Search

Nickel oxide (NiO) is a binary compound with a lot of applications in the present technology. NiO thin films were deposited by reactive sputtering magnetron under several voltage biases applied in the glass substrates (0, 50, 100, 200, 300, 400 and 500 V). Films were characterized by profilometry, X-ray diffraction, elemental composition and electrical resistivity at room temperature and at low temperatures. The present work showed that despite the insulating behavior of substrate the residual stress was reduced at high biases and the (111) texture was promoted. Electrical resistivity was reduced at high bias and at low temperatures thermal activation of p-type conduction was detected., Comment: 6 pages, in Spanish, Proceeding of XI ESPE Congress held at Sangolqu\'i (Ecuador)

Aluminum and their alloys, after careful treatments, can develop excellent mechanical, tribological, electrical and chemical (high corrosion resistance) properties. However, 7000 series, with Cu in the alloy, have a poor corrosion resistance. On the other hand, aluminum nitride (AlN) has a wurtzitic phase and good thermal stability, optical, electric, piezoelectric, mechanical, tribological, and chemical properties, so the application range is huge. In this paper, AlN deposition on Al 7075 was done using the reactive magnetron sputtering technique in order to verify the aluminum nitride performance as an Al alloy protective film under wear and corrosive processes., Comment: 6 pages, 5 figures, in Spanish

Ion nitriding and ion carburising by plasma discharges are promising techniques in order to modify the surface of austenitic steels. Plasma treatments improve mechanical properties, e.g., hardness and wear resistance. Indeed, these techniques do not change the natural austenitic properties, like corrosion resistance. Hidden parameters of the system are very important in order to do a good characterization and a good experimental reproducibility. In this work a new cathode design has been done and it is placed in a new plasma reactor. The electric field edge effect has been discarded in the austenitic samples thanks to a special lodging procedure. After an experimental validation of this new set-up, a numerical simulation has been carried out. Temperature distribution has been analyzed using the cathode-molecular nitrogen collision method. Under these assumptions, reactor cooling is a key issue. This simulation has been done after the resolution of the Laplace equation with the parallel Jacobi method. Finally, using optical emission spectroscopy it has been verified that the heat transfer mechanism is the conduction and the experimental data have been compared with simulation data., Comment: 11 Congreso Binacional de Metalurgia y Materiales, in Spanish

This thesis was focused on the surface modification with plasma discharge. Austenitic AISI 316L stainless steel sample was carburised under different experimental conditions and mechanical properties have been studied (thickness, lattice parameter, elemental composition, hardness, wear resistance and corrosion resistance). After that, steel substrates have been nitrided or carburised in order to analyse their stability under ion bombardment using a plasma focus device. Helium and deuterium were the gases used in 0, 1, 5, and 10 discharges. Optical and X-ray characterisations were used. Finally, using magnetron sputtering nitrided/carburised samples were coated with an AlN thin film in order to study their stability under long treatments at high temperatures., Comment: Thesis submitted in order to obtain the PhD degree in Physics (16-03-2012). Spanish version