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Anticorrosive evaluation of copper-iron mixtures processed by powder metallurgy

Bautista-Ruiz, Jorge | 2021

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. Material systems were topographically characterized with atomic force microscopy. Corrosion tests were established using potentiodynamic polarization curves. The worn surfaces' characterization was carried out by means of a Confocal Scanning Laser Microscope to complement the study. It was determined that the mixtures' stability and behaviour have different behaviours depending on the evaluated system because the wear system caused, indicating that the phenomenon can be additive. The corrosive phenomenon is dominantly affected by the microstructure of the material. From the results found, it is possible to infer that the best systems evaluated by corrosive contain the highest percentage of copper content. The topographic variation indicates the transition from the active zone to the passive zone of the metal due to electrochemical reactions in the presence of aggressive media.

Determination of the efficiency of hafnium carbide and tantalum carbide coatings deposited on exchange membrane fuel cells

Ruiz Madera, C | 2021-10

Evaluation of the wear-corrosion process in beta-tricalcium(β-TCP) films obtained by physical vapor deposition (PVD)

Bautista-Ruiz, Jorge | 2019

A simultaneous evaluation was done of the wear-corrosion of the coatings of beta-tricalcium phosphate on titanium (Ti) substrate deposits obtained by the magnetron sputtering technique. The characterization was developed by a tribometer system coupled to an electrochemical cell. This system allows the combination of corrosion and friction tests between the surface of the coating and the spherical bone pin. The synergy of the two wear phenomena was characterized, which were monitored by means of the electrochemical response as a function of the value of the friction coefficient. It was determined that the system generates a gradual film accumulation process, followed by an instantaneous loss after a critical period. Additionally, it is concluded that the increase in the coefficient of friction is not immediately followed by the increase in wear rate

Production of electroplated rhenium coatings using pulsating currents

| 2021-06

Rhenium was the most interesting material because it can be oxidized at high temperatures, so it is a promising applicant in biomedical applications. Its high melting point requires techniques such as electro-coating to produce it in thin-film formation, using a current of 40 mA/cm2 , in a cathode pulse and 4 mA/cm2 , in anodic form, the variation in temperature of the acid electrolytic bath being realized in a range of 60 to 85±2 °C. The temperature variation of the samples allowed to correlate their response to the degradation phenomenon. The topographical evaluation using atomic force microscopy on the surface of the samples permitted to indicate that a tendency of the roughness to reduce with the increase of the temperature up to 80 °C existed, an electrochemical evaluation was generated using Tafel polarization curves, immersed in a Ringer's lactate solution with a temperature of 37 °C, has now been subsequently performed using the scanning electron microscope, the surface analysis of the coatings, demonstrating that at deterioration is negligible, but when increasing the temperature to 80 °C, the deterioration is imperceptible when the type of surface damage is unobservable, however in the case of 85 °C the deterioration is observable.

Sliding and corrosion wear of magnetron sputtered tio2 films deposited with different argon and oxygen mixtures

Aperador Chaparro, Willian | 2021-06-15

Were produced TiO2 thin coatings prepared, on substrates pure Titanium using a deposition by magnetron sputtering technique, the percentage of oxygen was varied, to study the behavior in terms of friction coefficient corrosive fluids such as those related to the human body. Electrochemical Impedance Spectroscopy (EIS), wear tests with a tribometer, were performed to obtain the tribo-corrosion mechanism of deterioration, taking into account the dual corrosion wear system. The phases were identified by X-ray Photoelectron Spectroscopy (XPS) high resolution. It is determined through the tests performed that the surface treatment has a different effect for each percentage of oxygen influenced by the simulated body environments. The wear performance analysis indicated that the TiO2 film's protection had increased as the percentage of oxygen in the gas mixture (Ar/O2) varied and other synthesis parameters such as deposition time, target power, and substrate temperature remained constant.

Sol-Gel Synthesis of Titanium/Bismuth Oxide Coatings for Biocompatibility Applications on 316L Stainless Steel

Aperador Chaparro, William Arnulfo | 2018-05

Objectives: This study was carried out in order to establish the potential offered by the sol-gel method to obtain Titanium/ Bismuth oxide coatings on 316L Stainless Steel (SS) substrates in biocompatibility applications. Methods/Analysis: The stable sol was synthesized by using Bismuth nitrate (III) pentahydrate and Titanium (IV) butoxide. The coatings were deposited by spin-coating technique at 4000 rpm and characterized topographically by Scanning Electron Microscopy SEM and structurally by X-ray diffraction XRD. Through the techniques of polarization potentiodynamic curves and Electrochemical Impedance Spectroscopy (EIS), the anticorrosive response of the �ilms was evaluated. The thickness was then measured, and biocompatibility test was developed. Findings: It was found that the coatings with high composition of the precursor titanium (IV) butoxide offer the best results as an anticorrosive application. Likewise, the growth of cells was uniform on the �ilms indicating that the medium offered by the �ilms does not present active cytotoxicity and surpasses by a large number the cellular growth level compared to stainless steel. Applications /Improvement: 316L (SS) is very useful in implantology, for its low cost compared with other materials. The implanted steel suffers corrosion by the physiological �luids of body. Titanium/Bismuth coatings establish a barrier between body �luids and SS implant.

