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1. Sequential Processes to Produce N-TiO2 Films Through Rf Plasmas

Author

Valencia-Alvarado R, de la Piedad-Beneitez A, López-Callejas R, Rodríguez-Méndez B G, Mercado-Cabrera A, Peña-Eguiluz R, Muñoz-Castro A E, and de la Rosa-Vázquez J M

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

Using as target a CpTi disk in an atmosphere of argon/oxygen and by rf plasma. First titanium dioxide (TiO2) films were obtained on silicon substrates, and subsequently, these films were doped with nitrogen (N-TiO2). In both processes, along four hours at 390°C of temperature. X-Ray diffraction and Raman spectroscopy confirmed the presence of the nanostructured anatase phase. X-ray photoelectron spectroscopy analyzes indicate that the nitrogen atoms were incorporated into the TiO2 film with ~33.9 at%. The films reach a thickness of 1.25 μm and 40 nm the average uniformity determined by using an atomic force microscope. Finally, UV-Vis diffuse reflectance spectroscopy outcome evaluated ones an energy band gap reduction from 3.17 eV to 2.95 eV corresponding to TiO2 films and N-TiO2 films respectively.

Published
2016
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4. PDBD with continuous liquids flows in a discharge reactor

Author

Rodríguez-Méndez, B G, primary, Gutiérrez-León, D G, additional, Belman-Flores, J M, additional, López-Callejas, R, additional, Valencia-Alvarado, R, additional, Muñoz-Castro, A E, additional, Mercado-Cabrera, A, additional, Peña-Eguiluz, R, additional, and de la Piedad-Beneitez, A, additional

Published
2015
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6. Titanium oxidation by rf inductively coupled plasma

Author

Valencia-Alvarado, R, primary, de la Piedad-Beneitez, A, additional, López-Callejas, R, additional, Barocio, S R, additional, Mercado-Cabrera, A, additional, Peña-Eguiluz, R, additional, Muñoz-Castro, A E, additional, Rodríguez-Méndez, B G, additional, and de la Rosa-Vázquez, J M, additional

Published
2014
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7. The Corrosion Enhancement due to Plasma Post-Oxidation Subsequent to Plasma Nitriding of a Steel AISI 4140.

Author

MUÑOZ-CASTRO, A. E., DE LA PIEDAD-BENEITEZ, A., VALENCIA-ALVARADO, R., LÓPEZ-CALLEJAS, R., MERCADO-CABRERA, A., PEÑA-EGUILUZ, R., and RODRIGUEZ-MENDEZ, B. G.

Subjects
*STEEL alloys, *NITRIDING, *OXIDATION, *PLASMA flow, *MAGNETITE, *X-ray diffraction, *SCANNING electron microscopy, *CORROSION in alloys
Abstract

The corrosion enhancement due to plasma post-oxidation subsequent to plasma nitriding of the samples of low alloy annealed steel AISI 4140 was evaluated. The plasma nitriding was carried out at ≈570 °C for 1-3 h in an atmosphere of 75% H2 and 25% N2. After this process post-oxidation at ≈450 °C in a gas mixture, air and dry air-like was conducted for an hour. The treated samples were characterized using the XRD, SEM, AFM, potentiodynamic polarization and Vickers microhardness tests. The outcome of combined processes showed the presence of ε and γ nitrided phases in the inner compound layer and in the outer one mostly of magnetite phase and barely visible of hematite one without using H2 in the post-oxidation process. Also in these processes, the corrosion potential proved to be lower in the treated specimens than the untreated ones, and the corrosion current decreased up to one order of magnitude when treated in environment air and air-like ambient. [ABSTRACT FROM AUTHOR]

Published
2015
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14. Nitriding of 4140 Annealed Low Alloy Steel in RF Plasma.

Author

DE LA PIEDAD-BENEITEZA, A., MUÑOZ-CASTRO, A. E., VALENCIA-ALVARADO, R., LÓPEZ-CALLEJAS, R., MERCADO-CABRERA, A., PEÑA-EGUILUZ, R., RODRIGUEZ-MENDEZ, B., and BAROCIOB, S. R.

Subjects
*NITRIDING, *ALLOYS, *PLASMA radiofrequency heating, *PLASMA flow, *CORROSION & anti-corrosives
Abstract

The annealed low alloy 4140 steel samples have been nitrided for different treatment periods (1-6 h) in an RF inductive plasma discharge with very low bias voltage (≈400 V). The resulting nitrided layer has been observed by means of an optical microscope whereas the nitride phases have been characterised by X-ray analysis. The corrosion response, assessed by the potentiodynamic tests in the 3.5% NaCl solution, presents both higher noble potential values and lower corrosion rates when compared with the untreated sample. The Vickers microhardness tests values show an appreciable increment compared to that of the untreated sample. The process is characterized by a high overall e  ciency because similar average Vickers tests values were obtained, no matter for how long the treatment was extended. Likewise, the scanning electron micrographs confirmed no appreciable size evolution of the compound layer microstructure at different times of treatment. [ABSTRACT FROM AUTHOR]

Published
2013
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