IMPROVEMENT OF STRENGTH AND RELIABILITY OF STRUCTURAL CERAMICS THROUGH ION IMPLANTATIONS

THE OBJECTIVE OF THIS PROGRAM IS TO ACHIEVE STRENGTH AND RELIABILITY IMPROVEMENTS IN STRUCTURAL CERAMICS THROUGH ION IMPLANTATIONS. THE APPROACH WILL BE TO PRODUCE PRECIPITABLEPHASES 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. AND, IF THE PRECIPITATE PHASE IS HARDER THAN THE MATRIX, A SURFACE HARDENING MAY RESULT. IN PHASE I, WE PROPOSE TO CO-IMPLANT SI(+) AND C(+), AND TI(+) AND C(+) INTO SI3N4 TO STUDY THE FORMATIONS OF SIC ANDTIC PRECIPITATES. CHARACTERIZATIONS WILL BE PERFORMED BY USING TRANSMISSION ELECTRON MICROSCOPY. FOUR-POINT-BEND TESTING WILL PROVIDE THE STRENGTH AND RELIABILITY DATA.