The object of investigation was the one-strand tundish with flow control device such as gas permeable barrier (GPB). The aim of this flow control device was to activate the motion of liquid steel in the tundish longitudinal axis region. Computer simulation of the liquid steel flow and argon behaviour in isothermal turbulent motion conditions was done using the Ansys-Fluent computer program. For the validation of the hydrodynamic patterns obtained from computer simulations, a isothermal tundish glass model was used. Tundish glass model enables the recording of the visualization of fluid medium motion through the particle image velocimetry (PIV) method. Based on computer simulations, the liquid steel flow path lines in the tundish with GPB was obtained. For explain the hydrodynamic phenomena occurring in the tundish working space, the Buoyancy number has been calculated.

Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants applied in different ways on the surfaces under friction. In this work, AISI 316 austenitic stainless steel was coated with MoS2, using chemical vapor deposition (CVD) at four different temperatures (400, 500, 600 and 700°C). Coatings properties were investigated using SEM, EDX, XRD and FTIR, Hardness Tester and Roughness tester. The results showed that with simultaneous evaporation of sulfur and molybdenum trioxide (MoO3) in the CVD chamber, a uniform coating layer containing MoS2 and MoO2 phases was formed. Increase in the substrate temperature resulted in the rise in the amount of MoS2 to MoO2 phases. The thickness, grain size and the hardness of the coating were 17-29 μm, 50-120 nm and 260-480 HV respectively. Friction tests carried out using pin-on-plate method under normal loads of 10 N under ambient conditions showed values of the friction coefficient 0.25-0.40.

In the present work, the performance of multilayer coated carbide tool was investigated considering the effect of cutting parameters during turning of 34CrMo4 Low alloy steel. It has high strength and creep strength, and good impact tenacity at low temperature. It can work at –110°C to 500°C. And EN 10083-1 34CrMo4 owns high static strength, impact tenacity, fatigue resistance, and hardenability; without overheating tendencies. The objective functions were selected in relation to the parameters of the cutting process: surface roughness criteria. The correlations between the cutting parameters and performance measures, like surface roughness, were established by multiple linear regression models. Highly significant parameters were determined by performing an Analysis of variance (ANOVA). During the experiments flank wear, cutting force and surface roughness value were measured throughout the tool life. The results have been compared with dry and wet-cooled turning. Analysis of variance factors of design and their interactions were studied for their significance. Finally, a model using multiple regression analysis between cutting speed, fee rate and depth of cut with the tool life was established.

In the present work, rapidly solidified Al-10Ni-XSc (X = 0, 1 and 2) alloys were fabricated by melt spinning under Ar atmosphere. The Effects of Sc on the microstructural and thermal properties and microhardness values were investigated by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and a Vickers microhardness tester. Experimental results revealed that the addition of 2 wt. % Sc to melt-spun Al-10Ni alloys changed their brittle nature and hindered formation of cracks. The addition of Sc to melt-spun Al-10Ni alloys also changed the morphology of Al3Ni intermetallics from an acicular/needle – like to a rounded particle-like structure and led to reduction in their size. Formation of the metastable Al9Ni2 phase was observed due to the higher constitutional undercooling caused by Sc addition. A considerable improvement in microhardness value (from 95. 9 to 230. 1 HV) was observed with the addition of Sc.

In this paper the chemo-rheological behavior of aqueous TiC suspension and physical properties of gelcasted green body were investigated. The monomer system used in this project was acrylamide (AM) and methylenebisacrylamide (MBAM). Polymerisation reaction was promoted by the addition of tetramethyl ethylenediamine as a catalyst and ammonium persulfate as a initiator. The effects of tetramethylammonium hydroxide (TMAH), polyethylenimine (PEI) and polyethylene glycol (PEG) dispersants on the premix solution containing TiC powder have been studied via observation of the zeta potential and rheological behavior. The optimal amount of TMAH was achieved 0.4 wt.% at pH 9. The chemorheological results showed that the gelation time decreased and viscosity increased with increasing the monomer content, solid loading, initiator amount and temperature. The highest flexural strength of gel casted green body was obtained with 50 vol% solid loading and 25 wt.% monomers content.

