ABSTRACT In the present work, PTA welding process was used to investigate the influence of welding parameters on the dilution, microhardness and corrosion resistance of Inconel 625 alloy coatings on the API 5L X70 grade steel. The electrochemical impedance spectroscopy (EIS) and linear potentiodynamic polarization (LPP) measurements were used to study the protection properties of the deposited layer when immersed in a 3.5% NaCl solution. The results of EIS and LPP have shown that the corrosion resistance results were more satisfactory for coatings with higher dilution index. The results also showed that the dilution values D (%)varied from 15.33% to 4.39% at the maximum (18.99 kJ/cm) and the minimum (8.34 kJ/cm) welding energy levels. The most relevant dilution value obtained was 4.39%.

RESUMO Revestimentos metálicos podem ser aplicados para diferentes finalidades, como exemplo, para melhorar as propriedades mecânicas, catalíticas, anticorrosivas ou simplesmente melhorar o aspecto decorativo. Neste trabalho foram obtidas ligas de Ni-Fe pelo processo de eletrodeposição utilizando um banho eletrolítico simples contendo os seguintes reagentes, sulfato de níquel, sulfato de ferro e tartarato de sódio. Como ferramenta de otimização foi utilizado um planejamento experimental completo 22, associado à técnica de metodologia de superfície de resposta (MSR). Foram feitas medidas de composição química, eficiência de corrente, morfologia superficial e medidas eletroquímicas de corrosão. Foi observado que a diminuição do pH favoreceu o aumento do ferro e diminuição do níquel na liga. O teor de ferro influenciou na morfologia da liga. O experimento ótimo apresentou uma resistência à corrosão média de 5471,5 Ω.cm² e uma densidade de corrente de corrosão média de 4,814x10-6 A/cm², este experimento apresentou uma composição percentual em massa de níquel de 70 wt% e de ferro de 30 wt% e uma eficiência de corrente média de 58,7%.

ABSTRACT Metallic coatings can be applied for different purposes, for example to improve the mechanical, catalytic, anticorrosive properties or simply to improve the decorative appearance. In the work the Fe-Ni alloys have been obtained by electrodeposition process using a simple electrolytic bath containing the reagents, nickel sulfate, iron sulfate and sodium tartrate. A complete experimental design 22, associated with the response surface methodology (RSM) technique was used as optimization tool. Chemical composition, current efficiency, surface morphology and electrochemical corrosion measures were performed. It was observed that a decrease in the pH favored an increase in iron and decrease in nickel contents in the alloy. The iron content influenced the alloy morphology. The best experiment showed an average corrosion resistance 5471.5 Ω.cm² and a corrosion current density 4.814x10-6 A/cm². This experiment presented a composition of 70 wt% Ni and 30 wt% Fe in the alloy and an average deposition current efficiency of 58.7%.

A study on optimization of bath parameters for electrodeposition of Fe-W-B alloys from plating baths containing ammonia and citrate is reported. A 2³ full factorial design was successfully employed for experimental design analysis of the results. The corrosion resistance and amorphous character were evaluated. The bath conditions obtained for depositing the alloy with good corrosion resistance were: 0.01 M iron sulfate, 0.10 M sodium tungstate and 0.60 M ammonium citrate. The alloy was deposited at 12% current efficiency. The alloy obtained had Ecorr -0.841 V and Rp 1.463 x 10(4) Ohm cm². The deposit obtained under these conditions had an amorphous character and no microcracks were observed on its surface. Besides this, the bath conditions obtained for depositing the alloy with the highest deposition efficiency were: 0.09 M iron sulfate, 0.30 M sodium tungstate and 0.50 M ammonium citrate. The alloy was deposited at 50% current efficiency, with an average composition of 34 wt% W, 66 wt% Fe and traces of boron. The alloy obtained had Ecorr -0.800 V and Rp 1.895 x 10³ Ohm cm². Electrochemical corrosion tests verified that the Fe-W-B alloy deposited under both conditions had better corrosion resistance than Fe-Mo-B.

A produção de proteínas microbianas sobre a casca de maracujá visando à produção de suplemento protéico para animais é uma alternativa encontrada para o grande desperdício desse resíduo agroindustrial. Através das isotermas de dessorção da casca do maracujá, foi verificado que as condições de umidade inicial para o crescimento de microrganismos neste resíduo por meio da fermentação semi-sólida deverá ser acima de 55% (base úmida) e a faixa de umidade ideal para o armazenamento do resíduo em torno de 5,3% (base úmida).

The microbial protein production on passion fruit peel shell as an animal protein supplement production is an alternative found out to avoid the large wastage of agri-industrial residues. Through the desorption isotherms of passion fruit peel, it is verified that for the microorganism growth by solid-state fermentation on this residue, the initial moisture content condition should be above 55% (wet basis). The ideal moisture content range for residue storage is around 5.3% (wet basis).