Improvement of Strength and Reliability of Structural Ceramics Through Ion Implantations

该计划的目标是通过离子注入提高结构陶瓷的强度和可靠性。方法是通过高剂量离子注入和随后的退火来产生可析出的相。由于这些析出物的存在导致表面压缩应力的产生，注入区域的局部体积膨胀预计会增加强度。如果形成热力学上稳定的沉淀物，那么强度和可靠性将不受温度的影响而增加。如果析出相比基体更硬，则应导致表面硬化。在第一阶段，提出了在氮化硅中共注入硅和碳以及钛和碳，以研究碳化硅和碳化钛析出物的形成。用透射电子显微镜进行了表征。四点弯曲试验提供强度和可靠性数据。

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.