In this study, Orihi (Apa-Benue, Nigeria) clay, Jatropha curcas and Nigella sativa seed oils were evaluated as binders for production of foundry silica sand cores. The results of the physiochemical tests on the clay and oils indicated that Orihi clay contains up to 67.50 % SiO2, while high iodine content, saponification value, and free fatty acid on the oils suggest their good potential as binder materials for production of foundry cores. Various core test samples were produced and baked at 180 oC for 30 - 150 minutes. The results of both shatter index, and permeability tests indicate better binding characteristics combining clay with the oils. The results of strength tests also indicate that, while a maximum backing compressive strength of 234 kN/m2 could be achieved using clay as binder, up to 842 kN/m2 was obtained using the oil mixtures at a baking time of 2.5 hours, and combining clay and the oils gave up to 3010 kN/m2 . Based on these results, it was concluded that Orihi clay, Jatropha curcas and Nigella sativa seed oils are suitable for use as binders for the production of silica sand cores in foundries.

The application on non-cementious concrete are widely discovered for industry as to enhance the use of waste material, fly ash. Fly ash known as geopolymer binder which can improve the mechanical performance of the concrete and reinforcement impart strength to the concrete, relatively. Reinforcement correlate improvement in the blast resistance when retrofitted with the steel bar and fibres. The levels of damage after the blast explosion rely on the types of reinforcement in the concrete matrix. Meanwhile, the mass of explosive and distance of explosive to the concrete beam used in experiment field also affect the level of damage after blasting. The 3 beams was tested in the field blast experiment by using different scaled distance that are 0.298 m/kg1/3 , 0.224 m/kg1/3 and 0.149 m/kg1/3. Impulsive impact from the explosive detonation with the lowest scaled distance bring the most effect against the concrete. This paper represent the geopolymer concrete beam with steel bar reinforcement response towards explosive air blast loading.

The hardness, microstructure and wear behavior of EN 1.2379 cold work tool steel were investigated in different heat treatment condition. In metal forming industry tools can be exposed to very complex and surface demanding conditions, which are the result of different mechanical, thermal, chemical or tribological effects and require well defined properties. The aim of present work was to investigate the properties after conventional treatment, plasma nitriding and cryogenic treatment. The results show that it is an effective way to improve the properties of the tool steels modifying the microstructures and the surface through heat and chemical treatments. Using different heat treatment processes and parameters, the microstructure of a tool steel can be modified and optimized for a selected application.

The effects of cut thickness and cutting speed on cutting forces in an orthogonal turning process have been studied using a CNC lathe for 3 different cutting speeds (100, 150 and 200 m/min) at a constant cut thickness of 0.17 mm and 4 different cut thicknesses (0.1, 0.17, 0.24 and 0.31 mm) at a constant cutting speed of 200m/min. Four tool wearlands (0, 0.2, 0.4 and 0.6 mm) were used for both combination of cutting parameters. The forces were measured using a piezoelectric dynamometer. The analysis of variance (ANOVA) was performed and result shows that cut thickness significantly affects cutting forces while cutting speed does not at 95% confidence. At a wearland of VB=0 mm and cutting speed of 200 m/min, the measured power force (Fcm) increased as cut thickness increases with the least measured value observed as 802.9 N while at a wearland of VB=0 mm and cut thickness of 0.1 mm, the measured thrust forces (Ftm) increases as the cutting thickness is increased with a least observed value of 500.9 N. These form a basis for selecting optimal cutting conditions to machine the mild carbon steel.

The influence of three varieties of surfactants on intermolecular interactions in the bulk phase of a film-forming polyphenylsiloxane was studied by viscosimetric and dielectrometric methods. A linear increase of specific viscosity with increase of polyphenylsiloxane concentration at constant temperature was observed. In solutions of all studied amine derivatives at concentrations above 0.5 g/dm3 , a significant deviation from the linear dependence of the specific viscosity with surfactant concentration was found. The results indicated the formation of associated structures. The viscosity incremental growth in the concentration range of 0.5-2 g/dm3 corresponded to the molecule-weight ratio of amino derivatives. Rheological properties of solutions of the studied amino derivatives was slightly effected by the temperature. The specific viscosity of solutions of low molecular weight amines increased at higher temperatures. The most pronounced change was noticed at concentration of surfactant of 0.5 g/dm3 . The effect was supposed to be due to solvation processes. In contrast, the specific viscosity of the solutions of high molecular weight amine derivatives decreased with increase of temperature up to T = 313 K. It was supposed that the temperature increase caused an increase in intermolecular interactions within the associates, which was accompanied by a decrease of their dimensions. The formed intermolecular structures folded into a tight ball creating less resistance for a flow and as a result the specific viscosity decreased. At increased surfactant concentrations (CSURF> 0.25 g/dm3 ), two types of association processes (mono and hetero-) were established depending on the individual characteristics of the organic amino derivatives (composition, structure, shape and hydrocarbon radical length). It has been proved that, the interaction between each other (monoassociation) was energetically more favorable for high-molecular amines with the simultaneous introduction of polyphenylsiloxane solutions macromolecules (mixed miccels) into their composition. In the solutions containing low-molecular amines, monoassociation processes were proved.

This contribution presents thermal load stress analysis of insulating glass units (IGU) integrated in Trombe walls. It is based on modelling and numerical simulation of the heat transfer processes occuring in the construction. The boundary conditions are based on experimental data, obtained from an existing Trombe wall test module, situated at the Technical University of Sofia. The investigations are performed for different cases of IGU fixing in the Trombe wall. The temperature fields and the ensuing thermal stresses in the IGU at winter conditions, obtained from the simulations, are used to analyze the possibility of glass failure due to the internal pressure loads.