TY  - CONF
AU  - Filipović, Suzana
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
AU  - Obradović, Nina
AU  - Curtarolo, Stefano
PY  - 2024
UR  - https://dais.sanu.ac.rs/123456789/16386
AB  - Dual phase high entropy ceramics are attractive due to potential synergetic effects of the constituents on mechanical properties and thermal stability. In this research, dense, dual phase (Hf,Mo,Ti,W,Z) B2-(Hf.Mo.Ti.W,Zr)C powder was synthesized by varying the contents of the transition metals in the final product. The co-synthesis method was used to obtain boride and carbide constituents by boro/ carbothermal reduction of mixtures of oxides and appropriate amounts of carbon black and B4C. Solid solution formation and densification of the reacted powders were done utilizing two step spark plasma sintering or hot pressing processes. Phase compositions of the produced ceramics were identified by x-ray diffraction while chemical compositions were measured using energy dispersive spectroscopy. The final microstructures showed submicron grains due to pining effect of the two phases. Investigation of the mechanical properties showed increasing in Vickers hardness values s up to 48.6 2.2 GPa for applied load of 0.49N for compositions with optimized elemental contents. Room temperature strength was also measured.
PB  - American Ceramic Society
C3  - Abstract Book / 48th International Conference & Exposition on Advanced Ceramics and Composites, January 28–February 2, 2024, Daytona Beach, Florida
T1  - Synthesis and Properties of (Hf,Mo,Ti,W,Zr)B2-(Hf,Mo,Ti,W,Z)C Dual Phase Ceramics
UR  - https://hdl.handle.net/21.15107/rcub_dais_16386
ER  - 

@conference{
author = "Filipović, Suzana and Hilmas, Gregory E. and Fahrenholtz, William G. and Obradović, Nina and Curtarolo, Stefano",
year = "2024",
abstract = "Dual phase high entropy ceramics are attractive due to potential synergetic effects of the constituents on mechanical properties and thermal stability. In this research, dense, dual phase (Hf,Mo,Ti,W,Z) B2-(Hf.Mo.Ti.W,Zr)C powder was synthesized by varying the contents of the transition metals in the final product. The co-synthesis method was used to obtain boride and carbide constituents by boro/ carbothermal reduction of mixtures of oxides and appropriate amounts of carbon black and B4C. Solid solution formation and densification of the reacted powders were done utilizing two step spark plasma sintering or hot pressing processes. Phase compositions of the produced ceramics were identified by x-ray diffraction while chemical compositions were measured using energy dispersive spectroscopy. The final microstructures showed submicron grains due to pining effect of the two phases. Investigation of the mechanical properties showed increasing in Vickers hardness values s up to 48.6 2.2 GPa for applied load of 0.49N for compositions with optimized elemental contents. Room temperature strength was also measured.",
publisher = "American Ceramic Society",
journal = "Abstract Book / 48th International Conference & Exposition on Advanced Ceramics and Composites, January 28–February 2, 2024, Daytona Beach, Florida",
title = "Synthesis and Properties of (Hf,Mo,Ti,W,Zr)B2-(Hf,Mo,Ti,W,Z)C Dual Phase Ceramics",
url = "https://hdl.handle.net/21.15107/rcub_dais_16386"
}

Filipović, S., Hilmas, G. E., Fahrenholtz, W. G., Obradović, N.,& Curtarolo, S.. (2024). Synthesis and Properties of (Hf,Mo,Ti,W,Zr)B2-(Hf,Mo,Ti,W,Z)C Dual Phase Ceramics. in Abstract Book / 48th International Conference & Exposition on Advanced Ceramics and Composites, January 28–February 2, 2024, Daytona Beach, Florida
American Ceramic Society..
https://hdl.handle.net/21.15107/rcub_dais_16386

Filipović S, Hilmas GE, Fahrenholtz WG, Obradović N, Curtarolo S. Synthesis and Properties of (Hf,Mo,Ti,W,Zr)B2-(Hf,Mo,Ti,W,Z)C Dual Phase Ceramics. in Abstract Book / 48th International Conference & Exposition on Advanced Ceramics and Composites, January 28–February 2, 2024, Daytona Beach, Florida. 2024;.
https://hdl.handle.net/21.15107/rcub_dais_16386 .

