Vesna Maksimovic - Academia.edu (original) (raw)

Papers by Vesna Maksimovic

Modern industrial requirements include not only the usage of constructive materials with good mec... more Modern industrial requirements include not only the usage of constructive materials with good mechanical properties but also materials obtained through environmentally friendly and low-cost processing procedures. Basalt, as a low-cost raw material, is regarded as a good candidate for industrial constructive parts production. In the present study, andesite basalt originated from the deposit site "Donje Jarinje", Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing, and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070, and 1080 °C, and afterward the sintering duration was varied from 30 to 240 min at the optimal sintering temperature of 1060 °C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardn...

Numerous mechanical structures and assemblies have frequent outages because of wear of machine pa... more Numerous mechanical structures and assemblies have frequent outages because of wear of machine parts due to the effects of abrasion and erosion. There are several methods to protect parts from wear and one of them is by applying a protective coating on the endangered area. It is well known that the coatings with carbide distributed in a metallic matrix have an excellent wear resistance. In this paper characterization of three coatings were carried out: coating with tungsten carbide (WC) in NiBSiFe matrix, coating with chromium carbides (CrC) in FeNiSi matrix deposited by plasma transferred arc method (PTA), as well as, coating with WC carbide in CrNiBSi matrix deposited by oxy-acetylene thermal spray process. The above mentioned alloys, before application to the base material, were in a powder state. This paper describes applied coating technologies on a substrate -S235JR steel, powders characteristics, microstructure and properties of coatings, phase composition, and micro hardness of different microconstituents.

Ceramics International, 2014

ABSTRACT Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid... more ABSTRACT Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid as an inexpensive additive at low forming pressure and low sintering temperature. Starting raw material, smectite clay from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid was used as binding and sintering aid in amount of 0.5, 1 and 2 wt%. Powder was compacted by using different pressures: 40, 60 and 80 MPa. Pressed samples were sintered at 850, 1000, 1150, and 1300 degrees C for 4 h in air. A relatively high porosity of nearly 40% is obtained for the samples pressed at 40, 60 and 80 MPa and sintered at 1000 degrees C. Median pore size diameters are in the range of macroporous up to 0.2 mu m and 10 mu m in the samples sintered at 1150 and 1300 degrees C, respectively. X-ray diffraction (XRD), scaning electron microscopy (SEM), and porosimetry measurements were employed to characterize the phases and microstructure of the obtained ceramics. The relations between mechanical characteristics of samples (Young modulus and Poisson ratio) and content of boric acid were studied.

Journal of the Serbian Chemical Society, 2016

The effect of multiple recasting of commercial Co-Cr base dental alloy (Dentalit-C) on its struct... more The effect of multiple recasting of commercial Co-Cr base dental alloy (Dentalit-C) on its structural characteristics and ion release rates in artificial saliva has been investigated. The number of recasting was once, four and eight times. The as-cast microstructure became more uniform as the number of recasting was increased whereby macro and microhardness and electrical conductivity of the castings decreased. Metallic ion release in artificial saliva was monitored in vitro over the period of 22 weeks at the temperature of 37 0C and pH 2.3. Only Co and Fe were evidenced in artificial saliva and their release rates are measured. The ion release rates increases with time. The ion release rate of Fe was larger than Co. The ion release rates increases substantially by increasing the number of recasting.

Novel three-dimensional cobalt powder structures were successfully prepared by electrodeposition.... more Novel three-dimensional cobalt powder structures were successfully prepared by electrodeposition. Electrodeposited cobalt powder was characterized by scanning electron microscopy (SEM) and light microscopy. It was possible to control the morphology and structure of cobalt particles by adjusting process parameters of electrodeposition such as current density and type of working electrode. The morphology and structure of cobalt powders were investigated and the formation mechanism of agglomerate was also discussed.

