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Full-Text Articles in Materials Science and Engineering
Processing And Mechanical Properties Of Hot-Pressed Zirconium Diboride – Zirconium Carbide Ceramics, Eric W. Neuman, William Fahrenholtz, Gregory E. Hilmas
Processing And Mechanical Properties Of Hot-Pressed Zirconium Diboride – Zirconium Carbide Ceramics, Eric W. Neuman, William Fahrenholtz, Gregory E. Hilmas
Materials Science and Engineering Faculty Research & Creative Works
ZrB2 was mixed with 0.5 wt% carbon and up to 10 vol% ZrC and densified by hot-pressing at 2000 °C. All compositions were > 99.8% dense following hot-pressing. The dense ceramics contained 1–1.5 vol% less ZrC than the nominal ZrC addition and had between 0.5 and 1 vol% residual carbon. Grain sizes for the ZrB2 phase decreased from 10.1 µm for 2.5 vol% ZrC to 4.2 µm for 10 vol% ZrC, while the ZrC cluster size increased from 1.3 µm to 2.2 µm over the same composition range. Elastic modulus was ~505 GPa and toughness was ~2.6 MPa·m½ for all compositions. …
Elevated Temperature Thermal Properties Of Zrb2-B4c Ceramics, Eric W. Neuman, Matthew Thompson, William Fahrenholtz, Gregory E. Hilmas
Elevated Temperature Thermal Properties Of Zrb2-B4c Ceramics, Eric W. Neuman, Matthew Thompson, William Fahrenholtz, Gregory E. Hilmas
Materials Science and Engineering Faculty Research & Creative Works
The elevated temperature thermal properties of zirconium diboride ceramics containing boron carbide additions of up to 15 vol% were investigated using a combined experimental and modeling approach. The addition of B4C led to a decrease in the ZrB2 grain size from 22 µm for nominally pure ZrB2 to 5.4 µm for ZrB2 containing 15 vol% B4C. The measured room temperature thermal conductivity decreased from 93 W/m·K for nominally pure ZrB2 to 80 W/m·K for ZrB2 containing 15 vol% B4C. The thermal conductivity also decreased as temperature increased. For nominally pure ZrB2, the thermal conductivity was 67 W/m·K at 2000 °C …
Pressureless Sintering Of Zirconium Diboride With Carbon And Boron Carbide Nanopowder, Eric W. Neuman, Gregory E. Hilmas, William Fahrenholtz
Pressureless Sintering Of Zirconium Diboride With Carbon And Boron Carbide Nanopowder, Eric W. Neuman, Gregory E. Hilmas, William Fahrenholtz
Materials Science and Engineering Faculty Research & Creative Works
Zirconium diboride ceramics with and without carbon and boron carbide nano powder additives were prepared by ball milling with ZrB2 grinding media and pressureless sintering. Additions of up to 1 wt% nano-B4C and 0.5 wt% C were made to the ZrB2 powder. The materials were then sintered between 1800 and 2300 °C for between 90 and 360 min in an Ar/10H2 atmosphere. After sintering at 2200 °C for 90 min, densities ranged from 88.3 to 90.7% for the ZrB2 with 0–1.0% nano-B4C addition. Carbon additions of 0.5 wt% and nano-B4C additions from 0 to 1.0 wt% resulted in densities ranging …
Solid-State Formation Mechanisms Of Core–Shell Microstructures In (Zr,Ta)B2 Ceramics, Anna N. Dorner, Frédéric Monteverde, William Fahrenholtz, Gregory E. Hilmas
Solid-State Formation Mechanisms Of Core–Shell Microstructures In (Zr,Ta)B2 Ceramics, Anna N. Dorner, Frédéric Monteverde, William Fahrenholtz, Gregory E. Hilmas
Materials Science and Engineering Faculty Research & Creative Works
Transition metal diborides with core–shell microstructures have demonstrated excellent mechanical properties at elevated temperatures. Previous studies concluded that core–shell microstructures were formed by liquid-assisted mass transport mechanisms, but in this study, we propose a solid-state formation mechanism for core-shell microstructures in (Zr,Ta)B2 ceramics produced by reaction hot pressing and in ZrB2-TaB2 diffusion couples. Diffusion couple experiments demonstrated that core–shell microstructures developed as a result of Ta diffusion along ZrB2 grain boundaries, which occurred concurrently with lattice diffusion of Ta into ZrB2. These findings suggest that with optimization of batching and processing parameters, core–shell diboride materials may be formed through solid-state …