Hugo Estupiñan

Study of Biomimetic and electrolytic calcium phosphate coating on titanium alloy by laser induced breakdown spectroscopy depth profiling

Depth profile analysis by means of laser induced breakdown spectroscopy (LIBS) was investigated with respect to its potential to measure the thickness of different types of thin calcium phosphate used as biomimetic coatings on Ti6Al4V alloy. The coating thickness is determined from the ratio of the intensities of a calcium line and a titanium line measured at burst energy high enough to penetrate the coating with a single burst. To achieve an ablation depth in the range of the coating thickness of about 10 μm a Nd: YAG laser at 532 nm in single shot mode was used. The achieved thickness resolution is estimated to about 500 nm for coating thicknesses of electrolytically deposited calcium phosphate in the range of 1.0 to 10.0 μm.

Analysis of the Composition of Titanium Oxide Coating by Laser Induced Breakdown Spectroscopy

Laser Induced Plasma Spectroscopy (LIPS or LIBS) is an alternative elemental analysis technology based on the optical emission spectra of the plasma produced by the interaction of high‐power laser with gas, solid and liquid. The increasing popularity of this technique is due to the ease of the experimental set‐up and to the wide fiexibility in the investigated material that does not need any pre‐treatment of the sample before the analysis. In this work, Laser Induced Breakdown Spectroscopy (LIBS) is used to determine the composition of titanium oxide film produced by anodized of Ti6Al4V alloy. We have used Ti lines in the spectral region between 470–520 nm to determine temperature of the plasma generated on anodized surface of Ti6Al4V alloy for temperature determination by Boltzmann plot method. In order to measure the content of oxygen and titanium ratio on the surface the alloy, we have used the oxygen lines 777.194, 777.417 and 777.539 nm, and titanium lines 780.597 and 782.491 nm observed in an ambien...

Velocidad de corrosión de una aleación base plomo en una solución de ácido sulfúrico a diferentes temperaturas

RESUMEN Las baterias de automoviles no solo son afectadas por el uso y desgaste, sino tambien por otros factores como la concentracion del electrolito, la perdida de agua y la temperatura a la que puede estar expuestas, siendo este ultimo el factor de mayor influencia permitiendo asi un incremento en la velocidad de corrosion en las aleaciones de plomo (componentes de la bateria) afectando a su vez el tiempo de servicio. Por consiguiente, para la industria de las baterias de automoviles tipo plomo-acido, es muy importante estudiar el efecto de la temperatura en el funcionamiento de las placas negativa y positiva, durante el proceso de carga y descarga que se llevan a cabo en las baterias durante su vida util, y ademas, al estar expuesta a un electrolito de acido sulfurico. De acuerdo a lo anterior, en este trabajo de grado se estudio la influencia de la temperatura en la velocidad de corrosion sobre la aleacion plomo-antimonio, a traves de las tecnicas electroquimicas: espectroscopia de impedancia electroquimica (EIS), extrapolacion de Tafel, curva potenciodinamica y voltametria ciclica. Las pruebas se realizaron a uno y cinco dias de exposicion en acido sulfurico 0.5 M, a temperaturas de 25 y 65°C en una celda plana con intercambiadores de calor para controlar la temperatura en el equipo GAMRY 600. Los potenciales fueron medidos respecto al electrodo de referencia de calomel saturado, y se utilizo como electrodo auxiliar una barra de grafito. Por ultimo, se realizo un analisis de los productos de corrosion formados por medio de microscopia electronica de barrido (SEM).

Efecto del chitosán en el comportamiento electroquímico de recubrimientos de fosfatos de calcio.

Calcium phosphate coatings on implant are known to accelerate the bone growth and enhance bone fixation. The electrolytic deposition of these bioactive compounds has shown better advantages than the coatings obtained by conventional methods. This method has facilitated the possibility to add chitosan in solution, which is a polysaccharide of natural origin, known to induce a greater cellular proliferation than calcium phosphate. In this paper, calcium phosphate- chitosan coatings on a substratum of Ti6A4V ELI have been obtained and evaluated by Electrochemical Impedance Spectroscopy.

ESTUDIO DE LA DEGRADACIÓN ELECTROLÍTICA DE RECUBRIMIENTOS DE ACIDO POLI L- LÁCTICO SOBRE SUSTRATOS TI6AL4V, EN SBF MEDIANTE VOLTAMETRÍA CÍCLICA Y EIS

From polylactic acid coatings (PLA), the degradation polymer mechanism on substrates Ti6Al4V ELI was made a study, immersed in a simulated body fluid (SBF) by means of electrochemical impedance spectroscopy (EIS) and cyclic voltametry (CV). A comparison between the resistance of load transference of the different samples obtained to different voltage conditions, and the best resistance condition was selected to be put under a degradation analysis by immersion in SBF by a time of 8 days and cyclic voltametry. High values of load transference resistance were obtained that expose the degradation of the PLA film and the growth of TiO2 layer.