Browsing by Author "Arizaga, A."
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Item Mechanical properties and structure of Ti-6A1-4V alloy implanted with different light ions(1995-10) Alonso, F.; Arizaga, A.; Quainton, S.; Ugarte, J. J.; Viviente, J. L.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThe effect of N+ and C- implantation on the properties of Ti-6Al-4V alloy is widely documented. However, some authors claim that other light ions, such as O+ or B+, also have an effect on this alloy, improving its mechanical properties. In this work, Ti-6Al-4V alloy samples have been implanted with C+, N+ and O+ light ions. Energies from 50 to 180 keV and doses of the order of 1017 ion cm-2 have been used, keeping the substrate temperature below 500°C. Mechanical properties such as the hardness or elastic recovery have been evaluated by means of microindentation tests, with a loading-unloading cycle at loads up to 10 mN. An increase in surface hardness of more than 100% has been observed in most of the implanted samples. Pin-on-disc wear tests under lubricated conditions have been performed to evaluate and compare the tribological behaviour of implanted samples against ultrahigh molecular weight polyethylene. A decrease in the friction coefficient from 0.1 to 0.05, resulting from ion implantation, has been observed. Unlubricated wear tests using an alumina ball on a Ti-6Al-4V disc have also been carried out. Wear tracks on the Ti-6Al-4V, evaluated by means of optical profilometry and scanning electron microscopy, have shown that implantation can improve the abrasive wear resistance by two orders of magnitude. X-ray photoelectron spectroscopy analyses also were carried out on selected samples, showing the presence of hard phases, such as oxides or carbides, in the implanted samples.Item A study of dual chromium plus carbon ion implantation into high speed steel(1994) Oñate, J. I.; Alonso, F.; Viviente, J. L.; Arizaga, A.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA large volume of data is now available on the implantation of nitrogen ions into a wide range of steels and other materials such as titanium alloys. In some cases, especially when the substrate steel materials consist of hard martensitic structures, the benefits of nitrogen implantation are less significant. A combination of titanium plus carbon ions has often been reported to produce a significant improvement in the tribological properties of bearing and high speed steels. This work reports on dual ion implantation of chromium plus carbon ions into an AISI M3:2 high speed steel, comparing the results with a titanium plus carbon implantation procedure. Implantations were carried out in a high current Danfysik ion implanter on surface ground and polished discs at doses above 1017 ions cm-2 and energies ranging from 40 to about 180 keV to yield selected concentration profiles. Ultramicrohardness tests using a dynamic microprobe, and friction and wear testing, were carried out to evaluate the mechanical properties produced by the treatment. It is shown that this implantation procedure can yield a hardening of up to a factor of 1.2 for the highest carbon dose; this effect is very similar to that observed on multiple energy nitrogen implantation to a combined dose of up to 5.5 × 1017 ions cm-2. The results of friction testing also indicate that a relatively significant reduction from about 0.65 to 0.5 is observed in the coefficient of friction under the conditions investigated. X-ray photoelectron spectroscopy analyses indicated that the chromium and carbon implanted elements can combine forming carbidic bonds, and when the carbon dose is increased the underlying C 1s spectra show carbidic and graphitic bonds.Item Tribological effects of yttrium and nitrogen ion implantation on a precipitation hardening stainless steel(1994-08) Alonso, F.; Arizaga, A.; Garcia, A.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationYttrium, nitrogen and combined yttrium and nitrogen implantations have been carried out on an ASTM A286 precipitation hardening iron base alloy to evaluate the benefits in their tribological behaviour. Microindentation tests have shown a significant 20%-60% increment in hardness on the nitrogen implanted material, with a limited improvement in elastic recovery of the indentation. An abrasive test on the same material has also produced a 50% reduction in scratch depth. Y+ and Y+ + N+ implantations also hardened the material but to a lesser extent. Reciprocating ball on disk friction and wear testing at 400 °C resulted in very severe damage in all cases. X-ray photoelectron spectroscopy analyses combined with Ar sputtering have disclosed that nitrogen is mainly in a nitrided form, yttrium remains oxidized at the surface, below which there is an apparent increase in the metallic bond.