The article presents the results of studies on the rate of zinc evaporation in the atmosphere of helium and carbon monoxide (II) carried out with the thermogravimetric method. The estimated values of zinc streams were compared with the values determined based on theoretical relationships.

This study offers a new method to synthesize facilely willemite (Zn2SiO4) based phosphor at the temperature of 800 °C. The ZnO-SiO2 nanocomposite was calcined at different temperatures between 500 and 1000 °C. The structural, morphological and optical properties of the nanocomposite obtained at various calcination temperatures were studied using different techniques. The FT-IR, XRD and the UV-vis result confirmed the formation of willemite phase. The precursor was confirmed to be amorphous by XRD at room temperature, but upon calcination temperature at 500 °C, it was transformed into a crystalline structure. The crystallinity and the particle size of the nanocomposite increase as the calcination temperature were increased as revealed by XRD and TEM measurement. The sample exhibits a spherical morphology from 500 to 800 °C and dumbbell-like morphology above 800 °C as shown by the FESEM images. The absorption spectrum suffers intense in lower temperature and tends to shift to lower wavelength in the UV region as the calcination temperature increases. The band gap values were found to be increasing from 3.228-5.550 eV obtained between 500 to 1000 °C, and all the results confirm the formation of willemite phase at 800 °C.

Microwave sintering process was employed to agglomerate ferromanganese alloy powders. The effects of sintering temperature, holding time and particle size composition on the properties and microstructure of sintering products were investigated. The results was shown that increasing sintering temperature or holding time appropriately is beneficial to increase the compressive strength and volume density. SEM and EDAX analysis shows that the liquid phase formed below the melting point in the sintering process, which leads to densification. XRD patterns indicate that the main reaction during microwave sintering is the decarbonization and carburization of iron carbide phase. The experiment demonstrate that the optimum microwave sintering process condition is 1150°C, 10 min and 50% content of the powders with the size of –75 μm

In this study a two-step short wet etching was implemented for the black silicon formation. The proposed structure consists of two steps. The first step: wet acidic etched pits-like morphology with a quite new solution of lowering the texturization temperature and second step: wires structure obtained by a metal assisted etching (MAE). The temperature of the process was chosen due to surface development control and surface defects limitation during texturing process. This allowed to maintain better minority carrier lifetime compared to etching in ambient temperature. On the top of the acidic texture the wires were formed with optimized height of 350 nm. The effective reflectance of presented black silicon structure in the wavelength range of 300-1100 nm was equal to 3.65%.

Mechanical properties and residual stresses of friction stir welded and autogenous tungsten inert gas welded structural steel butt welds have been studied. Friction stir welding (FSW) of structural steel butt joints has been carried out by in-house prepared tungsten carbide tool with 20 mm/ min welding speed and 931 rpm tool rotation. Tungsten inert gas (TIG) welding of the butt joints was carried out with welding current, arc voltage and the welding speed of 140 amp, 12 V and 90 mm/min respectively. Residual stress measurement in the butt welds has been carried out in weld fusion zone and heat affected zone (HAZ) by using blind hole drilling method. The magnitude of longitudinal residual stress along the weld line of TIG welded joints were observed to be higher than friction stir welded joint. In both TIG and FSW joints, the nature of longitudinal stress in the base metal was observed to be compressive whereas in HAZ was observed to be tensile. It can be stated that butt welds produced with FSW process had residual stress much lower than the autogenous TIG welds.

This paper presents the results of experiments on metallization of plastic elements produced using 3D printing technology from the light-hardened resins. The obtained coatings were bimetallic (Cu/Ni). The first step of metallization was the electroless deposition of copper. The second one was electrodeposition of nickel on the previously prepared copper substrate. The parameters of 3D prints preparation and metallization processes were deeply investigated. The etching of plastics substrates and duration of electroless metallization of 3D prints by copper were analyzed. In the next step the influence of nickel electrodeposition time was investigated. The coating were analyzed by XRD method and morphology of surface was analyzed by scanning electron microscopy (SEM). The thickness of coatings was calculated based on mass differences and measured by using optical microscopy method. The optimal parameters for both processes were specified.

