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This paper evaluates the effect of adding glycerol to the electrodeposition bath on the deposition efficiency and characteristics of Ni-Mo coating in concentrations ranging from 0.07 to 0.82 mol.L-1. Evaluation of the corrosion resistance was performed by means of weight loss tests in four different periods of immersion. Electrochemical techniques, such as obtaining polarization curves, linear polarization resistance, corrosion current density, corrosion potential, and electrochemical impedance spectroscopy were applied. Corrosion measurements were obtained in 0.5 mol.L-1 NaCl acid solution and 0.5 mol.L-1 NaOH alkaline solution. The morphology and microstructures of electrodeposited were analyzed using Scanning Electron Microscopy and Spectrometry X-Ray Diffraction. The effect of glycerol on Ni-Mo hardness was evaluated by Vickers microhardness measurements. The presence of glycerol in the electrodeposition bath increased the grain size and decreased the hardness of the coating. However, it promoted the formation of a more compact and less porous coating, increasing the corrosion resistance of the coating. Moreover, the addition of 0.82 mol.L-1 glycerol increases current efficiency, thereby reducing the amount of energy consumed during electroplating.

This work investigates the effect of the addition of glycerol on the microstructure, corrosion resistance, and efficiency of the electrodeposition process of Cu coating in an acid sulphate solution. The morphology and microstructures of electrodeposits were analyzed using Scanning Electron Microscopy (SEM), Spectrometry X-Ray Diffraction (XRD) and laser scanning confocal microscopy (LSCM). Evaluation of the corrosion resistance was performed in 2.0 mol⋅L−1 NaCl by means of weight loss tests and electrochemical techniques. The addition of glycerol resulted in a decrease in grain and crystallite sizes, a decrease in roughness and an increase in the tensile strain of the coating. The deposition efficiency and the corrosion resistance increased with the addition of glycerol exhibiting a maximum value at the concentration of 0.42 mol⋅L−1, increasing the efficiency of electrodeposition by approximately 96%. This is related to the roughness of the coating, which is minimal at this concentration.

Zinc electrodeposition is an economical process of Zn coating compared to conventional galvanic process. The galvanizing process is used in various industrial sectors to protect ferrous alloys during the corrosion process. In buildings, the galvanizing process is widely used to coat mortar protective screens. The electrodeposition of zinc has a relatively low cost compared to other coating materials for the same purpose; however, its corrosion resistance is lower than that of most protective deposits. This study evaluated the effect of adding glycerol to the electrodeposition bath on the corrosion resistance, deposition efficiency, morphology and microstructure of the zinc electrodeposit in concentrations ranging from 0.03 to 0.82 M. The electrodeposition was performed on carbon steel AISI 1020 with a current density of 10 mA.cm-2. The electroplating solution composition was 0.10 M ZnCl2, 2.80 M KCl and 0.32 M H3BO3. Electrodeposition time was 17.56 min, 5 µm thick coating, equivalent to the mass of 7.166E-3 g of zinc on the steel surface. Evaluation of the corrosion resistance was performed by means of the electrochemical tests of Anodic Voltammetry, Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) as well as Weight Loss tests in NaCl 0.5 M in 4 (four) different period of immersion. The morphology and microstructures of electrodeposited were analyzed using the techniques of Scanning Electron Microscopy (SEM) and Spectrometry X-Ray Diffraction (XRD). The presence of glycerol in the electrodeposition bath decreased the deposition efficiency; however, it increased corrosion resistance and promoted the formation of more compact and refined electrodeposited coatings. Moreover, the results showed that the corrosion rate does not vary linearly with the addition of glycerol.

This paper shows the analysis performed on the corrosion parameters of three groups of reinforcing steel bars, two of these coated by electroplating process with Zinc (Zn) and Zinc-Nickel (Zn-Ni), and the other without any coating. It was used reinforced concrete specimens, which ones were grouped and then subjected to two different corrosion accelerating methods: aging wetting/drying cycles and salt spray exposure. Corrosion potential was measured to qualitative monitoring of the process and, after the end of the tests, corrosion rate was estimated by measuring the mass loss, to quantitative analyses. As it was expected, coated bars presented a better performance than the average bars regarding the corrosion resistance in chloride ions containing environments. It was also observed that the drying/ NaCl solution wetting cycles seems to be more severe than salt spray fog apparatus with respect to the acceleration of corrosion process. Resumo O presente trabalho avaliou os parâmetros de corrosão das barras de aço revestidas com Zinco (Zn) e com a liga Zinco-Níquel (Zn-Ni), por eletrodeposição, comparando-as com as tradicionalmente utilizadas, sem revestimento. Para isso, utilizaram-se amostras de concreto armado que foram submetidas a ensaios acelerados de corrosão por ação de cloretos (câmara de névoa salina – “salt spray” e ciclos de imersão e secagem). O potencial de corrosão das armaduras foi medido para monitoramento qualitativo do processo e, após o fim dos ensaios, estimaram-se as taxas de corrosão das barras, através da perda de massa, para análise quantitativa. As barras revestidas com Zn e Zn-Ni se mostraram mais resistentes à corrosão, quando comparadas com as barras convencionais, em ambientes com forte ação de cloretos e o envelhecimento por ciclos se mostrou muito mais eficiente na aceleração do processo de corrosão.

