[en] The electronics industry demands stamped parts with high performance. Therefore, punching tools like cutting punches with very high precision have to be used. In the case reported, the punches are mounted in a modular system and have to be resharpened or replaced after a certain number of strokes. To increase the lifetime of the punches made of Vasco Wear steel, implantations with carbon, nitrogen, boron and titanium, and co-implantation with titanium and carbon were performed at energies from 50 keV to 200 keV and 600 keV and 700 keV with different doses in the region of several times 10¹⁸ cm^-2, measured perpendicular to the ion beam. A maximum increase in lifetime of a factor of 3.6 was reached. The surface roughness had a large influence on the increase lifetime and the improvement caused by specific ion species. The maximum improvement was obtained for the lowest surface roughness (R_a=0.04 μm). Therefore, when performing the implants, punches with low surface roughness should be used. The most successful ion species were boron and nitrogen for the lowest surface roughness used (R_a=0.04 μm), and after changing the polishing procedure (R_a=0.14 μm) titanium and nitrogen at medium energies (100-200 keV). High energy implantation (700 keV) resulted in an increase of a factor of 2.1 at lower doses (5.6x10¹⁷ cm^-2), but is uneconomical owing to the low current density. In laboratory wear tests (ball on disk) no improvement by ion implantation could be found. These results prove that it is difficult to compare field tests and laboratory tests because of different testing conditions. (orig.)

[en] Highlights: • A broad overview to existing lattice parameter—T_C data is presented. • A chemical effect of the alkali metals is revealed, besides a known spacing effect. • Several mechanisms for this effect are examined. • The size of this chemical effect is non negligible for fullerides. • Analog impact to other Hubbard Model like systems is expected. - Abstract: Alkali metal doped fullerides (A₃C₆₀) are superconductors with critical temperatures, T_c, extending up to 38 K. T_c is known to depend strongly on the lattice parameter a, which can be adjusted by physical or chemical pressure. In the latter case an alkali atom is replaced by a different sized one, which changes a. We have collected an extensive data base of experimental data for T_c from very early up to recent measurements. We disentangle alkali atom chemical effects on T_c, beyond the well-known consequences of changing a. It is found that T_c, for a fixed a, is typically increased as smaller alkali atoms are replaced by larger ones, except for very large a. Possible reasons for these results are discussed. Although smaller in size than the lattice parameter contribution, the chemical effect is not negligible and should be considered in future physical model developments.