Corrosion characteristics of seven varieties of metals—zinc, brass C260, stainless steel 302, stainless steel 316, stainless steel 420, stainless steel 430, and stainless steel 440—in three aqueous media—Atlantic Ocean, Charles River, and deionized waters—were assessed via mass loss methods over 32 weeks, with supplemental data in the form of photomicrographic records. Concurrently, tests were conducted to determine the degree of measurement error resulting from the analytical scale used during corrosion assessment. This was accomplished by using reference samples of each type of metal and a glass vial as the container that held the metal and water samples. These error tests indicated that while the mass error associated with the metal samples was low, the error in mass associated with the vial displayed error margins two orders of magnitude larger than the error margins for the smaller metal samples. Further, control tests and statistical analysis indicated that this variation was the result of some quality inherent to the vial. The metal samples involved in the corrosion assessment experiment generally displayed corrosion characteristics in agreement with trends reported in the literature. Zinc produced the greatest quantity of corrosion residues out of all the metals studied. Brass C260 also developed visible corrosion. For example, brass C260 developed dark green/brown adherent residue and whitish blue-tinted nonadherent residue in Atlantic Ocean water, faint greenish tarnishing and some dark green spots and dots over time in Charles River water, and only faint greenish tarnish in deionized water. In contrast with zinc and brass C260, the stainless steels did not exhibit signs of significant corrosion rates excepting stainless steel 420 (SS420), which displayed pitted features surrounded by multi-colored rings on all of its Atlantic Ocean immersion samples and 25% of its Charles River immersion samples. Atlantic Ocean water generally caused the greatest degree of corrosion for all metals, followed by Charles River water, then deionized water, except in the case of zinc. Residues found on zinc samples immersed in the three different water types were similar to each other in coloration. SS420 samples immersed in different waters also displayed similar-colored residues. Comparisons between the corrosion features of SS420 and the single stainless steel 430 and 440 samples that did show visible corrosion in Atlantic Ocean water suggested that minor compositional variations between stainless steels have little effect on the visual characteristics of the corrosion residues they form. Corrosion rates were calculated using linear regressions of the mass loss data for all metal sample sets. While some of these corrosion rates approached literature-reported values for the metal in question, the distributions of the mass loss data sets indicated that any mass changes that resulted from corrosion were likely too small for the electronic scale to detect. Consequently, it is recommended that future corrosion studies using the mass loss method utilize metal samples similar in size to objects typically found at crime scenes.

Esta Tese apresenta a caracterização espectroscópica, eletroquímica e espectroeletroquímica de blendas condutoras de polianilina. Na primeira parte do trabalho foi realizada a caracterização dos materiais através das espectroscopias vibracionais Raman e infravermelho. Os resultados obtidos através da espectroscopia Raman ressonante indicaram que a conformação e a estrutura química do polímero condutor não sofrem mudanças dentro ou fora das matrizes isolantes. Além disso, demonstra-se que as diferenças de intensidade relativa entre as bandas em 574 e 607 cm-1 da polianilina dopada fornecem o grau da interação física entre os constituintes da blenda, sendo realizado também um estudo da relação entre a intensidade das bandas citadas e a condutividade das diferentes blendas obtidas. Na segunda parte do trabalho foi realizada a aplicação de blendas condutoras de polianilina para a proteção contra a corrosão do ferro e da liga de alumínio A2024. Os resultados obtidos mostraram a boa eficiência das blendas para esta finalidade, conforme comprovado pelas curvas de potencial de circuito aberto e a técnica de voltametria cíclica. Verificou-se que a proteção contra a corrosão depende diretamente da formação de um complexo passivante entre a blenda e o material metálico. Por outro lado, deve-se considerar a presença da barreira física causada pelas blendas, superior à existente quando se utiliza o polímero condutor puro, e que evita a penetração de ânions que promovem a degradação do material metálico. / This work shows the spectroscopic, electrochemistry and spectroelectrochemistry characterization of conducting polyaniline blends. In the first part it was done the characterization of the materials by Raman and infrared vibracional espectroscopies. Using resonance Raman spectroscopy it can be observed that conducting polymer conformation and chemical structure does not changed inside or outside insulating matrices. It was also possible to check that the relative intensities of 574 and 607 cm-1 bands indicate the degree of physical interaction of polymers in the blends, moreover the relationship between intensity of mentioned bands and the conductivity was investigated. In second part it was studied the application of conducting blends for corrosion protection on iron and aluminum alloys A2024. Results obtained showed the good eficiency of these materials, proved by open circuit potential and cyclic voltammetry. It was observed that the protection depends on the formation passive of a film between the coating and the metallic material. On the other hand, the physical barrier of blends are better than pure conducting polymer and decreases the penetration of anions that promote the degradation of metallic materials.

Esta Tese apresenta a caracterização espectroscópica, eletroquímica e espectroeletroquímica de blendas condutoras de polianilina. Na primeira parte do trabalho foi realizada a caracterização dos materiais através das espectroscopias vibracionais Raman e infravermelho. Os resultados obtidos através da espectroscopia Raman ressonante indicaram que a conformação e a estrutura química do polímero condutor não sofrem mudanças dentro ou fora das matrizes isolantes. Além disso, demonstra-se que as diferenças de intensidade relativa entre as bandas em 574 e 607 cm-1 da polianilina dopada fornecem o grau da interação física entre os constituintes da blenda, sendo realizado também um estudo da relação entre a intensidade das bandas citadas e a condutividade das diferentes blendas obtidas. Na segunda parte do trabalho foi realizada a aplicação de blendas condutoras de polianilina para a proteção contra a corrosão do ferro e da liga de alumínio A2024. Os resultados obtidos mostraram a boa eficiência das blendas para esta finalidade, conforme comprovado pelas curvas de potencial de circuito aberto e a técnica de voltametria cíclica. Verificou-se que a proteção contra a corrosão depende diretamente da formação de um complexo passivante entre a blenda e o material metálico. Por outro lado, deve-se considerar a presença da barreira física causada pelas blendas, superior à existente quando se utiliza o polímero condutor puro, e que evita a penetração de ânions que promovem a degradação do material metálico. / This work shows the spectroscopic, electrochemistry and spectroelectrochemistry characterization of conducting polyaniline blends. In the first part it was done the characterization of the materials by Raman and infrared vibracional espectroscopies. Using resonance Raman spectroscopy it can be observed that conducting polymer conformation and chemical structure does not changed inside or outside insulating matrices. It was also possible to check that the relative intensities of 574 and 607 cm-1 bands indicate the degree of physical interaction of polymers in the blends, moreover the relationship between intensity of mentioned bands and the conductivity was investigated. In second part it was studied the application of conducting blends for corrosion protection on iron and aluminum alloys A2024. Results obtained showed the good eficiency of these materials, proved by open circuit potential and cyclic voltammetry. It was observed that the protection depends on the formation passive of a film between the coating and the metallic material. On the other hand, the physical barrier of blends are better than pure conducting polymer and decreases the penetration of anions that promote the degradation of metallic materials.