Defect and Diffusion Forum Vols. 326-328

Abstract: Three samples of 10GN2MFA steel were thermally treated at quenching temperatures equal to 900°C, 1000°C and 1100°C, and temperature of the tempering was 670°C. Thermo-physical properties of the steel were modelled by lumped capacity model. The sample was mechanically stressed under yield strength and then the cooling curve of stressed material on air was measured. The heat transfer through grips was taken into account. Thermo-physical properties were obtained by parametric fitting of time-temperature data obtained from cooling curve. Both thermal diffusivity and thermal conductivity increase with the quenching temperature. Specific heat capacity of steel samples after thermal treatment does not change significantly. All the measured thermo-physical parameters were in good agreement with the table values for low carbon Ni steels.

Abstract: The contribution deals with the use of artificial neural networks for prediction of corrosion loss of structural carbon steel. Nowadays there is certain chance to predict a corrosion loss of materials by artificial intelligence methods, especially by neural networks. A model of neural network for prediction of corrosion loss of structural carbon steel based on the input environmental parameters affecting the corrosion of metals in the atmospheric environment (temperature, relative humidity, air pollution by sulphur dioxide and the exposition time) was created. The model enables to predict corrosion loss of steel with a sufficiently small error.

Abstract: The paper is devoted to the study of thermal, as well as mechanical properties of polyurethane samples (PU) filled by carbon black (CB), graphite (G) and MWCNT(CNT). Thermal conductivity k(W.m^-1.K^-1), specific heat capacity c_p(J.kg^-1.K^-1) and thermal diffusivity a(mm².s^-1) were measured by the impulse method. An increase of all the above mentioned thermal parameters after addition of fillers under investigation was observed. The dc electrical conductivity drastically increases from PUPU+CBPU+GPU+CNT.

Abstract: The solidification of binary Al-Sc melts containing small amounts of scandium (< 2 wt.%) have been investigated. We studied concentration profiles in long Al-Sc as cast ingots formed by slow cooling of the liquid alloys. It was found that minor addition of transition metals like Ti can lead to the formation of large (about 10-20 μm) spherical intermetallic particles (Al₃Sc containing some amount of isomorphic Ti). These sphere-like particles are forming during the crystallization of liquid solution of Sc in Al (before the precipitation on nanosize spherical particles from the solid solutions). The results of SEM and EDX investigations of these alloys are also presented in this paper.

Abstract: The objective of the research is to represent a novel arrangement of conical three dimensional rough tubes (FS3D) for heat transfer coefficient enhancement. Experiments were performed with 316 stainless steel tubes of FS3D roughness and hot crude oil was circulated in constant heat flux condition in the related set up. The pressure drop is measured in this set up and compared with the pressure drop in a smooth tube with the same operating conditions. The heat transfer coefficient is one of essential parameters for design of heat transfer equipments and in this experimental work this is investigated for an Iranian crude oil in the FS3D rough tube. The heat transfer coefficient in FS3D rough tubes is higher than in other commercial enhanced tubes. FS3D rough tubes improve the performance of heat transfer equipments and also optimize the size of the mentioned devices. Consequently this type, the FS3D rough tube, is advantageous in energy and cost saving.

Abstract: C₆₀ coated Si thin films were prepared sequentially by a plasma enhanced chemical vapor deposition and a plasma assisted thermal evaporation technique. The films were then utilized as anode materials for lithium ion batteries. The diffusion coefficients of Li-ions in the film electrodes were then estimated by typical electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. The diffusion coefficients determined by both methods were found to be consistent each other. The diffusion coefficient of coated samples was obviously higher than that of bare silicon thin films, indicated that the kinetic properties of lithium ion transport in silicon film electrodes were enhanced by the C₆₀ film coating on its surface.

Abstract: Immobilized enzymes enhance process robustness, allow longer duration of activity of enzymes, and re-use of the same enzymes in multiple cycles. Enzymes can be operated in the liquid form or immobilized on various supports. In this work, we prepared gold nanoparticle core-shell structure by assembling of the gold nanoparticles on the surface of amine-functionalized x-type zeolite and then used them for immobilization of the alkaline protease. Characterization of these assembled systems were carried out by UVvisible, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX). Biocatalytic activity of the alkaline protease in this bioconjugate system was examined and showed an increase in comparing with the free enzyme in solution.

Abstract: The diffusion of guest molecules in zeolites is investigated in the framework of a onedimensionallattice-gas model with two non-equivalent sites. The concentration dependenciesof the tracer and center-of-mass diffusion coefficients are calculated for some representative valuesof the lateral interaction between the guest molecules. Using simple ideas about moleculesdiffusion we propose analytical expressions for the diffusion coefficients. We compare the theoreticaldependencies with the numerical data obtained by the kinetic Monte Carlo simulations.A very good coincidence of the data obtained by the two quite independent different methodscorroborates strongly the validity of the proposed approach.

Abstract: ndia is veritable emporium of medicinal and aromatic trees. It has been estimated those trees occurring in India are commonly useful. Neera natural liquid is useful for different purpose like in bio-medical, chemical industries etc. The study of elastic behaviour of a solid is very important in fundamental and technical research. Solid bodies are not absolutely rigid by the application of suitable forces. We used the composite piezoelectric oscillator technique to calculate elastic behaviour of Borassus Flabellifier wood part from where the natural liquid NEERA collected overnight. Non-destructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. Ultrasonic Inspection is a very useful and versatile NDT method to calculate the ultrasonic longitudinal velocity and elastic constant of male and female tree (Borassus Flabellifier) wood part in the longitudinal and perpendicular direction of fibres with frequency at room temperature of 311 K. We have measured the resonant frequencies of the specimens f_s. The specimens were collected from Dhar Dist. (M.P.) India. Characterization of the samples was made by scanning electron microscope (SEM) Model JEOL JSM5400. The resonant frequencies of the specimens were measured by Ultrasonic Interferometer (for solids) dual frequency Mittal Enterprises, New Delhi.

Abstract: Due to the depletion of high-quality iron ore, it is becoming ever more urgent to involve the ores which, for some reason or other, could not be used in metallurgy, or were used in limited quantities. For example, the siderite ores of Bakalsk deposit (Chelyabinsk region, Russia, stocks of more than 1 billion tons) are of very limited use in the blast-furnace practice because of the relatively low iron content (29% on average) and high magnesium oxide content (11-15%). At present, the technology of obtaining calcined siderite concentrate (CSC) from the ores of Bakalsk deposit includes raw ore roasting (fractions 10 - 60 mm) in blast furnaces at temperatures above 1000⁰С, and dry magnetic separation.