameters of MIS structures with different insulators were determined. MIS structures with Al2O3 have a large enough insulator capacitance (compared to SiO2/Si3N4), a significant modulation capacitance on the CV characteristics, high dielectric strength and low values of the flat-band voltage. The effective charge density found from the value of the flat-band voltage and slow interface trap density for structures with Al2O3 comparable with the corresponding densities for structures with SiO2/Si3N4

Impact of the graded-gap layer on the admittance of MIS structures based on MBE-grown n-Hg1-xCdxTe (x = 0.22-0.23) with the Al2O3 insulator

The impact of the presence of the near-surface graded-gap layers with an increased content of CdTe on the admittance of MIS structures based on MBE-grown n-Hg1–xCdxTe (x = 0.22–0.23) with the Al2O3 insulating coating has been experimentally studied. It has been shown that the structures with a gradedgap layer are characterized by a deeper and wider capacitance dip in the low-frequency capacitance–voltage (CV) characteristic and by higher values of the differential resistance of the space-charge region than the structures without such a layer. It has been found that the main features of the hysteresis of capacitance dependences typical of the graded-gap structures with SiO2/Si3N4 are also characteristic of the MIS structures with the Al2O3 insulator. The factors that cause an increase in the CV characteristic hysteresis upon formation of the graded-gap layer in structures with SiO2/Si3N4 or Al2O3 are still debatable, although it may be assumed that oxygen plays a certain role in formation of this hysteresis

Unipolar barrier structures based on HgCdTe for infrared detection

One of the topical areas of solid state photoelectronics is the creation of infrared detectors based on unipolar barrier systems (for example, with an nBn architecture). The greatest progress has been achieved in the development of barrier detectors based on semiconductors of the AIIIBV group, which is associated with the possibility of realizing systems with a zero barrier in the valence band. Unipolar barrier detectors based on mercury cadmium telluride (HgCdTe) grown by molecular beam epitaxy (MBE) are of interest due to significant technological advantages, since the creation of such devices can abandon the defect forming procedure of ion implantation. Despite a significant number of theoretical works, only a few attempts are known to practically implement nBn detectors based on MBE HgCdTe