Filipović, Suzana, Hilmas, Gregory E., Fahrenholtz, William G., Obradović, Nina, Curtarolo, Stefano, "Synthesis and Properties of (Hf,Mo,Ti,W,Zr)B2-(Hf,Mo,Ti,W,Z)C Dual Phase Ceramics" in Abstract Book / 48th International Conference & Exposition on Advanced Ceramics and Composites, January 28–February 2, 2024, Daytona Beach, Florida (2024),
https://hdl.handle.net/21.15107/rcub_dais_16386 .

TY  - JOUR
AU  - Stanfield, Austin D.
AU  - Smith, Steven M.
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Buljak, Vladimir
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15143
AB  - Final-stage sintering was analyzed for nominally phase pure zirconium diboride synthesized by borothermal reduction of high-purity ZrO2. Analysis was conducted on ZrB2 ceramics with relative densities greater than 90% using the Nabarro–Herring stress–directed vacancy diffusion model. Temperatures of 1900°C or above and an applied uniaxial pressure of 50 MPa were required to fully densify ZrB2 ceramics by direct current sintering. Ram travel data were collected and used to determine the relative density of the specimens during sintering. Specimens sintered between 1900 and 2100°C achieved relative densities greater than 97%, whereas specimens sintered below 1900°C failed to reach the final stage of sintering. The average grain size ranged from 1.0 to 14.7 μm. The activation energy was calculated from the slope of an Arrhenius plot that used the Kalish equation. The activation energy was 162 ± 34 kJ/mol, which is consistent with the activation energy for dislocation movement in ZrB2. The diffusion coefficients for dislocation motion that controls densification were 5.1 × 10−6 cm2/s at 1900°C and 5.1 × 10−5 cm2/s at 2100°C, as calculated from activation energy and average grain sizes. This study provides evidence that the dominant mechanism for final-stage sintering of ZrB2 ceramics is dislocation motion.
PB  - Wiley
T2  - Journal of the American Ceramic Society
T1  - Final‐stage densification kinetics of direct current–sintered ZrB2
SP  - 5654
EP  - 5661
VL  - 106
IS  - 10
DO  - 10.1111/jace.19212
UR  - https://hdl.handle.net/21.15107/rcub_dais_15143
ER  - 

@article{
author = "Stanfield, Austin D. and Smith, Steven M. and Filipović, Suzana and Obradović, Nina and Buljak, Vladimir and Hilmas, Gregory E. and Fahrenholtz, William G.",
year = "2023",
abstract = "Final-stage sintering was analyzed for nominally phase pure zirconium diboride synthesized by borothermal reduction of high-purity ZrO2. Analysis was conducted on ZrB2 ceramics with relative densities greater than 90% using the Nabarro–Herring stress–directed vacancy diffusion model. Temperatures of 1900°C or above and an applied uniaxial pressure of 50 MPa were required to fully densify ZrB2 ceramics by direct current sintering. Ram travel data were collected and used to determine the relative density of the specimens during sintering. Specimens sintered between 1900 and 2100°C achieved relative densities greater than 97%, whereas specimens sintered below 1900°C failed to reach the final stage of sintering. The average grain size ranged from 1.0 to 14.7 μm. The activation energy was calculated from the slope of an Arrhenius plot that used the Kalish equation. The activation energy was 162 ± 34 kJ/mol, which is consistent with the activation energy for dislocation movement in ZrB2. The diffusion coefficients for dislocation motion that controls densification were 5.1 × 10−6 cm2/s at 1900°C and 5.1 × 10−5 cm2/s at 2100°C, as calculated from activation energy and average grain sizes. This study provides evidence that the dominant mechanism for final-stage sintering of ZrB2 ceramics is dislocation motion.",
publisher = "Wiley",
journal = "Journal of the American Ceramic Society",
title = "Final‐stage densification kinetics of direct current–sintered ZrB2",
pages = "5654-5661",
volume = "106",
number = "10",
doi = "10.1111/jace.19212",
url = "https://hdl.handle.net/21.15107/rcub_dais_15143"
}

Stanfield, A. D., Smith, S. M., Filipović, S., Obradović, N., Buljak, V., Hilmas, G. E.,& Fahrenholtz, W. G.. (2023). Final‐stage densification kinetics of direct current–sintered ZrB2. in Journal of the American Ceramic Society
Wiley., 106(10), 5654-5661.
https://doi.org/10.1111/jace.19212
https://hdl.handle.net/21.15107/rcub_dais_15143

Stanfield AD, Smith SM, Filipović S, Obradović N, Buljak V, Hilmas GE, Fahrenholtz WG. Final‐stage densification kinetics of direct current–sintered ZrB2. in Journal of the American Ceramic Society. 2023;106(10):5654-5661.
doi:10.1111/jace.19212
https://hdl.handle.net/21.15107/rcub_dais_15143 .

