About this Abstract |
Meeting |
MS&T22: Materials Science & Technology
|
Symposium
|
Manufacturing and Processing of Advanced Ceramic Materials
|
Presentation Title |
Doping Alumina with Carbon? |
Author(s) |
Li-or Cohen, Priyadarshini Ghosh, Rachel Marder, Wayne D. Kaplan |
On-Site Speaker (Planned) |
Wayne D. Kaplan |
Abstract Scope |
Alumina (α-Al2O3) is commonly sintered in air, but several sintering techniques such as spark plasma sintering (SPS) use graphite dies. Alumina sintered in graphite furnaces often has a dark grey or even black color, and there is debate in the literature regarding the actual role of carbon on sintering and grain growth. The solubility limit of carbon in 99.99% pure alumina equilibrated at 1600°C under flowing He in a graphite furnace was measured using a wavelength dispersive spectrometer mounted on a scanning electron microscope. The solubility limit of carbon in alumina was found to be 3940 at. ppm, and it is believed that at low oxygen partial pressures carbon-hydrogen species substitutes oxygen which is charge-compensated by oxygen vacancies. Doping alumina with carbon at concentrations below the solubility limit does not impede densification and reduces grain growth. Doping above the solubility limit hinders densification during sintering. |