Chemical Industry

One of the important tasks of evaluating the integrity of mechanical process elements and structu... more One of the important tasks of evaluating the integrity of mechanical process elements and structures is to determine the local mechanical properties. In this paper, experimental and numerical analyses of the mechanical behavior of an output inter-heater tube, made of 12H1MF heat-resistant steel, was performed after 200,000 h of exploitation. During exploitation, the tube was exposed to various mechanisms of damage including gas corrosion. The tube was cut from a pipe system during reparations of a thermal power plant, and then cold-deformed by bending to obtain a U-bend tube, which was then used in the experiment. For this purpose, a specimen holder made of structural steel S235 was specifically designed to test such a sample. The U-bend tube was then exposed to the external compressive load during the experiment. Experimental research was based on the application of the 3D digital image correlation (DIC), while a finite element method (FEM) was applied in numerical simulation perfo...

International Journal of Minerals, Metallurgy, and Materials

A method of synthesizing Ni-based catalysts supported on α-Al 2 O 3-based foams was developed. Th... more A method of synthesizing Ni-based catalysts supported on α-Al 2 O 3-based foams was developed. The foams were impregnated with aqueous solutions of metal chlorides under an air atmosphere using an aerosol route. Separate procedures involved calcination to form oxides and drying to obtain chlorides on the foam surface. The synthesized samples were subsequently reduced with hydrogen. With respect to the Ni/Al 2 O 3 catalysts, the chloride reduction route enabled the formation of a Ni coating without agglomerates or cracks. Further research included catalyst modification by the addition of Pd, Cu, and Fe. The influences of the additives on the degree of reduction and on the low-temperature reduction effectiveness (533 and 633 K) were examined and compared for the catalysts obtained from oxides and chlorides. Greater degrees of reduction were achieved with chlorides, whereas Pd was the most effective modifier among those investigated. The reduction process was nearly complete at 533 K in the sample that contained 0.1wt% Pd. A lower reduction temperature was utilized, and the calcination step was avoided, which may enhance the economical and technological aspects of the developed catalyst production method.

Chemical Industry

Parts of industrial machines and structures are often exposed to the action of aggressive environ... more Parts of industrial machines and structures are often exposed to the action of aggressive environments, which in a short period of time can provoke the loss of their integrity. It is well known that for extending the service life against erosion and corrosion, protection of the exposed structure zone by coating is frequently used. Various application methods of protective coatings are applied, and the most common are welding and thermal spraying processes. The aim of this study was characterization of coatings made of stainless steel 316L, widely used in chemical and petrochemical industries. The coating was applied on a structural steel S235JR by plasma transferred arc using powder as a filler material. Due to a number of advantages, the plasma transferred arc (PTA) surfacing process has found significant usages in the field of surface protection. This paper presents results of hardness measurements in characteristic zones of the coating and the base material, as well as microstruc...

Srpski arhiv za celokupno lekarstvo

Metallic biomaterials are most commonly used as hard-tissue replacements because of their favorab... more Metallic biomaterials are most commonly used as hard-tissue replacements because of their favorable mechanical features and excellent biocompatibility. The objective of this paper is to present an overview of diverse surface modification techniques, with a special emphasis on the laser surface modification method, as well as diverse characterization techniques used for investigating the impact of the surface modification process on metallic implant materials' properties. Moreover, the effect of laser radiation on the surface its and mechanical characteristics, as well as on the structure of metallic bioimplants, is presented. The study of influence of high-intensity laser radiation on metallic materials' surface includes primarily investigations of the surface morphology modifications and specific surface structure formation since their presence enables enhanced osseointegration.

Archives of Biological Sciences

The biological quality and chemical composition of alloys used in dental practice change during h... more The biological quality and chemical composition of alloys used in dental practice change during heat treatment. Often the residues of the previous cast are not disposed of but are reused and recycled until consumed. Thus, manufactured dental restorations have modified biological quality and chemical composition, and compromised biocompatibility. The aim of this study was to investigate the influence of repeated casting on the cytotoxicity of the silver-palladium (Ag-Pd) alloy. Our results showed that repeated casting of the Ag-Pd dental alloy affected its biocompatibility by promoting toxicity against transformed fibroblasts in a contact-independent manner. A strong decrease in cell proliferation, induction of senescence and massive cell death were observed in cultures exposed only to a medium previously incubated with dental alloy samples. The obtained data indicated that toxicity mediated by the accumulation of the Ag, Pd, Cu and Zn cations released from the Ag-Pd material was enhanced by recasting. The induction of cell senescence and subsequent apoptotic and necrotic death were accompanied by amplified intracellular production of reactive oxygen and nitrogen species, suggesting their involvement in the cell destruction process. Therefore, compromised biocompatibility after recasting with the Ag-Pd alloy can be the cause of serious local cell destruction, as observed in clinical practice.

