Synthesis and characterization of Cu-ZrB2 alloy produced by PM techniques

The copper alloy with 7vol.% ZrB2 examined in this study was consolidated via powder metallurgy processing (PM) by combining mechanical alloying and hot pressing process. Structural changes, morphological properties and elemental analysis of the hotpressed samples were studied as a function of milling time with the use of X-ray diffraction, scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry (EDS). Also, mechanical properties of the Cu-7vol.%ZrB2 alloy was investigated. Distribution of ZrB2 particles and presence of agglomerates in the Cu matrix directly depend on the milling time and show strong influence on hardness, compressive and electrical properties of Cu-ZrB2 alloys. [Projekat Ministarstva nauke Republike Srbije, br. 172005

Wetting phenomena of grooves at liquid metal/ceramics interface

The grain boundary groove (GBG) developing at the ceramic substrate under the liquid metal is evident, yet not fully explained influencing appearance in describing the wetting phenomena at liquid metal/ceramics interface. The focus here is on modeling of the phenomena at/around a groove between grains depending on grooves’ geometry. Based on atomic force microscopy results, the groove efficiency assessment is provided as a function of the transferred mass quantity and related to grooves geometry. The transferred mass quantity and, according to it, the groove efficiency at parabolic GBG is about 10 % higher comparing to the triangular GBG

A numerical analysis as a good tool for a prediction of final sulphur steel ladle content

This work presents the industrial results of sulfur level prediction at the end of vacuum degassing (VD) of low carbon Al-Si killed steels. The effect of plant conditions, such as slag chemistry, temperature, oxygen levels of the molten steel, and slag weight on desulphurization was investigated based on the measured results and thermodynamic calculations. The variables which influence steel desulfurization such as the sulfur capacity, the initial sulfur content, and the amount of ladle slag at the end of the VD process are also defined. The desulfurization procedure was numerically analyzed using the results of 31 heats under real plant conditions in which the measured final sulfur content had been reduced to less than of 10 ppm. A method for prediction of the slag amount based on the material balance of sulfur and aluminum is also presented. The values of the sulfur capacity were determined according to the well-known KTH and optical basicity based models. The obtained results of the regression equation show a predictive final sulfur level ability of R=0.911. This was proved as satisfactory

A numerical analysis as a good tool for a prediction of final sulphur steel ladle content

This work presents the industrial results of sulfur level prediction at the end of vacuum degassing (VD) of low carbon Al-Si killed steels. The effect of plant conditions, such as slag chemistry, temperature, oxygen levels of the molten steel, and slag weight on desulphurization was investigated based on the measured results and thermodynamic calculations. The variables which influence steel desulfurization such as the sulfur capacity, the initial sulfur content, and the amount of ladle slag at the end of the VD process are also defined. The desulfurization procedure was numerically analyzed using the results of 31 heats under real plant conditions in which the measured final sulfur content had been reduced to less than of 10 ppm. A method for prediction of the slag amount based on the material balance of sulfur and aluminum is also presented. The values of the sulfur capacity were determined according to the well-known KTH and optical basicity based models. The obtained results of the regression equation show a predictive final sulfur level ability of R=0.911. This was proved as satisfactory

Relationship between the common optical basicity models and the sulphide capacities of CaO-Al 2O 3-SiO 2-MgO slag

The correlations between the sulphide capacity and the optical basicity models available in literature are reviewed. The relationship between sulphide capacity and the optical basicity was investigated on plant data collected from the BOF plant in the temperature range of 1565- 1650°C. The goal of this work was to compare results given by applying common acceptable Young's, Sosinsky-Sommerville's, Tsao-Katayama's and Taniguchi's optical basicity as well as the KTH model for calculating the sulphide capacities. The present paper is focused on the thermodynamic aspect of sulphur refining CaO-Al 22 3-SiO 2-MgO ladle slag during LF ladle treatment. Thirty one heats were employed in the present study in real production conditions of low carbon steels

Prednosti uspostavljanja i kontrola režima livenja na primeru odlivka klipa

S. Manasijević, R. Radiša, Z. Pavlović-Aćimović,K. Raić, Prednosti uspostavljanja i kontrola režima livenja na primeru odlivka klipa, LIVARSTV

Optimization technological parameters of piston casting using information technology

Optimization technological parameters of piston casting using information technology, 12th International Foundrymen Conference, Sustainable Development in Foundry Materials and Technologie

Persistent organochlorine compounds in human milk collected in Croatia over two decades

The distribution and time trend of organochlorine pesticide (OCP), polychlorinated biphenyl (PCB), and polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran (PCDD/PCDF) concentrations in human milk samples from Croatia collected in 1981-2003 are presented. Between 1981/1982 and 1987/1989, the concentrations of HCB, beta-HCH, DDE, and total PCBs decreased about 50%, while for the last decade, the concentrations have been decreasing very slowly. In 2002/2003 the range of PCB congeners and OCPs was from below the limit of determination to 332 ng g(-1) milk fat. PCDD/PCDF concentrations in human milk samples collected in 1981-2000 ranged between 5.2 and 26.7 pg I-TEQ g(-1) milk fat and showed a decreasing trend

Synthesis and sintering of Cu-Al2O3 nanocomposite powders produced by a thermochemical route

By hydrometallurgy and powder metallurgy along with prognosis of physical-chemical properties, a synthesis of new improved materials can be successfully performed with in advance pre-set properties which is conditioned by a quality of starting powders i.e. by improving their structure. In accordance with that, this paper presents synthesis of the nanocomposite Cu-Al2O3 powder by thermochemical method and sintering with a comparative analysis of the mechanical and electrical properties of obtained solid samples. Nanocrystaline Cu-Al2O3 powders were produced by thermochemical method through following stages: spray-drying, oxidation of precursor powder, reduction by hydrogen and homogenisation. Characterization of powders included differential-thermal and thermo-gravimetric analysis (DTA-TGA), X-ray-diffraction (XRD) and analytical electron microscopy (AEM) coupled with energetic dispersive spectroscopy (EDS). Size of produced powders was 20-50nm with noticeable presence of agglomerates. Composite powders are characterized with A12O3 homogenous distribution in copper matrix. Powders were cold pressed with pressure of 500 MPa and sintered. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperature range from 800 to 900°C and time up to 120 minutes. Characterization of Cu-Al2O3 sintered system included examination of density, relative volume change, electrical and mechanical properties, examination of microstructure by SEM analysis, as well as by EDS. The obtained nanocomposite, which structure is with certain changes preserved in final structure, has provided sintered material with homogenous distribution of dispersive in copper matrix, with exceptional effects of reinforcing and excellent combination of mechanical and electrical properties