Stanfield, Austin D., Smith, Steven M., Filipović, Suzana, Obradović, Nina, Buljak, Vladimir, Hilmas, Gregory E., Fahrenholtz, William G., "Final‐stage densification kinetics of direct current–sintered ZrB2" in Journal of the American Ceramic Society, 106, no. 10 (2023):5654-5661,
https://doi.org/10.1111/jace.19212 .,
https://hdl.handle.net/21.15107/rcub_dais_15143 .

TY  - JOUR
AU  - Stanfield, Austin D.
AU  - Smith, Steven M.
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Buljak, Vladimir
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15196
AB  - Final-stage sintering was analyzed for nominally phase pure zirconium diboride synthesized by borothermal reduction of high-purity ZrO2. Analysis was conducted on ZrB2 ceramics with relative densities greater than 90% using the Nabarro–Herring stress–directed vacancy diffusion model. Temperatures of 1900°C or above and an applied uniaxial pressure of 50 MPa were required to fully densify ZrB2 ceramics by direct current sintering. Ram travel data were collected and used to determine the relative density of the specimens during sintering. Specimens sintered between 1900 and 2100°C achieved relative densities greater than 97%, whereas specimens sintered below 1900°C failed to reach the final stage of sintering. The average grain size ranged from 1.0 to 14.7 μm. The activation energy was calculated from the slope of an Arrhenius plot that used the Kalish equation. The activation energy was 162 ± 34 kJ/mol, which is consistent with the activation energy for dislocation movement in ZrB2. The diffusion coefficients for dislocation motion that controls densification were 5.1 × 10−6 cm2/s at 1900°C and 5.1 × 10−5 cm2/s at 2100°C, as calculated from activation energy and average grain sizes. This study provides evidence that the dominant mechanism for final-stage sintering of ZrB2 ceramics is dislocation motion.
PB  - Wiley
T2  - Journal of the American Ceramic Society
T1  - Final‐stage densification kinetics of direct current–sintered ZrB2
SP  - 5654
EP  - 5661
VL  - 106
IS  - 10
DO  - 10.1111/jace.19212
UR  - https://hdl.handle.net/21.15107/rcub_dais_15196
ER  - 

@article{
author = "Stanfield, Austin D. and Smith, Steven M. and Filipović, Suzana and Obradović, Nina and Buljak, Vladimir and Hilmas, Gregory E. and Fahrenholtz, William G.",
year = "2023",
abstract = "Final-stage sintering was analyzed for nominally phase pure zirconium diboride synthesized by borothermal reduction of high-purity ZrO2. Analysis was conducted on ZrB2 ceramics with relative densities greater than 90% using the Nabarro–Herring stress–directed vacancy diffusion model. Temperatures of 1900°C or above and an applied uniaxial pressure of 50 MPa were required to fully densify ZrB2 ceramics by direct current sintering. Ram travel data were collected and used to determine the relative density of the specimens during sintering. Specimens sintered between 1900 and 2100°C achieved relative densities greater than 97%, whereas specimens sintered below 1900°C failed to reach the final stage of sintering. The average grain size ranged from 1.0 to 14.7 μm. The activation energy was calculated from the slope of an Arrhenius plot that used the Kalish equation. The activation energy was 162 ± 34 kJ/mol, which is consistent with the activation energy for dislocation movement in ZrB2. The diffusion coefficients for dislocation motion that controls densification were 5.1 × 10−6 cm2/s at 1900°C and 5.1 × 10−5 cm2/s at 2100°C, as calculated from activation energy and average grain sizes. This study provides evidence that the dominant mechanism for final-stage sintering of ZrB2 ceramics is dislocation motion.",
publisher = "Wiley",
journal = "Journal of the American Ceramic Society",
title = "Final‐stage densification kinetics of direct current–sintered ZrB2",
pages = "5654-5661",
volume = "106",
number = "10",
doi = "10.1111/jace.19212",
url = "https://hdl.handle.net/21.15107/rcub_dais_15196"
}

