Resistencia a la corrosión de recubrimientos nanoestructurados de Ti-Zr-Si-N

Esta investigación tiene como objetivo la síntesis y caracterización de recubrimientos nanoestructurados de Ti-Zr-Si-N producidos mediante la técnica de co-sputtering sobre sustratos de acero inoxidable AISI/SAE 316L y la aleación de Ti6Al4V y la posterior evaluación de la resistencia frente a la corrosión a altas temperaturas por medio de la técnica de pérdida de masa de termogavimetría. La caracterización morfológica y estructuras de las películas obtenidas se evaluaron por medio de difracción de rayos X (DRX), microscopía electrónica de barrido (SEM), microscopía de láser confocal, interferometría. Los resultados obtenidos en los ensayos indicaron una adecuada protección frente al mecanismo de corrosión hasta los 100 ciclos, después de este tiempo las películas depositados mostraron fracturas, delaminación y la protección del sustrato finalizóAbstract: The objective of this research is the synthesis and characterization of nanostructured coatings of Ti-Zr-Si-N produced by the co-sputtering technique on substrates of stainless steel AISI / SAE 316L and the alloy of Ti6Al4V and the subsequent evaluation of the resistance against to corrosion at high temperatures by means of the technique of mass loss of thermogavimetry. The morphological characterization and structures of the obtained films were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), confocal laser microscopy, interferometry. The results obtained in the tests indicated an adequate protection against the corrosion mechanism up to 100 cycles, after this time the deposited films showed fractures, delamination and the protection of the substrate finished.Maestrí

EVALUACIÓN DE LA RESISTENCIA A LA OXIDACIÓN DE PELICULAS DE Ti-Zr-Si-N PRODUCIDAS POR COSPUTTERING

Películas delgadas de Ti-Zr-Si-N se depositaron sobre sustratos de acero inoxidable 316 L usando la técnica de co-sputtering reactivo. El análisis de la estructura se realizó mediante difracción de rayos X (DRX), el análisis morfológico se realizó por microscopía electrónica de barrido (MEB) y microscopía óptica 3D. Los estudios de oxidación cíclica se realizaron en un horno en ambiente seco con un total de 300 ciclos, cada uno con una tasa de calentamiento de 46 °C/min hasta lograr una temperatura de 600 °C, la cual fue sostenida durante 30 min y finalmente enfriado a 20 °C/min. Los recubrimientos mejoraron la resistencia a la corrosión del acero inoxidable a altas temperaturas en un 30% debido a la formación de óxidos protectores. En este trabajo se discute el mecanismo de corrosión por oxidación cíclica para los recubrimientos realizados

Effect of nickel and rGO on the photocatalytic properties of Co3 xNixO4 prepared with citric acid and CTAB

This work summarizes the research about Co3 xNixO4 x = 0.0 (0%), 0.01 (1%), and 0.04 (4%) conducted with the addition of reduced graphene oxide, rGO, using two routes: with citric acid R1 (C₆H₈O₇, CA) and cetyltrimethylammonium R2 (C19H42BrN, CTAB) by sol-gel technique. The results show that the composite material ¿with rGO¿ enhanced the photocatalytic degradation of methylene blue (MB). According to the results, incorporating rGO into samples with low Ni concentrations of 1% and 4% and processed at 400 ◦C with R1, significantly increased their specific surface area to 31.372 m2.g-1 and 84.743 m2.g-1, respectively. The XRD technique shows the formation of pure cobalt spinel without associated secondary phases and with complete insertion of Ni into the structure. The presence of CA allows the formation of the oxide at lower temperatures. The results of the magnetic tests suggest that the samples obtained by the two synthesis routes present a paramagnetic behavior. The use of CTAB permits the formation of nanoparticles with low agglomeration. TEM images indicate that the sizes of the nanoparticles obtained in the synthesis are less than 20 nm. Thus, based on Raman spectroscopy, the vibrational modes corresponding to the Co3-xNixO4 structure were studied, identifying a broadening and displacement of the peaks with the addition of Ni. Moreover, the disappearance of the peaks corresponding to rGO and attributed to the coating of Co3-xNixO4 graphene nanoparticles was observed. The adsorption isotherms show the behavior of a mesoporous textured material. The diffuse reflectance indicates that R2 with a 1.72 eV value obtained the material with the smallest gap. In addition, the process identified that the existence of reduced graphene oxide increases the material's specific surface area, which plays a crucial role in MB degradation, outperforming the 4% Ni sample that degraded 39.65% in a two-hour treatment

Evaluation of Ni-Doped Tricobalt Tetroxide with Reduced Graphene Oxide: Structural, Photocatalysis, and Antibacterial Response

Cobalt oxide (Co3O4) nanoparticles were successfully prepared by sol–gel and hydrothermal methods for antibacterial and photocatalytic applications with the addition of 1%, 4% nickel (Ni), and reduced graphene oxide (rGO). The structural and morphological properties of the nanoparticles were obtained by XRD, TEM and FESEM techniques. Cobalt oxide showed typical crystallographic planes to cubic phase and particles with inferior diameter to 30 nm. The Ni-Co3O4 + rGO nanocrystals exhibit a band gap value of 2.0 eV. The bactericidal tests for S. aureus and E. coli revealed that the insertion rGO synthesized by the sol–gel method promoted the antimicrobial activity for both microorganisms. Afterward, the photocatalytic assay for the atrazine contaminant showed significant responses to pesticide removal attributed to the simultaneous adsorption and degradation process. In addition, the sol–gel process found a better response to Ni-Co3O4 in the presence of rGO, indicating a nanocomposite superior synergism