SYNERGISTIC CORROSION-WEAR EFFECT IN AUSTENITIC POWDER METALLURGICAL STEEL WITH DIFFERENT TITANIUM ADDITIONS

Aperador, w | 2022-01-01

To ascertain the influence of titanium percentage in 316L austenitic steel, titanium percentages varied from 0.5 to 2% aggregated to 316L steel. The powder metallurgy method was used. The powdered material was pressed at 800 MPa and then sintered at 1300°C. The X-ray diffraction (XRD) technique was used to characterize the identification of the phases after the processed mixtures. Wear and tribowear properties were determined by pin on disc tests. Electrochemical polarization curves were used to study corrosion. According to the results of the samples, the corrosion resistance of titanium increased to a percentage of 1.5% due to the formation of the phases generated by the mixture. However, it was determined that the most appropriate percentage is 2%, due to the synergistic mode specifically for wear and corrosion resistance, the mechanism is the most adequate.

Synthesis and corrosion resistance evaluation of coatings of SiO2-TiO2-ZrO2-BiO2 on 316L stainless produced by sol-gel

Olaya, Jhon | 2018-10

En este trabajo se presenta la síntesis y la evaluación de la resistencia a la corrosión de recubrimientos de SiO2-TiO2-ZrO2-BiO2 depositados por la técnica de centrifugado sobre acero inoxidable AISI 316L. Los soles se prepararon a partir de una mezcla de precursores orgánicos, como el tetraetoxisilano (TEOS) al 98%, tetrabutóxido de titanio (TBT) al 97%, zirconio (IV) butóxido (TBZ) al 80% en solución 1-butanol y nitrato de bismuto penta-hidratado Bi(NO3)3*5H2O. La resistencia a la corrosión se determinó mediante ensayos de curvas de polarización potenciodinámica y de espectroscopia de impedancia electroquímica (EIS) en una solución electrolítica de 3,5% Wt de NaCl + 0,5 M de H2SO4. A los soles preparados se les caracterizó mediante estudio reológico, de pH en función del tiempo, mediciones de espectroscopia de infrarrojo por transformada de Fourier (FTIR) y calorimetría diferencial de barrido (DSC). Los recubrimientos se caracterizaron mediante difracción de rayos X (XRD), microscopia electrónica de barrido (MEB), espectroscopia de energías dispersivas (EDX), fluorescencia de rayos X (XRF) y medidas de adherencia. Los resultados mostraron que las películas ofrecen una buena resistencia a la corrosión sobre el sustrato metálico disminuyendo los valores de densidades de corriente hasta en un orden de magnitud

Tribocorrosion Behavior of Amorphous Carbon-Silicon Coated Titanium in Biological Medium

Bautista-Ruiz, Jorge | 2018

Studies of materials in biomedical applications have focused on the generation of new biomaterials and the development of surface modifications, mainly of metals. Amorphous silicon containing diamond like carbon DLC-Si coating deposited on titanium substrate with the purpose of studying its biofunctionality. The behavior against the phenomenon of tribocorrosion of coatings DLC-Si deposited on titanium was evaluated, through the plasma-assisted chemical vapor deposition technique. The nanoindentation technique was used to determine the coating mechanical properties. The DLC-Si coatings were structurally analyzed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, the characteristic binding energy for the signal C1s was obtained from XPS. Via XRD results the amorphous structure of DLC-Si coating was determined. The triboelectrochemical results indicate that the coating shows an adequate wear and to corrosion protection when exposed to the synergic mechanism, thus demonstrating the protective coating effect

Wear synergy of copper-iron mixtures processed by powder metallurgy

Operador, W | 2021

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. The X-ray diffraction technique was used to determine the crystalline structure. Material systems were topographically characterized with optical microscopy. Tribology tests were established using a pin on the disk tribometer. It was determined that the stability of the mixture has different behaviors depending on the evaluated system because the wear system caused, indicating that the phenomenon can be additive. The mixed material is characterized by high friction coefficient and high wear due to the samples' specific properties by increasing the amount of iron in the mixture. The systems analyzed indicate that mechanical degradation was mainly reduced. Dimensional variation of the study specimens was evidenced due to the influence of copper in the system. Only the austenitic structure of the steel was observed, which indicates a complete diffusion of the copper.