An ecoefficient, economical and sustainable valorization process for the synthesis of Co3O4 from waste lithium-ion battery (LIB) by leaching-solvent extract-scrubbing-precipitation stripping route has been developed. Through an optimization, the waste LIB cathode was leached using 2000 mole/m3 of H2SO4 and 5 Vol. % of the H2O2 at a pulp density of 100 kg/m3 under leaching time 60 minutes and temperature 75 °C. From the separated leach liquor, cobalt was purified by saponified Cyanex 272. From cobalt, loaded Cyanex 272 impurities were scrubbed and the CoC2O4·2H2O was recovered through precipitation stripping. Finally, the precipitate was calcined to synthesize Co3O4, which is a precursor for LIB cathode materials manufacturing. From TGA-DTA, followed by XRD analysis it was confirmed that at 200 °C the CoC2O4·2H2O can be converted to anhydrous CoC2O4 and at 350 °C the anhydrous can be converted to Co3O4 and at 1100 °C the Co3O4 can be converted to CoO. Through reported route waste LIB can back to LIB manufacturing process through a versatile and flexible industrial approach.

This paper deals with the possibilities of using physical modelling to study the degassing of metal melt during its treatment in the refining ladle. The method of inert gas blowing, so-called refining gas, presents the most common operational technology for the elimination of impurities from molten metal, e.g. for decreasing or removing the hydrogen content from liquid aluminium. This refining process presents the system of gas-liquid and its efficiency depends on the creation of fine bubbles with a high interphase surface, uniform distribution, long period of its effect in the melt, and mostly on the uniform arrangement of bubbles into the whole volume of the refining ladle. Physical modelling represents the basic method of modelling and it makes it possible to obtain information about the course of refining processes. On the basis of obtained results, it is possible to predict the behaviour of the real system during different changes in the process. The experimental part focuses on the evaluation of methodical laboratory experiments aimed at the proposal and testing of the developed methods of degassing during physical modelling. The results obtained on the basis of laboratory experiments realized on the specific physical model were discussed.

Stability of silver nanoparticles strongly influences the potential of their application. The literature shows wide possibilities of nanoparticles preparation, which has significantly impact on their properties. Therefore, the improvement of AgNPs preparation plays a key role in the case of their practical use. The pH values of the environment are one of the important factors, which directly influences stability of AgNPs. We present a comparing study of the silver nanoparticles prepared by „bottom-up“ methods over by chemical synthesis and biosynthesis using AgNO3 (0.29 mM) solution. For the biosynthesis of the silver nanoparticles, the green freshwater algae Parachlorella kessleri and Citrus limon extracts were used as reducing and stabilizing agents. Chemically synthesized AgNPs were performed using sodium citrate (0.5%) as a capping agent and 0.01% gelatine as a reducing agent. The formation and long term stability of those silver nanoparticles synthesized either biologically and chemically were clearly observed by solution colour changes and confirmed by UV-vis spectroscopy. The pH values of formed nanoparticle solutions were 3 and 5.8 for biosynthesized AgNPs using extract of Citrus limon and Parachlorella kessleri, respectively and 7.2 for chemically prepared AgNPs solution using citrate. The SEM as a surface imaging method was used for the characterization of nanoparticle shapes, size distribution and also for resolving different particle sizes. These micrographs confirmed the presence of dispersed and aggregated AgNPs with various shapes and sizes.

