Defect and Diffusion Forum Vol. 365

Abstract: A Pd-H system is a model system suitable for studying interactions of hydrogen with metals. In the present work, we studied hydrogen-induced buckling of thin Pd films deposited on various substrates with different bonding strengths (sapphire, glimmer) and also the effect of deposition temperature. Lattice expansion and phase transitions were investigated by X-ray diffraction of synchrotron radiation. The influence of the substrate and microstructure of the film on the buckling process and phase transformation to palladium hydride are discussed.

Abstract: Observing the latest manufacturing processes, the following tendencies can be noted: the gain of the energetic efficiency and shortening of the processing time with parallel preservation of the dimensions tolerance, shape tolerance and outer layer quality of the processed workpiece. Also the possibilities of gaining efficiency by rising criteria for process parameters are limited. It is mainly observed in the processing of hard machinable materials like titanium alloys or sintered carbides. Problems related to poor machinability were revealed during the final manufacturing processes using abrasive grinding [1,2]. In this work the results which have been presented are related to the influence by selected electrical parameters of the Abrasive Electrodischarge Grinding (AEDG) on the surface layer temperature of machined samples, in comparison to conventional grinding. Also the change in temperature during the AEDG has been depicted. The basis of this work is similar to the investigations of the deep grinding of surfaces of the titanium alloy Ti6Al4V using CBN and a diamond grinding wheel. For the comparative evaluation of the conventional grinding and AEDG, measurements of the specific grinding energy, energy of the spark discharge and internal stresses in the surface layer have been used.

Abstract: Liquefied natural gas (LNG) has the cryogenic temperature of –160°C to ensure the minimum storage volume when stored in LNG containers. Among various types of LNG storage containers, the full containment above-ground type with a double safety system (outer concrete tank and inner steel tank) is very common. Normally, the inner tank contains LNG, but when the LNG leaks from the inner tank, the outer concrete tank comes into contact with LNG. Under this accidental case, it is indispensable for the outer wall to keep the liquid tightness in order to safely contain the LNG before taking any countermeasure. It is, therefore, proposed to take up a heat conduction problem using the finite element method with the ANSYS software to obtain temperature distribution data of a concrete wall at cryogenic temperatures.

Abstract: This paper aims to present an experimental study of rough rice (BRSMG CONAI cultivar) drying by using a stationary method. The grain was dried in an oven with air mechanical movement under controlled conditions of velocity, temperature and relative humidity. In order to obtain balanced moisture content, the samples studied were kept at 40 and 70°C. Results of the drying and heating kinetics of the grain during the process are shown and analyzed. It was found that higher drying rate and lower time for drying as higher air temperature (70°C) is used. It can be concluded that the reduction of the moisture content of the grain, is considered very complex and, depending on the method and drying conditions, can substantially provokes breaking and cracks, which reduces final product quality.

Abstract: This work aims to study convective drying of ellipsoidal solids. Aplication has been done to drying of wheat Kernel. Diffusion equation in cylindrical coordinates has been solved via Galerkin-based integral method considering convective boundary conditions and constant thermo-physical properties. Results of the temperature and moisture content are presented and compared with wheat experimental drying data at relative humidity 33.8 % and temperature 47.0°C. It was verified that heat transfer in the drying process occurs much faster than the mass transfer, thus providing a rapid heating of the product, which reduces grain quality.

Abstract: This work aims to investigate the infiltration of a CaCO₃ filled resin in fibrous porous media (resin transfer molding process) using the PAM-RTM software. A preform of glass fiber mat (fraction 30%), with dimensions 320 x 150 x 3.6 mm, has been used in rectilinear injection experiments conducted at room temperature and injection pressure 0.25, 0.50 and 0.75 bar. The polyester resin contain 0% and 40% CaCO₃. The numerical results were evaluated by direct comparison with experimental data. The flat flow-front profile of the rectilinear flow was reached approximately half length of the mold. It was observed, that the both velocity infiltration and permeability have decreased with increasing the CaCO₃ content, thus, increasing the time to processing of the composite material.

Abstract: The aim of this research is to study the pollutant emissions of the commercial diesel engine, operating with B5 (commercial diesel), B70, B80, B90 and natural gas. The fuel used in the engine consists of a mixture of 15% diesel and biodiesel (liquid fuel) and 85% natural gas. Experiments were made using 40, 60 and 80 kW load. The engine was instrumented to obtain the temperature, air, gas and diesel (plus biodiesel) flow rates, the air pressure at the entrance of the engine, the lubricant oil temperature, and the concentration of exhaust gases during each experimental test. It was verified that the emission of NO_x, NO and CO₂ had decreased while the emissions of CO and SO₂ had increased, when compared to the conditions using standard diesel (B5) alone.

Abstract: This work presents an experimental study on the behavior of clays during the drying process. Experimental tests were carried out with clay material for the production of red ceramics and white ceramic (ball clay). Different dimensions and the material initial moisture content plus temperature and relative air-drying humidity were taken into account. Drying kinetics and volume changes of parallelepiped-shaped samples were shown and analyzed. It has been verified that air-drying temperatures and body shape have an enormous influence on the drying rate process. The drying process occurs during the falling drying period and the volume changes display two linear periods.

Abstract: This paper aims to highlight the study of polymeric composite responsible development with the environment and with the growth of the recycling of materials, from the use of high density polyethylene (HDPE) with eucalyptus wood dust from the furniture manufacturing. The study started from a literature search where they were analyzed the factors involving the subject in question, highlighting the concept of polymer, synthetic fibers, wood powder presence, composites to identify and understand the problem in issue. The study was developed from mechanical, morphological and rheological testing of composites with concentrations of 0, 5, 10 and 20% wood in relation to the polymer matrix in order to characterize and compare the obtained materials. Based on this context, this study was developed based on material supplied by a sawmill, where we used wood dust to perform the necessary tests and experiments, thus aiming to analyze the possibility front the production of HDPE composite from the use of different fractions.

Abstract: The aim of this research is to investigate the influence of solidification thermal parameters on the macrostructure of an Al-7wt%Si alloy during the horizontal directional solidification under unsteady-state heat flow conditions and its correlation with cutting temperatures. The solidification experiments were instrumented by thermocouples and an experimental approach was developed to quantitatively determine the solidification thermal parameters considered. The observation of the macrostructures has indicated that the columnar-to-equiaxed transition occurred in a sharp plane parallel to the chill wall and a higher average cutting temperature was obtained for the columnar structure.