Srpski arhiv za celokupno lekarstvo

Introduction. Increases in market prices of gold over the last 20 years have led to expansion of ... more Introduction. Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and acceptable prices, have found their place in everyday dental practice. However, within the procedure of making dental prosthetic restorations, the alloys are melted and cast, which leads to changes in their physical, mechanical and biological properties. Objective. The objective of the study was to test biocompatibility of a Ni-Cr dental alloy (WIRON 99) depending on the number of melting and casting processes. Methods. The working method included the testing of cytotoxicity of the alloy obtained by casting after one, after four, and after eight successive processes of melting. Cytotoxicity of samples was tested by means of a 24-hour and a three-day cytotoxicity test, done on L929 fibroblasts. Results. A repeatedly melted and cast alloy shows a reduced biocompatibility and causes specific responses of the t...

Science of Sintering, 2016

The possibility to use natural zeolite-clinoptilolite as a host material for radioactive Cs immob... more The possibility to use natural zeolite-clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200 0 C. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage.

The microstructural analysis of a commercial 2219 alloy modified with a small (Si+Ge) addition wa... more The microstructural analysis of a commercial 2219 alloy modified with a small (Si+Ge) addition was carried out using different analytical techniques. The intermetallic phases characteristic for alloy in the as-cast and artificially aged conditions were determined. The presence of CuAl 2 phase, which cannot be dissolved during solution treatment and various phases containing Cu, Mn, Fe and Si in overaged microstructure indicates that more Cu was removed from the solid solution and did not contribute to hardening. This clearly demonstrates that the beneficial effect of Si and Ge on the age-hardening response is controlled by the actual composition of matrix.

Journal of Mining and Metallurgy, Section B: Metallurgy, 2015

Noble dental alloys are often reused in dental practice by recasting. The aim of this study was t... more Noble dental alloys are often reused in dental practice by recasting. The aim of this study was to determine if repeated casting of high gold dental alloys has a detrimental effect on alloy microstructure, type of porosity, structure and microhardness. Results showed that recasting procedure had a strong effect on the change of alloy porosity type. It was also found that alloy microhardness increased with the increase of the number of recasting cycles. At the same time the grain growth and changes of the solid solution phases in the microstructure were observed.

Materials Science Forum, 2004

Materials Science Forum, 2004

ABSTRACT

Journal of the Serbian Chemical Society, 2015

Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Ele... more Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS) analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exh...

Processing and Application of Ceramics, 2014

The fabrication of SiC-HfC ceramic composite via self-propagating high-temperature synthesis and ... more The fabrication of SiC-HfC ceramic composite via self-propagating high-temperature synthesis and simultaneous consolidation was investigated. Dense composite consisting of alternating layers of SiC and HfC was obtained by spark plasma sintering of stack of SiC cloths covered by electrophoretically deposited HfO 2. The deposited HfO 2 was converted into HfC during sintering. The obtained ceramics was characterized in terms of microstructure, cavitation resistance and oxidation resistance. It was shown that spark plasma sintering is effective way to preserve fibre-like mikrostructure of SiC. The obtained material showed good erosion resistance. The surface layer of HfC transformed to HfO 2 during oxidation of samples and protected SiC from further oxidation.

Modern industrial requirements include not only the usage of constructive materials with good mec... more Modern industrial requirements include not only the usage of constructive materials with good mechanical properties but also materials obtained through environmentally friendly and low-cost processing procedures. Basalt, as a low-cost raw material, is regarded as a good candidate for industrial constructive parts production. In the present study, andesite basalt originated from the deposit site "Donje Jarinje", Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing, and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070, and 1080 °C, and afterward the sintering duration was varied from 30 to 240 min at the optimal sintering temperature of 1060 °C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardn...

Numerous mechanical structures and assemblies have frequent outages because of wear of machine pa... more Numerous mechanical structures and assemblies have frequent outages because of wear of machine parts due to the effects of abrasion and erosion. There are several methods to protect parts from wear and one of them is by applying a protective coating on the endangered area. It is well known that the coatings with carbide distributed in a metallic matrix have an excellent wear resistance. In this paper characterization of three coatings were carried out: coating with tungsten carbide (WC) in NiBSiFe matrix, coating with chromium carbides (CrC) in FeNiSi matrix deposited by plasma transferred arc method (PTA), as well as, coating with WC carbide in CrNiBSi matrix deposited by oxy-acetylene thermal spray process. The above mentioned alloys, before application to the base material, were in a powder state. This paper describes applied coating technologies on a substrate -S235JR steel, powders characteristics, microstructure and properties of coatings, phase composition, and micro hardness of different microconstituents.

Ceramics International, 2014

ABSTRACT Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid... more ABSTRACT Intention of this work was to obtain porous silicon dioxide ceramics by using boric acid as an inexpensive additive at low forming pressure and low sintering temperature. Starting raw material, smectite clay from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid was used as binding and sintering aid in amount of 0.5, 1 and 2 wt%. Powder was compacted by using different pressures: 40, 60 and 80 MPa. Pressed samples were sintered at 850, 1000, 1150, and 1300 degrees C for 4 h in air. A relatively high porosity of nearly 40% is obtained for the samples pressed at 40, 60 and 80 MPa and sintered at 1000 degrees C. Median pore size diameters are in the range of macroporous up to 0.2 mu m and 10 mu m in the samples sintered at 1150 and 1300 degrees C, respectively. X-ray diffraction (XRD), scaning electron microscopy (SEM), and porosimetry measurements were employed to characterize the phases and microstructure of the obtained ceramics. The relations between mechanical characteristics of samples (Young modulus and Poisson ratio) and content of boric acid were studied.

Journal of the Serbian Chemical Society, 2016

The effect of multiple recasting of commercial Co-Cr base dental alloy (Dentalit-C) on its struct... more The effect of multiple recasting of commercial Co-Cr base dental alloy (Dentalit-C) on its structural characteristics and ion release rates in artificial saliva has been investigated. The number of recasting was once, four and eight times. The as-cast microstructure became more uniform as the number of recasting was increased whereby macro and microhardness and electrical conductivity of the castings decreased. Metallic ion release in artificial saliva was monitored in vitro over the period of 22 weeks at the temperature of 37 0C and pH 2.3. Only Co and Fe were evidenced in artificial saliva and their release rates are measured. The ion release rates increases with time. The ion release rate of Fe was larger than Co. The ion release rates increases substantially by increasing the number of recasting.

Novel three-dimensional cobalt powder structures were successfully prepared by electrodeposition.... more Novel three-dimensional cobalt powder structures were successfully prepared by electrodeposition. Electrodeposited cobalt powder was characterized by scanning electron microscopy (SEM) and light microscopy. It was possible to control the morphology and structure of cobalt particles by adjusting process parameters of electrodeposition such as current density and type of working electrode. The morphology and structure of cobalt powders were investigated and the formation mechanism of agglomerate was also discussed.

Chemical Industry

One of the important tasks of evaluating the integrity of mechanical process elements and structu... more One of the important tasks of evaluating the integrity of mechanical process elements and structures is to determine the local mechanical properties. In this paper, experimental and numerical analyses of the mechanical behavior of an output inter-heater tube, made of 12H1MF heat-resistant steel, was performed after 200,000 h of exploitation. During exploitation, the tube was exposed to various mechanisms of damage including gas corrosion. The tube was cut from a pipe system during reparations of a thermal power plant, and then cold-deformed by bending to obtain a U-bend tube, which was then used in the experiment. For this purpose, a specimen holder made of structural steel S235 was specifically designed to test such a sample. The U-bend tube was then exposed to the external compressive load during the experiment. Experimental research was based on the application of the 3D digital image correlation (DIC), while a finite element method (FEM) was applied in numerical simulation perfo...

