IMPROVED MECHANICAL PROPERTIES OF DIAMONDS BY ION IMPLANTATION

DIAMONDS ARE NATURE'S HARDEST SUBSTANCE AND IN ADDITION TO THEIR VALUE AS GEMS, THEY ARE OF IMPORTANCE FOR ABRASIVE GRINDING APPLICATIONS, WITH SYNTHETIC DIAMONDS BEING INCREASINGLY USED FOR THE PAST THIRTY YEARS. NITROGEN IS THE MAJOR IMPURITY OF DIAMONDS (UP TO 0.3 AT.%) AND PLAYS A MAJOR ROLE IN INFLUENCING THEIR OPTICAL AND MECHANICAL PROPERTIES. ION IMPLANTATION OF DIAMOND HAS BEEN STUDIED BYA NUMBER OF RESEARCHERS FOR ELECTRICALLY DOPING BUT THERE ARE ONLY TWO KNOWN REPORTS IN THE LITERATURE WHICH ADDRESS THE MECHANICAL PROPERTIES OF IMPLANTED DIAMONDS. BRITISH WORKERS (1) FIND THAT B-AND N-IMPLANTED DIAMONDS HAD SIGNIFICANTLY IMPROVED MECHANICAL BEHAVIOR IN BOTH LABORATORY WEAR TESTS AND INDUSTRIAL MACHINING TESTS. A RECENT REPORT FROM CHINA(2) SUGGESTS THAT IMPLANTATION REDUCES MICROCLEAVAGING THOUGHT TO BE AN IMPORTANT WEAR MECHANISM OF DIAMOND. THESE STUDIES, ALTHOUGH PROVOCATIVE, RAISE MORE QUESTIONS THAN THEY ANSWER. THE PRESENT PROPOSAL ADDRESSES MANY OF THE UNANSWERED QUESTIONS OF WHEN AND WHY DOES IMPLANTATION IMPROVE THE MECHANICAL PROPERTIES OF DIAMOND. NITROGEN AND BORON IMPLANTATIONS WILL BE PERFORMED AT BOTH AMBIENT AND ELEVATED TEMPERATURES TO ENCOURAGE NITROGEN AGGREGATION AND ANNEAL OUT RADIATION DAMAGE, WHICH LEADS TO GRAPHITIZATION AT EXCESSIVE DOSES. IMPLANTATION PARAMETERS (ION SPECIES, DOSE, ENERGIES) WILL BE CORRELATED WITH MECHANICAL PROPERTY CHANGES (FRICTION AND WEAR) IN PHASE I.