Stanfield, A. D., Smith, S. M., Filipović, S., Obradović, N., Buljak, V., Hilmas, G. E.,& Fahrenholtz, W. G.. (2023). Final‐stage densification kinetics of direct current–sintered ZrB2. in Journal of the American Ceramic Society
Wiley., 106(10), 5654-5661.
https://doi.org/10.1111/jace.19212
https://hdl.handle.net/21.15107/rcub_dais_15196

Stanfield AD, Smith SM, Filipović S, Obradović N, Buljak V, Hilmas GE, Fahrenholtz WG. Final‐stage densification kinetics of direct current–sintered ZrB2. in Journal of the American Ceramic Society. 2023;106(10):5654-5661.
doi:10.1111/jace.19212
https://hdl.handle.net/21.15107/rcub_dais_15196 .

Stanfield, Austin D., Smith, Steven M., Filipović, Suzana, Obradović, Nina, Buljak, Vladimir, Hilmas, Gregory E., Fahrenholtz, William G., "Final‐stage densification kinetics of direct current–sintered ZrB2" in Journal of the American Ceramic Society, 106, no. 10 (2023):5654-5661,
https://doi.org/10.1111/jace.19212 .,
https://hdl.handle.net/21.15107/rcub_dais_15196 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Smith, Steven
AU  - Obradović, Nina
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15224
AB  - High entropy carbide/boride (HEC/HEB) ceramics are materials with a wide range of possible applications in harsh environments due to their good mechanical properties, oxidation resistance, and thermal stability. They are usually formed by the solid solutioning of four or more transition metals (TM) in the boride and carbide lattice. In this research, boro/carbothermal reduction was used to form an individual diboride and carbide phases from oxide mixtures. The stoichiometry of the reaction was varied in order to synthesize pure dual phase ceramics. The reacted powders were spark plasma sintered (SPS) or hot pressed (HP), using a two-step process, to produce dense ceramics and to develop the solid solutions. Ceramics processed by SPS still contained residual oxides, while ceramics produced by HP were nominally phase-pure high entropy dual phase materials. Preferential segregation of the TMs was detected by energy dispersive spectroscopy. Vickers hardness measurements confirmed that the highest hardness was obtained for specimens densified by HP at 1950°C that contained no residual oxides and had the smallest grain size. The hardness increased from 25.7 ± 0.2 GPa to 33.6 ± 2.2 GPa with decrease applied load from 9.81N to 0.49N, respectively.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.
T1  - Optimization of processing parameters for high entropy dual phase ceramics
SP  - 53
EP  - 53
UR  - https://hdl.handle.net/21.15107/rcub_dais_15224
ER  - 

@conference{
author = "Filipović, Suzana and Smith, Steven and Obradović, Nina and Hilmas, Gregory E. and Fahrenholtz, William G.",
year = "2023",
abstract = "High entropy carbide/boride (HEC/HEB) ceramics are materials with a wide range of possible applications in harsh environments due to their good mechanical properties, oxidation resistance, and thermal stability. They are usually formed by the solid solutioning of four or more transition metals (TM) in the boride and carbide lattice. In this research, boro/carbothermal reduction was used to form an individual diboride and carbide phases from oxide mixtures. The stoichiometry of the reaction was varied in order to synthesize pure dual phase ceramics. The reacted powders were spark plasma sintered (SPS) or hot pressed (HP), using a two-step process, to produce dense ceramics and to develop the solid solutions. Ceramics processed by SPS still contained residual oxides, while ceramics produced by HP were nominally phase-pure high entropy dual phase materials. Preferential segregation of the TMs was detected by energy dispersive spectroscopy. Vickers hardness measurements confirmed that the highest hardness was obtained for specimens densified by HP at 1950°C that contained no residual oxides and had the smallest grain size. The hardness increased from 25.7 ± 0.2 GPa to 33.6 ± 2.2 GPa with decrease applied load from 9.81N to 0.49N, respectively.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.",
title = "Optimization of processing parameters for high entropy dual phase ceramics",
pages = "53-53",
url = "https://hdl.handle.net/21.15107/rcub_dais_15224"
}

Filipović, S., Smith, S., Obradović, N., Hilmas, G. E.,& Fahrenholtz, W. G.. (2023). Optimization of processing parameters for high entropy dual phase ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.
Belgrade : Serbian Ceramic Society., 53-53.
https://hdl.handle.net/21.15107/rcub_dais_15224

Filipović S, Smith S, Obradović N, Hilmas GE, Fahrenholtz WG. Optimization of processing parameters for high entropy dual phase ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.. 2023;:53-53.
https://hdl.handle.net/21.15107/rcub_dais_15224 .

