marija korac | Univeristy of Belgrade, Faculty of Technology and Metallurgy (original) (raw)

Papers by marija korac

Research paper thumbnail of Nanocomposite powders for new contact materials based on copper and alumina

Chemical Industry & Chemical Engineering Quarterly, 2008

This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure design... more This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

Research paper thumbnail of Sintered materials based on copper and alumina powders synthesized by a novel method

Science of Sintering, 2010

This paper presents the production of sintered materials from nano-composite powders obtained by ... more This paper presents the production of sintered materials from nano-composite powders obtained by a novel synthesis method, which represents a combination of thermochemical synthesis and mechanical alloying. Produced powders were characterized by an average individual particle size of 30nm, with the presence of a small number of aggregates with a size of 150nm. The positive effect on dispersion strengthening of the copper matrix occurred up to 1 wt.% Al 2 O 3 , whereas a further increase of the Al 2 O 3 content showed a negative effect on hardness. The new synthesis method is more suiTab. for composite materials containing maximum 1wt.% Al 2 O 3 . By this novel method it is possible to produce composites possessing a good combination of hardness and electrical conductivity.

Research paper thumbnail of Sintering of Cu-Al2O3 nano-composite powders produced by a thermochemical route

Journal of The Serbian Chemical Society, 2007

This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method... more This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu-Al 2 O 3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA-TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20-50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al 2 O 3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu-Al 2 O 3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties.

Research paper thumbnail of Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

Science of Sintering, 2007

In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown ... more In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electricmechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al 2 O 3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al 2 O 3 . Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-raystructure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900 o C for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al 2 O 3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties.

Research paper thumbnail of Nanocomposite powders for new contact materials based on copper and alumina

Chemical Industry & Chemical Engineering Quarterly, 2008

This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure design... more This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

Research paper thumbnail of Sintered materials based on copper and alumina powders synthesized by a novel method

Science of Sintering, 2010

This paper presents the production of sintered materials from nano-composite powders obtained by ... more This paper presents the production of sintered materials from nano-composite powders obtained by a novel synthesis method, which represents a combination of thermochemical synthesis and mechanical alloying. Produced powders were characterized by an average individual particle size of 30nm, with the presence of a small number of aggregates with a size of 150nm. The positive effect on dispersion strengthening of the copper matrix occurred up to 1 wt.% Al 2 O 3 , whereas a further increase of the Al 2 O 3 content showed a negative effect on hardness. The new synthesis method is more suiTab. for composite materials containing maximum 1wt.% Al 2 O 3 . By this novel method it is possible to produce composites possessing a good combination of hardness and electrical conductivity.

Research paper thumbnail of Sintering of Cu-Al2O3 nano-composite powders produced by a thermochemical route

Journal of The Serbian Chemical Society, 2007

This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method... more This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu-Al 2 O 3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA-TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20-50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al 2 O 3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu-Al 2 O 3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties.

Research paper thumbnail of Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

Science of Sintering, 2007

In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown ... more In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electricmechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al 2 O 3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al 2 O 3 . Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-raystructure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900 o C for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al 2 O 3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties.

Research paper thumbnail of Nanocomposite powders for new contact materials based on copper and alumina

Chemical Industry & Chemical Engineering Quarterly, 2008

This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure design... more This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

Research paper thumbnail of Sintered materials based on copper and alumina powders synthesized by a novel method

Science of Sintering, 2010

This paper presents the production of sintered materials from nano-composite powders obtained by ... more This paper presents the production of sintered materials from nano-composite powders obtained by a novel synthesis method, which represents a combination of thermochemical synthesis and mechanical alloying. Produced powders were characterized by an average individual particle size of 30nm, with the presence of a small number of aggregates with a size of 150nm. The positive effect on dispersion strengthening of the copper matrix occurred up to 1 wt.% Al 2 O 3 , whereas a further increase of the Al 2 O 3 content showed a negative effect on hardness. The new synthesis method is more suiTab. for composite materials containing maximum 1wt.% Al 2 O 3 . By this novel method it is possible to produce composites possessing a good combination of hardness and electrical conductivity.

Research paper thumbnail of Sintering of Cu-Al2O3 nano-composite powders produced by a thermochemical route

Journal of The Serbian Chemical Society, 2007

This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method... more This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu-Al 2 O 3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA-TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20-50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al 2 O 3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu-Al 2 O 3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties.

Research paper thumbnail of Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

Science of Sintering, 2007

In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown ... more In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electricmechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al 2 O 3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al 2 O 3 . Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-raystructure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900 o C for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al 2 O 3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties.

Research paper thumbnail of Nanocomposite powders for new contact materials based on copper and alumina

Chemical Industry & Chemical Engineering Quarterly, 2008

This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure design... more This paper is a contribution to characterization of Cu-Al 2 O 3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

Research paper thumbnail of Sintered materials based on copper and alumina powders synthesized by a novel method

Science of Sintering, 2010

This paper presents the production of sintered materials from nano-composite powders obtained by ... more This paper presents the production of sintered materials from nano-composite powders obtained by a novel synthesis method, which represents a combination of thermochemical synthesis and mechanical alloying. Produced powders were characterized by an average individual particle size of 30nm, with the presence of a small number of aggregates with a size of 150nm. The positive effect on dispersion strengthening of the copper matrix occurred up to 1 wt.% Al 2 O 3 , whereas a further increase of the Al 2 O 3 content showed a negative effect on hardness. The new synthesis method is more suiTab. for composite materials containing maximum 1wt.% Al 2 O 3 . By this novel method it is possible to produce composites possessing a good combination of hardness and electrical conductivity.

Research paper thumbnail of Sintering of Cu-Al2O3 nano-composite powders produced by a thermochemical route

Journal of The Serbian Chemical Society, 2007

This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method... more This paper presents the synthesis of nano-composite Cu-Al 2 O 3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu-Al 2 O 3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA-TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20-50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al 2 O 3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu-Al 2 O 3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties.

Research paper thumbnail of Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

Science of Sintering, 2007

In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown ... more In this paper synthesis of a composite based on Cu-Al 2 O 3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electricmechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al 2 O 3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al 2 O 3 . Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-raystructure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900 o C for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al 2 O 3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties.