| Metal vapor vacuum arc (MEVVA) implantation and pulsed high energy density plasma (PHEDP) are new techniques for material surface modification by energetic ions at low temperature. Their processes are relatively simple, and the modified layers are well adhesive to the substrates. In the present dissertation, they are, for the first time, used in the modification of ceramic tools applied in turning metals. And the mechanical properties of the substrates and modified layers were comparatively studied. A few new models about their nanomechanics were proposed. In the first section, a MEVVA implanter was introduced into the surface modification of several ceramic (including Al2O3 and Si3N4) cutting tools implanted by titanium, zirconium and chromium. The optimum implantation processes and doses were determined. For Al2O3 ceramic tools implanted by Zr+ ions, the optimum dose was 1×1017 ions/cm2, and for the others, the optimum doses were all more than 2×1017 ions/cm2. After modification, the nanohardness of the modified ceramics were enhanced by a factor of 13~64%, the maximum increase in Young's modulus measured by nanoindentation was 41%, the maximum increase in bending strength was 66%, and the maximal residual compressive stress was approximately 0.63 GPa. After modification by ion implantation with the optimum doses, the surface of the modified tools was very much smooth, and the average surface roughness (Ra) was lower than 50 nm. The edge life of the modified ceramic tools was enhanced by a factor of 2~12, where the Al2O3 ceramic tools implanted by chromium presented the optimal modification effect. In the second section, the PHEDP technique proposed and a PHEDP coaxial gun were used to modify ceramic cutting tools. At room temperature, TiN, TiCN and (Ti,Al)N coatings were, for the first time, successfully deposited onto WC and Si3N4 tool substrates, and the optimum deposition conditions were determined. Under the optimum conditions, the coated tools showed excellent properties: the residual stresses induced by the processes were relatively small, ranged from -2.0 GPa to +1.5 GPa; the adhesive strength between the coatings and the substrates was very strong, and the critical loads by nanoscratch tests reached at 80~110 mN; the hardness and Young's modulus measured by nanoindentation tests were very large, being about 27 GPa and 450 GPa for TiN-coated tools, 50 GPa and 550 GPa for TiCN-coated tools, and 38 GPa and 650 GPa for (Ti,Al)N-coated tools, respectively; the surfaces of all the coated tools were smooth, and Ra fell in the range of 40～140 nm; the coated WC cutting tools can be used in the turning of hardened CrWMn steel (HRC 58~62) under industrial conditions, and the cutting speeds can be enhanced with a factor of 2~10; the flank wears of the coated WC tools were relatively small, and the edge life of the tools was at lest 35 min; compared with the uncoated tools, the flank wears of the coated Si3N4 ceramic tools were reduced by a factor of 6~10 when they were used in turning hardened CrWMn steel or gray cast iron (HB 220~230).In the last section, the nanoindention mechanics of various ceramic substrates were investigated. It was found that the hardness of bulk materials determined by nanoindentation tests exhibits a peak-load-dependence, and such a peak-load- dependence was analyzed using several empirical or semi-empirical equations. For each material, the true hardness was also determined based on these models, and the true hardness values deduced based on different models are similar with each other. It was found that the Young's modulus, extracted directly using the conventional stiffness equation, also exhibits a peak-load-dependence. The dependence may be attributed to the effect of indenter tip rounding. A new method was then proposed in order to obtain a peak-load-independent modulus. Based on the conical indenter approximation, a new analytical approach was proposed for the description of the unloading data. Analysis showed that the elastic modulus and the hardness determined by...
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