Effect of low temperature nitriding of 100Cr6 substrates on TiN coatings deposited by IBAD

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOIn this paper we studied the influence of pre-treating the surface of 100Cr6 steel by ion beam nitriding at low temperature (380 degrees C) on the surface topography and wear resistance of thin TiN coatings deposited by reactive ion beam assisted deposition. The specimens were characterized by grazing incidence X-ray diffraction, scanning electron microscopy and atomic force microscopy. The wear resistance of the TiN-coated specimens was evaluated by means of ball on disc tests. The results showed that application of a preliminary ion beam nitriding treatment slightly increased the surface roughness but improved the wear resistance of the 100Cr6 steel due to the formation of a diffusion zone containing the gamma'-Fe4N nitride combined with the TiN coating.In this paper we studied the influence of pre-treating the surface of 100Cr6 steel by ion beam nitriding at low temperature (380 degrees C) on the surface topography and wear resistance of thin TiN coatings deposited by reactive ion beam assisted deposition. The specimens were characterized by grazing incidence X-ray diffraction, scanning electron microscopy and atomic force microscopy. The wear resistance of the TiN-coated specimens was evaluated by means of ball on disc tests. The results showed that application of a preliminary ion beam nitriding treatment slightly increased the surface roughness but improved the wear resistance of the 100Cr6 steel due to the formation of a diffusion zone containing the gamma'-Fe4N nitride combined with the TiN coating.1815458CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSem informaçãoThis work was supported by the NanoCom Network Project, 7th Framework Program – IRSES – Project Nr. 247524. SSV, FA and HP are CNPq fellows

High platelet reactivity in patients with acute coronary syndromes undergoing percutaneous coronary intervention: Randomised controlled trial comparing prasugrel and clopidogrel

Background: Prasugrel is more effective than clopidogrel in reducing platelet aggregation in acute coronary syndromes. Data available on prasugrel reloading in clopidogrel treated patients with high residual platelet reactivity (HRPR) i.e. poor responders, is limited. Objectives: To determine the effects of prasugrel loading on platelet function in patients on clopidogrel and high platelet reactivity undergoing percutaneous coronary intervention for acute coronary syndrome (ACS). Patients: Patients with ACS on clopidogrel who were scheduled for PCI found to have a platelet reactivity ≥40 AUC with the Multiplate Analyzer, i.e. “poor responders” were randomised to prasugrel (60 mg loading and 10 mg maintenance dose) or clopidogrel (600 mg reloading and 150 mg maintenance dose). The primary outcome measure was proportion of patients with platelet reactivity <40 AUC 4 hours after loading with study medication, and also at one hour (secondary outcome). 44 patients were enrolled and the study was terminated early as clopidogrel use decreased sharply due to introduction of newer P2Y12 inhibitors. Results: At 4 hours after study medication 100% of patients treated with prasugrel compared to 91% of those treated with clopidogrel had platelet reactivity <40 AUC (p = 0.49), while at 1 hour the proportions were 95% and 64% respectively (p = 0.02). Mean platelet reactivity at 4 and 1 hours after study medication in prasugrel and clopidogrel groups respectively were 12 versus 22 (p = 0.005) and 19 versus 34 (p = 0.01) respectively. Conclusions: Routine platelet function testing identifies patients with high residual platelet reactivity (“poor responders”) on clopidogrel. A strategy of prasugrel rather than clopidogrel reloading results in earlier and more sustained suppression of platelet reactivity. Future trials need to identify if this translates into clinical benefit

Self-organized 2d Ni Particles Deposited On Titanium Oxynitride-coated Si Sculpted By A Low Energy Ion Beam

