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A resistência à corrosão de eletrodepósitos de Cr e Ni-Mo e a influencia do tratamento térmico na estrutura cristalográfica, na morfologia e nas propriedades de microdureza foram investigados. As caracterizações foram feitas usando as técnicas de microscopia eletrônica de varredura (SEM), difração de raios X (XRD) e energia dispersiva de raios X (EDX). Os ensaios de corrosão foram feitos à temperatura ambiente, em solução de NaCl 10 -1 mol dm -3 e usando a técnica de polarização linear potenciodinâmica. O teor de Mo na camada e a eficiência de corrente aumenta com a concentração do íon molibdato no banho de eletrodeposição, enquanto que a morfologia superficial evolui de rugosa e homogênea para trincada com o aumento do teor de Mo na camada. Os ensaios eletroquímicos de corrosão mostram que os eletrodepósitos de Cr são mais resistentes à corrosão que os eletrodepósitos de Ni-Mo e que todas as camadas estudadas corroem em meio de cloreto. Dentre os eletrodepósitos de Ni-Mo estudados, o de Ni-13Mo foi o que apresentou o comportamento de resistência à corrosão mais nobre. A microdureza do eletrodepósito Ni-13Mo aumenta com o aumento da temperatura de tratamento térmico e está relacionado à formação de fases de Ni, Ni 4 Mo e NiMo, durante o tratamento térmico. Ni-13Mo é um potencial candidato a substituir o Cr em aplicações industriais quando a temperatura de operação for maior que 100 °C e que boas propriedades de microdureza sejam requeridas.The corrosion resistance of electrodeposited Cr and Ni-Mo coatings and the influence of heat treatment on the crystallographic structure, morphology and microhardness properties were investigated here. The characterisations were carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) techniques. Corrosion tests were performed at room temperature in 10 -1 mol dm -3 NaCl solutions and by potentiodynamic linear polarization technique. The Mo content in the layer and current efficiency increased with the molybdate ion concentration in the plating solution, while the surface morphology evolved from rough and homogeneous to cracked surface with the increase of the amount of Mo in the layer. The electrochemical corrosion tests showed that the Cr coatings have better corrosion resistance than the Ni-Mo coatings in chloride medium and that all the studied coatings corrode in chloride medium. Ni-13Mo coating has the nobler corrosion behavior among the studied Ni-Mo coatings. The microhardness of the Ni-13Mo coatings increased as the annealing temperature increased which is related with the precipitation of Ni, Ni 4 Mo and NiMo phases during the heat treatment of this coating. Ni-13Mo coating is a potential substitute for chromium coating in industrial applications when operating at temperatures higher than 100 °C and good microhardness properties are required.

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The influence of functionalized multi-walled carbon nanotubes (fMWCNT) in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF) in different ratios was investigated on the acetaminophen (ACOP) electrochemical determination. The electrochemical behavior of the ACOP exhibited a pair of well-defined redox peaks, suggesting that the reversibility of ACOP was significantly improved in comparison to irreversible oxidation peak on bare GCE. The redox process was controlled by adsorption, involves two electrons and the value of apparent rate constant (k) was equal to 14.7 s ± 3.6 s. The analytical curves were obtained for concentrations of ACOP ranging from 0.3 to 3.0 μmol L. The values of the detection limit were calculated from SWV and found to be 6.73 × 10 mol L. The proposed electrochemical sensor exhibited good stability and reproducibility and was applied for ACOP determination in tablets (Tylenol® and Tylenol®DC) with satisfactory results.

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