NSF Award
9160355
The objective of this program is to achieve strength and reliability improvements in structural ceramics through ion implantation. The approach is to produce precipitable phases by high dose ion implantation and subsequent annealing. The strength increase is expected from the localized volume expansion of the implanted region due to the presence of these precipitates resulting in the generation of compressive surface stresses. If thermodynamically stable precipitates are formed, then a temperature independent increase in strength and reliability is expected. If the precipitate phase is harder than the matrix, a surface hardening should result. In Phase I, it is proposed to co-implant silicon and carbon, and titanium and carbon into silicon nitride to study the formation of silicon carbide and titanium carbide precipitates. Characterization is performed by using transmission electron microscopy. Four-point-bend testing provides strength and reliability data.
