Banca de DEFESA: JOSÉ ANDERSON MACHADO OLIVEIRA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : JOSÉ ANDERSON MACHADO OLIVEIRA
DATE: 21/01/2021
TIME: 14:00
LOCAL: Remotamente pelo google meet
TITLE:
CHARACTERIZATION OF THE COMPOSITE COATINGS OF CHITOSAN-TUNGSTEN AND CHITOSAN-MOLYBDENUM OBTAINED BY ELECTROPHORETIC DEPOSITION.
KEY WORDS:
Eletrodeposição; Quitosana; Tungstênio; Molibdênio; Corrosão.
PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:
Chitosan is a naturally occurring polysaccharide derived from chitin. It has biocompatible, antibacterial, biodegradable properties, low toxicity, and excellent film formation capacity. Therefore, chitosan-based composite materials or coatings can be applied in different technological and industrial sectors, for example, in the food, cosmetics, textile, biomedicine, and agriculture industries. Due to their mechanical properties and corrosion resistance, tungsten, molybdenum, and their compounds can be used to produce materials with superior properties for applications in environments under extreme operational requirements. Thus, based on the intrinsic properties of chitosan and the metals tungsten and molybdenum, two new composite coatings of chitosan-tungsten (Quit-W) and chitosan-molybdenum (Quit-Mo), obtained by the electrophoretic deposition process, were characterized in this work to evaluate its possible application for protection of metallic structures against corrosion in a medium containing chloride ions (NaCl). The results of morphology (SEM), chemical composition (EDS), crystallography (XRD), and spectroscopy in the infrared region (FT-IR) confirmed the deposition of composite coatings consisting of a film on the micrometric scale, impregnated with metal nanoparticles (tungsten or molybdenum) distributed homogeneously in the chitosan matrix. The results of corrosion resistance, obtained by Potentiodynamic Polarization (PP) and Electrochemical Impedance Spectroscopy (EIS), showed that the composite coatings improved the corrosion resistance of 1020 steel exposed in corrosive NaCl medium (3.5 %). The Quit-W composite coating obtained under the operating conditions of 10 V, pH 5.5, and 10 minutes of deposition showed a corrosion current density (icorr) of 4.0 ± 0.2 µA/cm²; the Quit-Mo composite coating obtained in the conditions of 5 V, pH 5.5, and 10 minutes of deposition (suspension 1: 0.5 g/L of chitosan and 1 mmol/L of sodium molybdate) showed an icorr of 1.4 ± 0.3 µA/cm², thus being the most corrosion-resistant coatings for each evaluated system. Therefore, the results presented here prove the achievement of a new class of chitosan-based composite materials with potential application for the protection of metallic structures against corrosion.
BANKING MEMBERS:
Externa à Instituição - ANA REGINA NASCIMENTO CAMPOS - UFCG
Externo ao Programa - 1753094 - ALCIDES DE OLIVEIRA WANDERLEY NETO
Presidente - 1198847 - JOSE LUIS CARDOZO FONSECA
Externa ao Programa - 2203888 - MARCIA RODRIGUES PEREIRA
Interna - 2413537 - POLLYANA SOUZA CASTRO
Externo à Instituição - RENATO ALEXANDRE COSTA DE SANTANA - UFCG