Development of Scientific Fundamentals for the Conversion of a Virtual Binary Lead Selenide Ferroelectric into a Real Ferroelectric of Lead Selenite for Physico-Chemical Sensors

The scientific basis for the production of a new composite material (1-x)PbSexPbSeO3, where x=0-1, by oxidation with oxygen at temperatures of 500-550 °C and oxidation times of 0.5-4 h from the initial phase of PbSe in the form of powder, film or compact material, having a ferroelectric phase transition in disordered crystals is developed. On the X-ray spectra of the original PbSe samples oxidized at 500°C (oxidation time of 0.5 h) it has been found that the PbSe phase reflexes are predominately present, including the X-ray spectra of the original PbSe samples oxidized at 500 °C (oxidation time of 4 h) - PbSeO3 monoclinic phase reflexes. For all other PbSe oxygen-oxidized samples at temperatures of 500-550 °C and within the time range of 0.5-4 h, X-ray spectra show the simultaneous presence of X-ray reflexes of both phases with the trend of increasing the PbSeO3 phase as the oxidation time increases. Temperature measurements of the DC resistance of the PbSe samples revealed an abnormal change in electrical resistance at the initial oxidation stage for both the film and the compact material, and further oxidation contributed to the capsulation of PbSe grains by the dielectric casing PbSeO3 and the gradual increase in the resistance of the material.

ПРОГНОЗИРУЕМЫЕ ЭФФЕКТЫ УПРОЧНЕНИЯ АЛМАЗНЫМ ВЫГЛАЖИВАНИЕМ ДЕТАЛЕЙ ПОЛУЧЕННЫХ С ПОМОЩЬЮ СЕЛЕКТИВНОГО ЛАЗЕРНОГО СПЕКАНИЯ

The analysis of the possibility of expanding the scope of selective laser sintering technology has been made for the production of parts of short-range gas turbine aircraft engines due to the strengthening of stress concentration points by local plastic deformation by diamond smoothing. The technical, economic, and social effects of the application of this technology have been considered.The stress-strain state of complex-shaped thin-walled parts such as a disk and a monowheel of a short-life aircraft engine during their manufacture according to the traditional techniques from the compact materials VT8 and INCONEL 718 and according to the alternative technology from the materials Ti45Al3Nb (SLS) and INCONEL 718 (SLS)has been calculated and studied. The analysis of stress fields in stress concentration zones is carried out. Estimates are obtained from the static strength reserves of these parts during delamination and rupture of the force layers. A comparison of the obtained reserves of static strength for various places of stress concentration of parts made of compact and non-compact materials has been performed.The effectiveness of the use of alternative technology has been estimated by calculating the unit cost of production in mass production with a production program of 1000 pcs. The economic effect of the use of selective laser sintering and hardening technology in the manufacture of a part of a disk made of INCONEL 718 non-compact material (SLS) is estimated in comparison with the basic technology for the production of a part made of INCONEL 718 compact material in mass production. The comparison of the required capital investments for basic and alternative technology is carried out. The impact of alternative technology on the social and environmental spheres of human life has been assessed.Conclusions have been drawn about the prospects of introducing the technology of local plastic deformation by diamond smoothing to expand the scope of using SLS in the production of parts for the domestic aviation and aerospace industries and society, as well as its potential for other industries.

SEDIMEN DAN MANFAATNYA

SEDIMENT AND ITS BENEFITS. Sediment deposition is a form of compact material that accumulates on the surface or near the surface of the earth, under conditions of low pressure and temperature. Sediment is generally a product of old rock destruction which is transported and distributed by water or wind currents. Sediments are the result of chemical or biochemical precipitation of the solution. Learning the distribution of sediment on the seabed is desperately needed and very useful, for the initial phase to lay the wire and pipe lines on the sea, consider topography of sea (bathimetry), sedimentary texture and ocean currents. Clays are considered unfavorable for the laying of construction pole as a result of clay having a high volume change potential. Clay will undergo expansion when water increases and shrinkage occurs when the water content is less. Rock sediments of sand and limestone are useful for building materials.