Self-ordered Ni nanoparticles grown on TiNxOy-coated crystalline silicon previously sculpted by ion beam bombardment are reported. The samples are obtained following a sequential in situ routine deposition procedure. First, crystalline Si is Xe+ bombarded, generating regular patterns. Second, a thin TiNxOy film is grown on the patterned Si substrate. Immediately, nano-sized nickel particles are deposited by ion beam sputtering and temperature-annealed forming a 2D lattice. The self-organized Ni islands are induced by preferential Ni site nucleation on the coated sculpted Si grooves. © 2014 IOP Publishing Ltd.4719Oates, T.W.H., Aligned metallic nanoparticles on rippled surfaces: Optical characterization using generalized ellipsometry (2012) Appl. Surf. Sci., 258, pp. 9278-9282. , 10.1016/j.apsusc.2011.07.110 0169-4332Zhou, Z., Gao, F., Wayne Goodman, D., Deposition of metal clusters on single-layer graphene/Ru(0 0 0 1): Factors that govern cluster growth (2010) Surf. Sci., 604, pp. 31-L38. , 10.1016/j.susc.2010.03.008 0039-6028Acuña, J.J.S., Marchi, M.C., Alvarez, F., Nickel nanoparticles decoration of ordered mesoporous silica thin films for carbon nanotubes growth (2010) Thin Solid Films, 519, pp. 214-217. , 10.1016/j.tsf.2010.07.119 0040-6090Morales, M., Cucatti, S., Acuña, J.J., Zagonel, L.F., Antonin, O., Hugon, M.C., Marsot, N., Alvarez, F., Influence of the structure and composition of titanium nitride substrates on carbon nanotubes grown by chemical vapour deposition (2013) J. Phys. D: Appl. Phys., 46 (15). , 10.1088/0022-3727/46/15/155308 0022-3727 155308Carey, J.D., Ong, L., Silva, S.R.P., Formation of low-temperature self-organized nanoscale nickel metal islands (2003) Nanotechnology, 14 (11), pp. 1223-1227. , 10.1088/0957-4484/14/11/011 0957-4484 011De Volder, M.F.L., Vidauda, D.O., Meshot, E.R., Tawficka, S., Hart, A.J., Self-similar organization of arrays of individual carbon nanotubes and carbon nanotube micropillars (2010) Microelectron. Eng., 87, pp. 1233-1238. , 10.1016/j.mee.2009.11.139 0167-9317Pankhurst, Q.A., Connolly, J., Jones, S.K., Dobson, J., Applications of magnetic nanoparticlesin biomedicine (2003) J. Phys. D: Appl. Phys., 36 (13), pp. 167-R181. , 10.1088/0022-3727/36/13/201 0022-3727 201Oates, T.W.H., Keller, A., Noda, S., Facsko, S., Self-organized metallic nanoparticle and nanowire arrays from ion sputtered silicon templates (2008) Appl. Phys. Lett., 93. , 10.1063/1.2959080 063106Facsko, S., Dekorsy, T., Trappe, C., Kurz, H., Self-organized quantum dot formation by ion sputtering (2000) Microelectron. Eng., 53, p. 245. , 10.1016/S0167-9317(00)00307-5 0167-9317Zhang, Z., Lagally, M.G., Atomistic processes in the early stages of thin-film growth (1997) Science, 276 (5311), pp. 377-383. , DOI 10.1126/science.276.5311.377Venables, J.A., Rate equation approaches to thin film nucleation kinetics (1973) Phil. Mag., 27, pp. 697-738. , 10.1080/14786437308219242 0031-8086Lewis, B., Campbell, D.S., Nucleation and initial-growth behavior of thin-film deposits (1967) J. Vac. Sci. Technol., 4, pp. 209-218. , 10.1116/1.1492548 0022-5355Hammer, P., Victoria, N.M., Alvarez, F., Electronic structure of hydrogenated carbon nitride films (1998) Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, 16 (5), pp. 2941-2949. , DOI 10.1116/1.581443Madi, C.S., George, H.B., Michael Aziz J, M.J., Linear stability and instability patterns in ion-sputtered silicon (2009) J. Phys.: Condens. Matter, 21 (22). , 10.1088/0953-8984/21/22/224010 0953-8984 224010Hüfner, S., (1996) Photoelectron Spectroscopy: Principles and Applications, 82, pp. 68-69. , 10.1007/978-3-662-03209-1 0171-1873Yeh, J.J., Lindau, I., Atomic subshell photoionization cross sections and asymmetry parameters: 1 ≤ Z ≤ 103 (1985) At. Data Nucl. Data Tables, 32, pp. 1-155. , 10.1016/0092-640X(85)90016-6Joannopoulos, J.D., Lukovsky, G., (1984) Topics in Applied Physics, 56, pp. 61-168Shirley, D.A., High-resolution x-ray photoemission spectrum of the valence bands of gold (1972) Phys. Rev., 5, pp. 4709-4714. , 10.1103/PhysRevB.5.4709 0556-2805 BLacerda, R.G., Do Santos, M.C., Tessler, L.R., Hammer, P., Alvarez, F., Marques, F.C., Pressure-induced physical changes of noble gases implanted in highly stressed amorphous, carbon films (2003) Phys. Rev., 68. , 10.1103/PhysRevB.68.054104 B 054104Ochoa, E.A., Droppa, R., Basso, R.L.O., Morales, M., Cucatti, S., Zagonel, L.F., Czerwiec, T., Alvarez, F., The effect of noble gas bombarding on nitrogen diffusion in steel (2013) Mater. Chem. Phys., 143, pp. 116-123. , 10.1016/j.matchemphys.2013.08.027 0254-0584Castro, M., Gago, R., Vázquez, L., Muñoz-García, J., Cuerno, R., Stress-induced solid flow drives surface nanopatterning of silicon by ion-beam irradiation (2012) Phys. Rev., 86. , 10.1103/PhysRevB.86.214107 B 214107Norris, S.A., Stress-induced patterns in ion-irradiated silicon: Model based on anisotropic plastic flow (2012) Phys. Rev., 86. , 10.1103/PhysRevB.86.235405 B 235405Castro, M., Cuerno, R., Hydrodynamic approach to surface pattern formation by ion beams (2012) App. Surf. Sci., 258, pp. 4171-4178. , 10.1016/j.apsusc.2011.09.008Briggs, D., Seah, M.P., (1993) Practical Surface AnalysisChowdhury, R., Bruno, N., Narayan, J., Yalisove, S.M., Epitaxial Growth of titanium nitride films on (1 0 0) Si (1994) Mechanism of Thin Film EvolutionNarayan, J., Tiwari, P., Chen, X., Singh, J., Chowdhury, F.L., Zheleva, T., Epitaxial growth of TIN films on (1 0 0) silicon substrates by laser physical vapor deposition (1992) Appl. Phys. Lett., 61, pp. 1290-1292. , 10.1063/1.107568Bradley, R.M., Harper, J.M.E., Theory of ripple topography induced by ion bombardment (1988) J. Vac. Sci. Technol., 6, pp. 2390-2395. , 10.1116/1.575561 0734-2101 ABradley, R.M., Nanoscale patterns produced by ion erosion of a solid with codeposition of impurities: The crucial effect of compound formation (2013) Phys. Rev., 87. , 10.1103/PhysRevB.87.205408 B 205408Madi, C.S., Anzenberg, E., Ludwig, K.F., Aziz, M.J., Mass redistribution causes the structural richness of ion-irradiated surfaces (2011) Phys. Rev. Lett., 106. , 10.1103/PhysRevLett.106.066101 066101Norris, S.A., Samela, J., Bukonte, L., Backman, M., Djurabekova, F., Nordlund, K., Madi, C.S., Aziz, M.J., Molecular dynamics of single-particle impacts predicts phase diagrams for large scale pattern formation (2011) Nature Commun., 2, p. 276. , 10.1038/ncomms1280Facsko, S., Bobek, T., Stahl, A., Kurz, H., Dissipative continuum model for self-organized pattern formation during ion-beam erosion (2004) Phys. Rev., 69. , 10.1103/PhysRevB.69.153412 B 153412Castro, M., Cuerno, R., Vazquez, L., Gago, R., Self-organized ordering of nanostructures produced by ion-beam sputtering (2005) Physical Review Letters, 94 (1), pp. 1-4. , http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype= pdf&id=PRLTAO000094000001016102000001&idtype=cvips, DOI 10.1103/PhysRevLett.94.016102, 016102Vogel, S., Linz, S.J., How ripples turn into dots: Modeling ion-beam erosion under oblique incidence (2006) Europhysics Letters, 76 (5), pp. 884-890. , DOI 10.1209/epl/i2006-10349-4Venables, J.A., Doust, T., Kariotis, R., Hull, R., Surface diffusion and niucleation process in thin film formation: The case of Ag/Si(1 1 1) (1987) Initial Stages of Epitaxial Growth, pp. 3-14Rasth, C., Seitsonen, A.P., Scheffler, M., Strain dependence of surface diffusion: Ag on Ag(1 1 1) and Pt(1 1 1) (1997) Phys. Rev., 55, pp. 6750-6753. , 10.1103/PhysRevB.55.6750 0163-1829 BBeer, F.P., Johnston, E.R., Dewolf, J.T., Mazurek, D.F., (2008) Mechanics of MaterialsDumesic, J.A., Stevenson, S.A., Sherwood, R.D., Baker, R.T.K., Migration of nickel and titanium oxide species as studied by in situ scanning transmission electron microscopy (1986) J. Catal., 99 (1), pp. 79-87. , 10.1016/0021-9517(86)90200-9 0021-951