Filipović, Suzana, Smith, Steven, Obradović, Nina, Hilmas, Gregory E., Fahrenholtz, William G., "Optimization of processing parameters for high entropy dual phase ceramics" in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023. (2023):53-53,
https://hdl.handle.net/21.15107/rcub_dais_15224 .

TY  - CONF
AU  - Kosanović, Darko
AU  - Filipović, Suzana
AU  - Trajković, Isaak
AU  - Obradović, Nina
AU  - Brune, Paul M.
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15006
AB  - Zirconium diboride(ZrB2) belongs to the group of ultrahigh temperature ceramics (UHTCs) because of its high melting point (3250°C). Due to its excellent properties, such as the melting temperature, high strength and hardness, high thermal and electrical conductivities relative to other ceramics and good corrosion resistance to molten metals, it has attracted great interest from materials scientists. Fully dense ZrB2 ceramics were successfully obtained by hot pressing at 2150oC for 10 minutes. Prior to hot pressing, commercially available ZrB2 powder was ball milled for 24hr with ZrB2 media. Carbon was added as a densification aid in the amount of 0.5 wt.% using phenolic resin. For mechanical testing, three different methods were compared. Three point bending was performed in air at room temperature and the obtained strength was 546±55 MPa. Four-point bend strengths were measured under same conditions resulting in strengths of 476±112 MPa. Finally, the fracture toughness of pure ZrB2 ceramics was determined by the chevron notched beam method to be 4.1 ± 0.5 MPa•m1/2. The obtained results of mechanical testing make this ceramic material applicable as cutting tools, and parts for hypersonic aerospace vehicles.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023
T1  - Mechanical properties of zirconium diboride ceramics
SP  - 84
UR  - https://hdl.handle.net/21.15107/rcub_dais_15006
ER  - 

@conference{
author = "Kosanović, Darko and Filipović, Suzana and Trajković, Isaak and Obradović, Nina and Brune, Paul M. and Hilmas, Gregory E. and Fahrenholtz, William G.",
year = "2023",
abstract = "Zirconium diboride(ZrB2) belongs to the group of ultrahigh temperature ceramics (UHTCs) because of its high melting point (3250°C). Due to its excellent properties, such as the melting temperature, high strength and hardness, high thermal and electrical conductivities relative to other ceramics and good corrosion resistance to molten metals, it has attracted great interest from materials scientists. Fully dense ZrB2 ceramics were successfully obtained by hot pressing at 2150oC for 10 minutes. Prior to hot pressing, commercially available ZrB2 powder was ball milled for 24hr with ZrB2 media. Carbon was added as a densification aid in the amount of 0.5 wt.% using phenolic resin. For mechanical testing, three different methods were compared. Three point bending was performed in air at room temperature and the obtained strength was 546±55 MPa. Four-point bend strengths were measured under same conditions resulting in strengths of 476±112 MPa. Finally, the fracture toughness of pure ZrB2 ceramics was determined by the chevron notched beam method to be 4.1 ± 0.5 MPa•m1/2. The obtained results of mechanical testing make this ceramic material applicable as cutting tools, and parts for hypersonic aerospace vehicles.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023",
title = "Mechanical properties of zirconium diboride ceramics",
pages = "84",
url = "https://hdl.handle.net/21.15107/rcub_dais_15006"
}

Kosanović, D., Filipović, S., Trajković, I., Obradović, N., Brune, P. M., Hilmas, G. E.,& Fahrenholtz, W. G.. (2023). Mechanical properties of zirconium diboride ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023
Belgrade : Serbian Ceramic Society., 84.
https://hdl.handle.net/21.15107/rcub_dais_15006

Kosanović D, Filipović S, Trajković I, Obradović N, Brune PM, Hilmas GE, Fahrenholtz WG. Mechanical properties of zirconium diboride ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023. 2023;:84.
https://hdl.handle.net/21.15107/rcub_dais_15006 .

Kosanović, Darko, Filipović, Suzana, Trajković, Isaak, Obradović, Nina, Brune, Paul M., Hilmas, Gregory E., Fahrenholtz, William G., "Mechanical properties of zirconium diboride ceramics" in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023 (2023):84,
https://hdl.handle.net/21.15107/rcub_dais_15006 .