International Journal of Minerals, Metallurgy, and Materials

A method of synthesizing Ni-based catalysts supported on α-Al 2 O 3-based foams was developed. Th... more A method of synthesizing Ni-based catalysts supported on α-Al 2 O 3-based foams was developed. The foams were impregnated with aqueous solutions of metal chlorides under an air atmosphere using an aerosol route. Separate procedures involved calcination to form oxides and drying to obtain chlorides on the foam surface. The synthesized samples were subsequently reduced with hydrogen. With respect to the Ni/Al 2 O 3 catalysts, the chloride reduction route enabled the formation of a Ni coating without agglomerates or cracks. Further research included catalyst modification by the addition of Pd, Cu, and Fe. The influences of the additives on the degree of reduction and on the low-temperature reduction effectiveness (533 and 633 K) were examined and compared for the catalysts obtained from oxides and chlorides. Greater degrees of reduction were achieved with chlorides, whereas Pd was the most effective modifier among those investigated. The reduction process was nearly complete at 533 K in the sample that contained 0.1wt% Pd. A lower reduction temperature was utilized, and the calcination step was avoided, which may enhance the economical and technological aspects of the developed catalyst production method.

Chemical Industry

Parts of industrial machines and structures are often exposed to the action of aggressive environ... more Parts of industrial machines and structures are often exposed to the action of aggressive environments, which in a short period of time can provoke the loss of their integrity. It is well known that for extending the service life against erosion and corrosion, protection of the exposed structure zone by coating is frequently used. Various application methods of protective coatings are applied, and the most common are welding and thermal spraying processes. The aim of this study was characterization of coatings made of stainless steel 316L, widely used in chemical and petrochemical industries. The coating was applied on a structural steel S235JR by plasma transferred arc using powder as a filler material. Due to a number of advantages, the plasma transferred arc (PTA) surfacing process has found significant usages in the field of surface protection. This paper presents results of hardness measurements in characteristic zones of the coating and the base material, as well as microstruc...

Srpski arhiv za celokupno lekarstvo

Metallic biomaterials are most commonly used as hard-tissue replacements because of their favorab... more Metallic biomaterials are most commonly used as hard-tissue replacements because of their favorable mechanical features and excellent biocompatibility. The objective of this paper is to present an overview of diverse surface modification techniques, with a special emphasis on the laser surface modification method, as well as diverse characterization techniques used for investigating the impact of the surface modification process on metallic implant materials' properties. Moreover, the effect of laser radiation on the surface its and mechanical characteristics, as well as on the structure of metallic bioimplants, is presented. The study of influence of high-intensity laser radiation on metallic materials' surface includes primarily investigations of the surface morphology modifications and specific surface structure formation since their presence enables enhanced osseointegration.

Archives of Biological Sciences

The biological quality and chemical composition of alloys used in dental practice change during h... more The biological quality and chemical composition of alloys used in dental practice change during heat treatment. Often the residues of the previous cast are not disposed of but are reused and recycled until consumed. Thus, manufactured dental restorations have modified biological quality and chemical composition, and compromised biocompatibility. The aim of this study was to investigate the influence of repeated casting on the cytotoxicity of the silver-palladium (Ag-Pd) alloy. Our results showed that repeated casting of the Ag-Pd dental alloy affected its biocompatibility by promoting toxicity against transformed fibroblasts in a contact-independent manner. A strong decrease in cell proliferation, induction of senescence and massive cell death were observed in cultures exposed only to a medium previously incubated with dental alloy samples. The obtained data indicated that toxicity mediated by the accumulation of the Ag, Pd, Cu and Zn cations released from the Ag-Pd material was enhanced by recasting. The induction of cell senescence and subsequent apoptotic and necrotic death were accompanied by amplified intracellular production of reactive oxygen and nitrogen species, suggesting their involvement in the cell destruction process. Therefore, compromised biocompatibility after recasting with the Ag-Pd alloy can be the cause of serious local cell destruction, as observed in clinical practice.