The principle of work of many metallurgical shaft furnaces is based on the flow of reaction gas through the descending packed bed composed of metallurgical materials. Hot gases flow up the shaft furnace through the column of materials, give their heat to the descending charge materials. At the same time due to their reducing nature they interact chemically, causing the reduction of oxides inside the charge. In real conditions, during the course of the process, the powder is generated, the source of which is the batch materials or it is introduced into the as part of the process procedure. The powder in the form of thin slurry is carried by the stream of flowing gas. Such multiphase flow might considerably affect the permeability of the charge due to the local holdup of powder. The holdup of solid phase in packed beds of metallurgical shaft furnaces leads to radial changes in bed porosity. Radial changes in bed porosity uneven gas flow along the radius of the reactor and negatively affect the course and efficiency of the process. The article describes the model studies on radial distribution of carbon powder holdup in the packed bed composed of metallurgical materials. The powder was divided into fractions – “static” and “dynamic”. Large diversity of carbon powder distribution was observed in the function of the radius of reactor in relation to the bed type, apparent velocity of gas carrying powder and the level of bed height.

The paper evaluates two approaches of numerical modelling of solidification of continuously cast steel billets by finite element method, namely by the numerical modelling under the Steady-State Thermal Conditions, and by the numerical modelling with the Traveling Boundary Conditions. In the paper, the 3D drawing of the geometry, the preparation of computational mesh, the definition of boundary conditions and also the definition of thermo-physical properties of materials in relation to the expected results are discussed. The effect of thermo-physical properties on the computation of central porosity in billet is also mentioned. In conclusion, the advantages and disadvantages of two described approaches are listed and the direction of the next research in the prediction of temperature field in continuously cast billets is also outlined.

In the paper, the technology of the production of the modified ceramic proppants used in the shale gas extracting process is described. The natural available materials and uncomplicated process to new ceramic proppants preparation were applied. The modification of the ceramic proppants based on the addition of the waste material as fly ash. The produced ceramic material in the form of granules characterized by high mechanical properties and low production costs. Moreover, the obtained good values of compressive strength and gas permeability for investigated proppants confirmed that this material has appropriate properties to be used in the hydraulic fracturing.

Fe-40wt% TiB2 nanocomposites were fabricated by mechanical activation and spark-plasma sintering of a powder mixture of iron boride (FeB) and titanium hydride (TiH2). The powder mixture of (FeB, TiH2) was prepared by high-energy ball milling in a planetary ball mill at 700 rpm for 3 h followed by spark-plasma sintering (SPS) at various conditions. Analysis of the change in relative sintered density and densification rate during sintering showed that a self-propagating high-temperature synthesis reaction occurs to form TiB2 from FeB and Ti. A sintered body with relative density higher than 98% was obtained after sintering at 1150°C for 5 and 15 min. The microstructural observation of sintered compacts with the use of FE-SEM and TEM revealed that ultrafine particulates with approximately 5 nm were evenly distributed in an Fe-matrix. A hardness value of 83 HRC was obtained, which is equivalent to that of conventional WC-20 Co systems.

Metallic fuel slugs containing rare-earth (RE) elements have high reactivity with quartz (SiO2) molds, and a reaction layer with a considerable thickness is formed at the surface of metallic fuel slugs. The surface characterization of metallic fuel slugs is essential for safety while operating a fast reactor at elevated temperature. Hence, it is necessary to evaluate the surface characteristics of the fuel slugs so that chemical interaction between fuel slug and cladding can be minimized in the reactor. When the Si element causes a eutectic reaction with the cladding, it deteriorates the metallic fuel slugs. Thus, it is necessary to examine the characteristics of the surface reaction layer to prevent the reaction of the metallic fuel slugs. In this study, we investigated the metallurgical characteristics of the surface reaction layer of fabricated U-10wt.%Zr-Xwt.%RE (X = 0, 5, 10) fuel slugs using injection casting. The results showed that the thickness of the surface reaction layer increased as the RE content of the metallic fuel slugs increased. The surface reaction layer of the metallic fuel slug was mainly formed by RE, Zr and the Si, which diffused in the quartz mold.

