Papers by Keyword: Phase

Abstract: Tin Oxide (SnO₂) is a metal oxide which has many applications in industry. In this study, SnO₂ powders were synthesized by a self-propagating combustion (SPC) method. The product was annealed at 800 °C for 12 and 24 h before characterizing with X-Ray Diffraction (XRD) for phase studies. X-Ray Diffraction results showed that both samples are pure of tetragonal structure with space group P42/mnm. The sample annealed at a longer period, that is, 24 h, shows a higher degree of crystallinity compared to the 12 h annealed sample. It also shows a smaller full width at half maximum (FWHM), indicating larger crystallite size for the 24 h annealed sample. The particle size analysis reveals that there are two groups of particle size distributions for both samples. SEM results give values that are different from the particle sizer results due to the different nature of the measurement methods.

Abstract: In the present work, the microstructure evolution of Mg-4Al-2.5Ca alloy during solidification was investigated by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and differential scanning calorimetry (DSC). The results showed that the as-cast microstructure was typical dendritic structure, consisting of α-Mg and the Al₂Ca with a C15 structure formed at inter-dendritic regions. But during slow solidification, the sequence of phase formation of this alloy consisted of following stages: L→ L + α-Mg → L + α-Mg + (Mg, Al)₂Ca → α-Mg + (Mg, Al)₂Ca + Al₂Ca → α-Mg + Al₂Ca. Thermal analysis showed that the (Mg, Al)₂Ca and Al₂Ca phase separation temperature was about 520°C and 510°C respectively, which is different from thermodynamic calculation. With the temperature decreasing, the liquid (Mg, Al)₂Ca phase with thick and continuous morphology transformed into lamellar-shaped eutectic phase, and parts of (Mg, Al)₂Ca phase translated into Al₂Ca phase with bone-shaped and needle-like.

Abstract: A testing circuit of probe is designed to research the electrical properties of the probe under different loading frequencies. Sinusoidal signals of different frequencies are produced by Tektronix AFG3102 signal generator, and DSOX2022A Oscilloscope is used to measure the probe voltage,constant resistance voltage and the source voltage, so the phase between the probe voltage and constant resistance voltage can be calculated. Assumed the constant resistance is a pure resistance. Since the circuit is connected in series, so the phase between the probe voltage and the probe current can be calculated. The result reveals that the probe shows resistive when the phase between the probe voltage and the probe current is 0 ° within 200 KHz frequency. Beyond 200 KHz the phase between the probe voltage and the probe current increases to 60 ° and then declines to a steady value 40°, which shows that the probe is inductive.

Abstract: In order to investigate the disposal of plutonium by Gd₂Zr₂O₇, Ce-doped Gd₂Zr₂O₇ were fabricated by high temperature solid state reaction at 1500 °C under atmospheric pressure for 72 h. XRD and SEM studies were exploited to characterize the crystal structure and microstructure of the synthetic samples. The results revealed that Gd₂Zr₂O₇ shows a single pyrochlore structure while Gd₂Ce₂O₇ exhibit a defective fluorite structure. The microstructure of the samples was relatively dense, and the grain size was in the range of 3 - 6 μm.

Abstract: The method of translucent diffraction electronic microscopy conducted researches of a microstructure and phase structure of a titanic alloy of VT1-0 implanted by ions of aluminum. There are two types of grains; 1) large grains (LG) with an average size of 1.4 microns and 2) the small grains (FG) with an average size of 0.5 μm. It is established that as a result of radiation the ion-alloyed layer, on the basis of α-Ti grains is formed. The sizes, form and places of localization of secondary phases (Ti₃Al, Al₃Ti and TiO₂) depend on the size of grain of a titanic matrix. The size of dispersive hardening of σ_or for different type of grains on depth of the ion-alloyed layer is calculated. It is shown that in MZ the size σ_or is provided only with TiO₂ particles, in LG – generally TiO₂ particles.

Abstract: The influence of chromium cast iron Cr8 treatment by Fe-45Si-6Mg-0,5REM modifier on the structure, phase transformation and heat resistance was studied experimentally.It is demonstrated that during modifying of chromium cast iron Cr8 the alloying effect takes place. The initial cast iron structure which consists of alloyed ferrite, carbide (Cr,Fe)₇C₃ and cementite (Fe,Cr)₃C is transformed as in the process of chromium alloying according to modifier consumption increase. At the modifier consumption of 0,15 % the mass quota of cementite (Fe,Cr)₃C decreases from 3,2 % to zero, and the mass quota of carbide (Cr,Fe)₇C₃ increases from 20 % up to 30 %.

Abstract: Anthracite and bitumite were processed respectively at 1400°C,1700°C, 2000°C, 2200°C, 2400°C and 2600°C,and their chemical composition,resistivity,microstructure, phase composition,and the internal migration of molecular functional group were tested and characterized. The results indicate that moisture, ash and volatile in coal have gradually shifted and lost with the elevation of heat treatment temperature, while the higher temperature, the quicker and completer phase change. Heat treatment can make the coal transform from approximately insulative phase to conductive phase,. Furthermore, as the temperature increases, the conductive phase transformation effect is better. The higher the heat treatment temperature of coal, the more amorphous carbon transforming into crystalline carbon completely, but the less types of phases .

Abstract: Features analysis of propagation for harmonic probing signal having spiral topology of ax symmetric conducting inductive structure is conducted. The structure has violations in the form of short circuit of adjacent coil’s turns. Visualization of the results obtained is represented involving Parawey fan to spatially display phase distortions during the propagation of probing harmonic signal having ax symmetric vortex structure with violation in the form of the short circuit of coil topology.

Abstract: In order to investigate the fabrication of pyrochlore Gd₂Zr₂O₇, Gd₂O₃ and ZrO₂ were used as raw materials in the process. Pyrochlore Gd₂Zr₂O₇ were fabricated by high temperature solid state reaction at 1100 – 1600 °C under atmospheric pressure for 72 h. XRD and SEM studies were exploited to characterize the crystal structure and microstructure of the synthetic samples. The results revealed that Gd₂Zr₂O₇ with a single pyrochlore structure was fabricated successfully at 1500 °C. The microstructure of the sample was uniform and dense, and the grain size was in the range of 1 - 3 μm.

Abstract: Every person is surrounded by different things with various time of consumption. The most of people sees a product life cycle from a marketing point of view. The product has got to prosper on the market place and to earn money for the organisation and to be cheap for the customer. However, the market has changed dramatically. Organisations have not adapted on these conditions yet. The article tries to assess different views on the product life cycle according to publications. The need of an adjustment of the product life cycle is described here with regard to the process approach in management systems of organisations. Another resource of knowledge for products is based on years of observation of the nature. There are also discussed general requirements for the product from a common domestic customer. The goal of this article is to contribute to a new approach to the product life cycle, which includes all these aspects. Products have to get closer to the concept of the sustainable living as a way overcoming of the crisis. They can not be conceived only grossly economically.