The present article focuses on the current status of research and development concerning corrosion resistance of Fe-Cr-based amorphous alloys and gives suggestions for further investigations aimed at improving the performance of these alloys and recommendations of possible new applications. These materials, which are usually obtained either as glassy bulk material or in coating and ribbon form, show high corrosion resistance and high wear resistance and are also relatively inexpensive compared to other amorphous metallic alloys. These characteristics can lead to promising applications of these alloys in which corrosion resistance and erosion-corrosion resistance are important. This review presents the results obtained in recent years, including the effect of amorphous structure, partial crystallization and composition on corrosion resistance, as well as applications of these alloys. Although advances have been made in studies concerning Fe-Cr-based amorphous alloys, there is an important limitation in terms of using them, which is the issue related to the high Mo content needed to achieve sufficient glass-forming ability and high corrosion resistance, which significantly increases the cost of these alloys. Therefore, the cost/benefit relation of these alloys needs to be improved by studying the effect of composition and structure on corrosion resistance and finding new applications of these alloys. Based on this literature review, possible applications and further investigations of these alloys are suggested.

Reinforced concrete is the main structural material used in the world in the construction of bridges, roads and commercial and residential buildings. One effective method for preventing corrosion of steel reinforcement is the application of galvanic coatings to the reinforcement itself. The present study evaluated the performance of three groups of reinforcing steel bars (black steel, used as a reference and rebars electroplated with Zinc and Zinc-Nickel alloys) to corrosion and adherence to the concrete matrix. For the analysis of corrosion, the specimens were subjected to two different accelerated corrosion tests: salt spray exposure and wet and dry semi-cycles. The corrosion potential was measured for the qualitative monitoring of the corrosion process and the corrosion rate was estimated. In order to evaluate the steel-concrete adherence, the pullout test was used, in accordance with RILEM-CEB-FIP. The results showed that Zinc and Zinc-Nickel coatings increased the durability of the reinforcing bars and the accelerated corrosion test of wetting and drying cycles proved to be more aggressive compared to the salt spray method to evaluate the corrosion process in the reinforced concrete specimens. Additionally, galvanized reinforcement reduced adherence to the concrete matrix.

Due to their maneuverability and operational flexibility, helicopters have become an important alternative means of transport in great metropolitan areas in Brazil in the last decade. Nonetheless, the number of helicopter accidents has increased in parallel. From 2006 to 2015, 211 accidents occurred and 1030 people died. The main aim of this article is to examine the causal factors that lead to the human error in the helicopter accidents which occurred in Brazil between 2006 and 2015 using HFACS. The most frequent HFACS categories were: decision error (68%), skill-based errors (59%), violations (33%), physical environment (15%), issues with inadequate supervision (46%), and organizational processes (15%). By identifying the higher level human errors leading to helicopter accidents, HFACS is useful a tool for accident investigations and accident prevention strategies. The current study provides practical suggestions for top managers for a better helicopter operational safety environment.

Made available in DSpace on 2018-11-26T15:27:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-01. Added 1 bitstream(s) on 2021-07-15T15:00:57Z : No. of bitstreams: 1 S1516-14392015000100098.pdf: 2442351 bytes, checksum: 145aaa62549d0ff382181954dd69f98d (MD5) Rotary-vacuum-filter mud (RVFM) is waste generated during the manufacturing process of titanium dioxide. In this work, RVFM and ceramic bricks containing different ratios of this waste are investigated. The mud samples were characterized using thermal analysis (TG/DTG). The aim of the present work was to determine the effect of adding RVFM on the ceramic properties of clay, such as apparent porosity, water absorption, linear shrinkage and flexural strength, used to produce red ceramics (bricks and roofing tiles). Samples were dried out at 110 degrees C and fired at 800 degrees C, 950 degrees C and 1100 degrees C. The addition of RVFM tends to increase the apparent porosity and water absorption and to decrease the flexural strength of the ceramic specimens. Based on the results, ceramic specimens with 20% RVFM content that are burned at 800 degrees C can not be used as bricks, and ceramic specimens with 20% RVFM content that are fired at 800 degrees C and 950 degrees C can not used as roofing tiles, according to Brazilian standards. Univ Fed Bahia, Dept Mat Sci & Technol, BR-40210630 Salvador, BA, Brazil MILLLENNIUM Inorgan Chem Brasil, Camacari, BA, Brazil ODEBRECHT Ambiental, BR-42810000 Camacari, BA, Brazil State Univ Sao Paulo, Dept Met & Mat Engn, BR-05508010 Sao Paulo, SP, Brazil State Univ Sao Paulo, Dept Met & Mat Engn, BR-05508010 Sao Paulo, SP, Brazil