On the formation of AlSiMgCu/quasicrystal powder composite single tracks by selective laser melting

The process of selective laser melting (SLM) of an Al-Si-Mg-Cu powder composite with the addition of quasicrystal reinforcements under conditions of a limited powder amount was investigated. The morphology and microhardness of the obtained scan single tracks were discussed, and the optimal sintering parameters were found to be in the Linear Energy Density (LED) range 0.21-0.30 J/m

ВЛИЯНИЕ РЕЖИМОВ ОКИСЛЕНИЯ НА ХАРАКТЕРИСТИКИ МОП-КОНДЕНСАТОРОВ С НАНОКРИСТАЛЛАМИ Ge

A 2D layer of spherical, crystalline Ge nanodots embedded in a SiO2 layer was formed by low pressure chemical vapor deposition combined with furnace oxidation and rapid thermal annealing. The samples were characterized structurally by using transmission electron microscopy in plan-view and cross-section geometries. It was found that the formation of highdensity Ge dots took place due to oxidation induced by the Ge segregation. Electrical properties were controlled by measuring C–V and I–V characteristics after the formation of MOS capacitors in different oxidation conditions and the ambient medium. A strong evidence of the charge storage effect on the crystalline Ge-nanodot layer was demonstrated by the hysteresis behavior of the high-frequency C–V curves. It is shown that dry oxidation followed by its reduction increases the hysteresis value compared to wet oxidation conditions. This hysteresis behavior is discussed taking into account the decrease in the Ge concentration and a possible effect of low temperature GeO evaporation is followed by wet oxidation. Проведены исследования структуры и электрофизических характеристик МОП-конденсаторов, сформированных путем термического окисления в различных режимах тонких слоев SiGe сплавов на туннельном диэлектрике. Методом просвечивающей электронной микроскопии показано формирование нанокристаллов Ge и обнаружено влияние режимов окисления на структуру слоев SiO2 . С помощью измерений высокочастотных вольт-фарадных и вольт-амперных характеристик изучены электрические свойства МОП-структур и показано, что они обладают гистерезисом вольт-фарадных характеристик, а его величина существенно зависит от режима и атмосферы термообработок. Качество сформированных МОП-структур улучшается при использовании окисления в сухом кислороде с учетом оптимальной длительности окисления пленки SiGe, что подтверждается данными вольт-амперных характеристик. Полученные результаты обсуждаются с учетом возможного механизма удаления Ge из слоя SiO2 за счет низкотемпературного испарения монооксида германия (GeO)

PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE INSOLUBLE RESIDUE OF HYDRANIC ACID LEACHING OF URANIUM FROM SLUDGE

Leaching of sludge by solutions of 120-160 gL-1 HCl at 80 °C provides a decrease in the mass of insoluble residue in 2-3 times. The moisture content is 12-26% the average particle diameter is 60-100 μm. The insoluble residue consists of CaSO4*2H2O, CaF2, graphite and two modifications of SiO2

LEACHING OF URANIUM FROM SOLID RADIOACTIVE WASTE BY HYDROCHLORIC ACID SOLUTIONS

The maximum degree of uranium extraction of 99% was obtained by HCl an excess con-centration of more than 74 gL-1, the uranium content in the PR is 255 mgL-1. According to the results of XRD, the insoluble residue of leaching consists of CaSO4*2H2O 62-84%, CaF2 10-31%, graphite 3-7% and SiO2 1-5%

URANIUM SORPTION FROM PREGNANT SOLUTIONS OF SLUDGE CARBONATE LEACHING

The possibility of uranium recovery from pregnant solutions of sludge carbonate leaching by strong basic anion-exchangers was studied. Sorption of U by resins in carbonate and chlo-ride forms was not effective, and residual content of uranium in liquid phase after sorption was high

KINETIC OF SORPTION OF SCANDIUM AND IMPURITIES FROM HYDROLISIS SULFURIC ACID BY AMPHOLYTE PUROLIE S950

The kinetic of sorption of Sc, Zr, Al, Th, Ti and Fe from the hydrolysis sulfuric acid by using ampholyte Purolite S950 was investigated. The limiting stage of sorption of Sc and Zr was internal diffusion, and the sorption of Ti, Al, Fe and Th was carried out in a mixed-diffusion mode

The adsorptive-kinetic model of in-situ phosphorus doped film polysilicon deposition process

The investigation of deposition kinetics of in-situ phosphorus doped polysilicon films has been performed. The adsorptive-kinetic model of in-situ phosphorus doped polysilicon deposition has been developed. The values of heterogeneous reaction constants and constants, which describe the desorption process for monosilane and phosphine, have been defined. The optimal process conditions, which provide the acceptable deposition rate, thickness uniformity, high doping level and conformal step coverage, have been founded

The deposition of silicon nitride films under low pressure on wafers up to 200 mm

The influence of silicon nitride deposition condition on parameters of the obtained films has been investigated. It has been found that the deposition rate of silicon nitride films decreases with deposition temperature decreasing, and at the same time the within wafer thickness uniformity improves. It allows performing the reproducible deposition of silicon nitride films with thickness of less than 10 nm. It has been found that in order to decrease the oxidation depth of silicon nitride, it is appropriate to carry out the oxidation under 850—900°C. The developed process of silicon nitride deposition made it possible to obtain reservoir capacitors with specific capacitance of 3,8—3,9 fF/μm2 at film thickness of 7,0 nm

AlSi10Mg/AlN Interface Grain Structure after Laser Powder Bed Fusion

Details and features of the grain structure near the interface region between the AlN ceramic phase and AlSi10Mg matrix after the laser powder bed fusion (LPBF) were investigated. Aluminum nitride particles were obtained through self-propagating high-temperature synthesis and mechanically mixed with aluminum matrix powder. Optimization of the LPBF process parameters resulted in synthesized material free of pores and other defects. Optical microscopy analysis of etched cross-section and more detailed EBSD analysis revealed regions with relatively coarse grains at melting pool boundaries and fine grains in the melt pool core and near the AlN particles. Moreover, a pronounced orientation of fine elongated matrix grains towards the center of the ceramic particle was obtained. The such formed microstructure is attributed to directional heat sink during crystallization due to the higher thermal conductivity of aluminum nitride compared to the AlSi10Mg matrix. On the contrary, poor wettability of AlN by melt partly prevented the formation of such features, thus a combination of these factors determines the final microstructure of the interface in the resulting material

AlSi10Mg/AlN Interface Grain Structure after Laser Powder Bed Fusion

Details and features of the grain structure near the interface region between the AlN ceramic phase and AlSi10Mg matrix after the laser powder bed fusion (LPBF) were investigated. Aluminum nitride particles were obtained through self-propagating high-temperature synthesis and mechanically mixed with aluminum matrix powder. Optimization of the LPBF process parameters resulted in synthesized material free of pores and other defects. Optical microscopy analysis of etched cross-section and more detailed EBSD analysis revealed regions with relatively coarse grains at melting pool boundaries and fine grains in the melt pool core and near the AlN particles. Moreover, a pronounced orientation of fine elongated matrix grains towards the center of the ceramic particle was obtained. The such formed microstructure is attributed to directional heat sink during crystallization due to the higher thermal conductivity of aluminum nitride compared to the AlSi10Mg matrix. On the contrary, poor wettability of AlN by melt partly prevented the formation of such features, thus a combination of these factors determines the final microstructure of the interface in the resulting material