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Published online by Cambridge University Press: 22 February 2011
The feasibility of strength and reliability improvements of Si3N4 through ion implantations has been studied. The approach has been to implant elements that may chemically combine with themselves to form precipitates after appropriate annealing. These precipitates can improve the strength and reliability of ceramics through the introduction of a compressive stress in the implanted surface layer and/or by modifying the fracture originating machining flaws. Sequential implantations of ion pairs of Ti+ and C+, and Si+ and C+ were performed at energies in the range 46 to 175 keV and at doses of 1×1017 cm-2 for each ion species. Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM) techniques were used to analyze the implanted layer. Strength and reliability were determined from four-point flexure strength measurements. Precipitates of TiN and C were found to form in Ti++C+ and Si++C+ implanted Si3N4 surfaces, respectively. Si++C+ implantation resulted in improvements of both strength and reliability of Si3N4, while Ti++C+ implantations had no effect.