Investigation of Thermostressed State of Coating Formation at Electric Contact Surfacing of “Shaft” Type Parts

The forming of coating at electric contact surfacing is considered. The mathematical model of the coating formation is developed. The method of numerical recurrent solution of the finite-difference form of static equilibrium conditions of the selected elementary volume of coating is used. This model considers distribution of thermal properties and geometric parameters along the thermal deformation zone during the process of electric contact surfacing by compact material. It is found that the change of value of speed asymmetry factor leads to increasing of the friction coefficient in zone of surfacing. This provides the forming of the coating of higher quality. The limitation of the technological capabilities of equipment for electric contact surfacing is related to the size of recoverable parts and application of high electromechanical powers. The regulation of the speed asymmetry factor allows for expanding the technological capabilities of equipment for electric contact surfacing. The nomograms for determination of the stress on the roller electrode and the finite thickness of the coating as the function of the initial thickness of the compact material and the deformation degree are shown.

Microstructure Effects in Amorphous and Microcrystalline Ge:H Films

The characterization of void-related microstructure in amorphous and microcrystalline Ge:H films is reported. Various methods are applied including effusion measurements of hydrogen and of implanted helium and neon, measurements of the infrared absorption of C-H bonds due to in-diffusion of contaminants and of the stretching modes of bonded hydrogen. Several microstructure effects like interconnected voids and isolated voids and a quite different material homogeneity are detected and are found to depend on the preparation conditions. Amorphous Ge:H can be prepared with a (largely) homogeneous structure while microcrystalline Ge:H tends to consist of compact grains surrounded by more or less open voids. Enhanced substrate temperatures (Ts ≈ 250°C) favour the growth of more compact material.

Microcellular Polycarbonate with Improved Notched Impact Strength Produced by Injection Moulding with Physical Blowing Agent

Polycarbonate has the reputation of having a tough breaking behaviour, but it is often unknown that this applies only to special conditions. The impact strength of polycarbonate depends on the temperature, the thickness (with a tough brittle transition at thickness increases), contribution of notch tip radius, impact speed, physical blowing agent, molecular weight of the polymer and the processing parameters. Research results indicated that microcellular foams produced by injection moulding with physical blowing agent (MuCell™ Technology by Trexel) shows significant higher notched impact strength than compact polycarbonate, if the compact material is brittle under the same test parameters. However, if the compact polycarbonate breaks toughly, the notched impact strength of the foamed material is always lower. Therefore, it is highly important to pay attention to the test parameters and conditions when comparing the toughness of the foamed with the compact material. The toughness of microcellular foams shows similar properties to PC/ABS and PC/PP blend systems, which provides the possibility to combine the higher impact strength with the advantages of microcellular foaming like weight reduction, lower shrinkage, shorter cycle times, lower clamp forces and reduced melt viscosity. In order to use technologies and conditions which are applied in the polymer industry, all materials were produced by an injection moulding process. Special processing technologies like gas counter pressure and precision mould opening were used in order to reach microcellular foam structures with cell diameters around 10 μm. These technologies yield exactly adjustable foam morphologies. Special morphologies are required to improve the notched impact strength of the foamed material. Two different equivalent models were extracted from the analyses, which indicate significant higher notched impact strength than the compact material under the same test conditions. The knowledge of the ideal foam morphologies enables the industry to produce foamed materials with improved mechanical properties.

UCHII regions in the Antennae

We explore the physical characteristics of young stellar clusters in the Antennae by combining recent ground- and space-based mid-infrared observations with a newly developed set of diagnostic diagrams. Spitzer data give an overview of the star-forming regions extending over hundreds of parsecs, showing a dominant diffuse ISM component with a density of 102 cm−3 plus a small fraction of very compact material (106 cm−3). With its higher spatial resolution VISIR gives a close-up view of the latter component. Its emission line ratios suggest that these regions are fundamentally different from local star-forming regions. Instead of having small isolated UCHII regions, as in local star-forming regions, the average density of the medium of the whole region falls in the (ultra)compact regime, exceeding 104 cm−3 over tens of parsecs.