In this study, precisely controlled large scale gas atomization process was applied to produce spherical and uniform shaped high entropy alloy powder. The gas atomization process was carried out to fabricate CoCrFeNiMn alloy, which was studied for high ductility and mechanical properties at low temperatures. It was confirmed that the mass scale, single phase, equiatomic, and high purity spherical high entropy alloy powder was produced by gas atomization process. The powder was sintered by spark plasma sintering process with various sintering conditions, and mechanical properties were characterized. Through this research, we have developed a mass production process of high quality and spherical high entropy alloy powder, and it is expected to expand applications of this high entropy alloy into fields such as powder injection molding and 3D printing for complex shaped components.

Among the various thin film coating techniques, atomic layer deposition (ALD) has features of good controllability of the thickness, excellent step-coverage in 3-dimensional object even in the sub-nm thickness range at the relatively low deposition temperature. In this study, SnO2 thin films were grown by ALD in the variation of substrate temperatures from 150 to 250°C. Even such a low temperature may influence on the growth kinetics of the ALD reaction and thus the physical characteristics of thin films, such as crystallinity, film density and optical band gap, etc. We observed the decrease of the growth rate with increasing substrate temperature, at the same time, the density of the film was decreased with increasing temperature. Steric hindrance effect of the precursor molecule was attributed to the inverse relationship of the growth temperature and growth rate as well as the film density. Optical indirect band gap energy (~3.6 eV) of the ALD-grown amorphous SnO2 films grown at 150°C was similar with that of the literature value, while slightly lower band gap energy (~3.4 eV) was acquired at the films grown at higher temperature.

Lead-free ceramics of Na0.5K0.5Nb1-xSbxO3 (NKNS) and Na0.5K0.5Nb1-xSbxO3 + 0.5 mol%MnO2 (NKNS + 0.5 mol%MnO2) (0 < x < 0.06) ceramics were prepared by a conventional solid-state hot pressing method. The ceramics possess a single-phase perovskite structure with orthorhombic symmetry. Microstructural examination revealed that Mn doping of NKNS leads to improvement of densification. The cubic-tetragonal and tetragonal-orthorhombic phase transitions of NKNS shifted to higher and lower temperature, respectively after introduction of Mn ion. Besides, ferroelectric and piezoelectric properties were improved. The results were discussed in term of difference in both ionic size and electronegativity of Nb5+ and Sb5+ and improvement of densification after Mn ion doping.

This article describes the influence of thermal and dielectric properties of materials to properties of electrical insulating systems in high voltage electrical equipment. The aim of this experiment is to improve the thermal and dielectric properties of electrical insulating (composite) materials using micro fillers of aluminium oxide Al2O3. Supplement of fillers of aluminium oxide with better thermal conductivity to the electrical insulating systems can be modified to increase their thermal conductivity. Improving the thermal conductivity of electric insulation by addition of micro- or nanofillers and in the same time not adversely affecting the dielectric properties is the objective of the study. Paper is presenting the results measured on prepared samples. Improved thermal conductivity is compared with other dielectric properties as: dissipation factor temperature dependences, resistivity and dielectric spectroscopy. To determine the dielectric insulating properties the following characteristics were measured: tanδ versus temperature from 110°C to 150°C, absorption and resorption currents, volume resistivity. Furthermore, this article describes analysis of moisture and conductivity the material by dielectric spectroscopy.

A series of Al-5Ti-1B master alloys were obtained via fluoride salt process by holding them between 780°C and 880°C for 10-90 min. The influence of holding temperature and time during preparation on the microstructure and its refining performance were investigated by X-ray diffractometer, optical microscopy and scanning electron microscopy equ ipped with energy dispersive X-ray spectroscopy. The results indicated both the morphology and the distribution of TiB2 and Al3Ti were seriously affected by holding conditions. Inadequate TiB2 particles were generated when holding time was short. However, Fe-containing impurity particles that aggregated along the matrix grain boundaries were found after the prolonged holding time. The refining and microhardness test results revealed that Al -5Ti-1B, the one held at 820°C for 30 min showed the optimum refining efficiency on Al-Cu alloy.