Self-organized 2D Ni particles deposited on titanium oxynitride-coated Si sculpted by a low energy ion beam

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Self-ordered Ni nanoparticles grown on TiNxOy-coated crystalline silicon previously sculpted by ion beam bombardment are reported. The samples are obtained following a sequential in situ routine deposition procedure. First, crystalline Si is Xe+ bombarded, generating regular patterns. Second, a thin TiNxOy film is grown on the patterned Si substrate. Immediately, nano-sized nickel particles are deposited by ion beam sputtering and temperature-annealed forming a 2D lattice. The self-organized Ni islands are induced by preferential Ni site nucleation on the coated sculpted Si grooves.4719Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [12/10127-5

Influence of the process temperature on the steel microstructure and hardening in pulsed plasma nitriding

In this paper we report the influence of temperature (260 to 510 degrees C) on the AISI H13 steel microstructure and hardness in pulsed plasma nitriding processes. The experimental results show that bulk nitrogen penetration is well represented by a temperature-activated law. Even at the lowest studied temperatures, grain boundary diffusion causes nitrogen to move relatively deep in the bulk sample. The microstructure was studied by X-ray diffraction analysis at grazing angle and in the Bragg-Brentano configuration. Scanning Electron Microscopy with spatially resolved Xray energy disperse spectroscopy was also employed to map nitrogen influence on the morphology of the material. Also, surface (frontal) and profiling nano-indentation was utilized to elucidate the effect of the temperature on the nitrited material hardness. (c) 2005 Elsevier B.V. All rights reserved.2014167145245