Srpski arhiv za celokupno lekarstvo

Introduction. Increases in market prices of gold over the last 20 years have led to expansion of ... more Introduction. Increases in market prices of gold over the last 20 years have led to expansion of basic dental alloys, which, primarily due to their good mechanical properties and acceptable prices, have found their place in everyday dental practice. However, within the procedure of making dental prosthetic restorations, the alloys are melted and cast, which leads to changes in their physical, mechanical and biological properties. Objective. The objective of the study was to test biocompatibility of a Ni-Cr dental alloy (WIRON 99) depending on the number of melting and casting processes. Methods. The working method included the testing of cytotoxicity of the alloy obtained by casting after one, after four, and after eight successive processes of melting. Cytotoxicity of samples was tested by means of a 24-hour and a three-day cytotoxicity test, done on L929 fibroblasts. Results. A repeatedly melted and cast alloy shows a reduced biocompatibility and causes specific responses of the t...

Science of Sintering, 2016

The possibility to use natural zeolite-clinoptilolite as a host material for radioactive Cs immob... more The possibility to use natural zeolite-clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200 0 C. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage.

The microstructural analysis of a commercial 2219 alloy modified with a small (Si+Ge) addition wa... more The microstructural analysis of a commercial 2219 alloy modified with a small (Si+Ge) addition was carried out using different analytical techniques. The intermetallic phases characteristic for alloy in the as-cast and artificially aged conditions were determined. The presence of CuAl 2 phase, which cannot be dissolved during solution treatment and various phases containing Cu, Mn, Fe and Si in overaged microstructure indicates that more Cu was removed from the solid solution and did not contribute to hardening. This clearly demonstrates that the beneficial effect of Si and Ge on the age-hardening response is controlled by the actual composition of matrix.

Journal of Mining and Metallurgy, Section B: Metallurgy, 2015

Noble dental alloys are often reused in dental practice by recasting. The aim of this study was t... more Noble dental alloys are often reused in dental practice by recasting. The aim of this study was to determine if repeated casting of high gold dental alloys has a detrimental effect on alloy microstructure, type of porosity, structure and microhardness. Results showed that recasting procedure had a strong effect on the change of alloy porosity type. It was also found that alloy microhardness increased with the increase of the number of recasting cycles. At the same time the grain growth and changes of the solid solution phases in the microstructure were observed.

Materials Science Forum, 2004

Materials Science Forum, 2004

ABSTRACT

Journal of the Serbian Chemical Society, 2015

Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Ele... more Cobalt 3D powder particles were successfully prepared by the galvanostatic electrodeposition. Electrodeposited cobalt powder were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS) analysis and SQUID magnetometry. It has been shown that morphology, structure and magnetic properties of cobalt particles are closely associated and can be easily controlled by adjusting process parameters of electrodeposition. Morphology of cobalt powder particles is strongly affected by hydrogen evolution reaction as a parallel reaction to cobalt electrodeposition. Depending on the applied current density, the two types of powder particles were formed: dendrites at lower and spongy-like particles at higher current densities. Morphologies and structures of powder particles are correlated with their magnetic properties, and compared with those of the bulk cobalt. In comparison with the properties of bulk cobalt, the obtained 3D structures exh...

Processing and Application of Ceramics, 2014

The fabrication of SiC-HfC ceramic composite via self-propagating high-temperature synthesis and ... more The fabrication of SiC-HfC ceramic composite via self-propagating high-temperature synthesis and simultaneous consolidation was investigated. Dense composite consisting of alternating layers of SiC and HfC was obtained by spark plasma sintering of stack of SiC cloths covered by electrophoretically deposited HfO 2. The deposited HfO 2 was converted into HfC during sintering. The obtained ceramics was characterized in terms of microstructure, cavitation resistance and oxidation resistance. It was shown that spark plasma sintering is effective way to preserve fibre-like mikrostructure of SiC. The obtained material showed good erosion resistance. The surface layer of HfC transformed to HfO 2 during oxidation of samples and protected SiC from further oxidation.