Electrodeposition and Characterization of Ni-Si Nanocomposite Coatings

In this paper is presented morphological aspects and corrosion behaviour of composite coatings having nickel as metal matrix and silicon as dispersed phase obtained during electrodeposition process of nickel. Silicon mean diameter size of particles particles by 50 nm. The Ni-Si composite coatings were electrodeposited from a suspension silicon particles in aqueous nickel sulphate electrolyte by adding 10 g/L and 20 g/L of silicon particles in the electrolyte solution. The morphological aspects of the coatings and inclusion on particles were investigated using SEM and EDX. As test solution NH4OH 0.5 M (specific coke industry) was used in a three electrode open cell with nickel based nanostructured composite coatings as working electrode (WE), a platinum electrode as counter electrode (CE) and an Ag/AgCl electrode as reference electrode (RE)

Corrosion Behavior of Ni-P Coated Steel Strips

In addition to high hardness, Ni-P coatings obtained by the electroless method are widely used due to their high corrosion resistance. The corrosion resistance depends on the content of phosphorus in the coating. Various phosphorus contents result from changes in pH in the process of obtaining layers. The layers obtained in different working conditions were tested for electrochemical corrosion. Tests were conducted on a potentiostat PGP 201. There were plotted and analyzed the anodic polarization Tafel curves for different phosphorus contents, pH conditions and timeexposure in the coating bath. Analyzing the anodic polarization curves it is noticed that low phosphorus sample shows an almost continuous corrosion process while samples with high phosphorus content have slow corrosion in the 3.5% NaCl testing medium

Corrosion Behavior of Materials Al5083 Alloy, 316L Stainless Steel and A681 Carbon Steel in Seawater

In this paper the corrosion behavior of different materials has been evaluated based on exposure in seawater. The laboratory immersion test technique has been applied to evaluate the effect of seawater on the corrosion behavior of different materials. In three sets of experiments, carbon steels (A681 Type O7), austenitic stainless steels (316L) and aluminium alloys (Al5083) were utilized. The specimens were fixed fully submerged in seawater. The corrosion process was evaluated using weight loss method, open-circuit potential measurements (OCP) and polarization techniques. To determine gravimetric index and the rate of penetration, samples were immersed in corrosive environment for 89 days and weighed periodically. The electrochemical experiments were conducted with a Potentiostat/Galvanostat (PGP 201) analyzer. It was connected to a PC. The Voltamaster software was used for electrochemical data analysis. A three-electrode cell composed of a specimen as a working electrode, Pt as counter electrode, and saturated calomel electrode (SCE) (Hg (l)/ Hg2Cl2 (s)) as a reference electrode were used for the tests. The weight loss tests revealed the lowest corrosion rate values for stainless steel and aluminium alloys, indicating a beneficial use for these materials in marine environments. The potentiodynamic method shows that the lowest corrosion rate in seawater (2.8 μm /year) was obtained for the Al5083 alloy, and the highest value of the corrosion rate (41.67 μm/year) for A681 carbon steel

Corrosion Behavior of Zinc Alloy Layers

The alloying of zinc with some additional elements in specific quantities could be reliably used in the hot-dip coating process. These elements conferr substantially improved performance to the end-product specially by improving corrosion resistance. In this paper the influence of adding different percentages of aluminum and bismuth into the zinc bath was researched. The technological conditions for obtaining zinc-bismuth-aluminium coatings with 0.27% - 0.52% bismuth and 0.11% Al are presented. The degree of microalloying and assimilation in the zinc bath was determined by spectrometric analysis of alloy samples, taken from the melt at different time intervals. Corrosion resistance of the layers was assessed by two types of tests: corrosion behaviour in seawater for a period of five weeks and electrochemical tests in 3% NaCl solution. Both applied corrosion tests show an increase in corrosion resistance to bismuth content increasing and metallographic analysis of samples corroded shows a general corrosion process

Melting-Casting Plant Using Vibrating of Melts in order to Obtain Composite with Technological Utility

This paper presents the obtaining of composites materials with technological utility through vibration technology. In order to obtain these composites, and plant was designed and manufactured. In order to show the possibilities of these technologies, a number of composite samples were produced

Occupational Risk Management in Industry

Occupational risk management is part of the occupational health and safety at workplace. Occupational risk management has a specific component relating to the assessment of the risk and a common component of all types of management including: planning, organizing, implementing, and controlling. Managers must understand the legal and moral liability of their job in ensuring a healthy and safe workplace and to make all necessary efforts to achieve and maintain this goal. Although this action is the responsibility of management, employees also have a role as important in ensuring health and safety at the workplace. The case study approach, this paper aimed to determine if employees respond to the important efforts being made by the organization to reduce the level of risk in the workplace and improve security. The case study was based on questioning of one total of 64 employees in the industrial sector in Galati area Romania. The questionnaire had a total of 24 questions chosen so as to show how well the respondents understood the occupational risk management, the attitude towards risk assessment at the workplace, how vigilant are at the workplace, if they understood measures security and the extent to which they meet

Effect of ZrO2 Nanoparticles on the Mechanical and Anticorrosion Properties of Epoxy Coating

Homogeneous epoxy coatings containing ZrO2 nanoparticles were applied on Grade A naval steel substrates. The morphology of the coating was characterized by optical microscopy and scanning electron microscopy. The effect of nanoparticles on the corrosion resistance of the hybrid coating was investigated by potentiodynamic polarization method. ZrO2 (1 wt.%) doping increased the microhardness of coating up to 15%, from 12.5 (kgf/mm2) to 14.4 (kgf/mm2). The coated steel samples were electrochemically monitorized over the 30 days of immersion in 5 wt.% NaCl solution. As shown by the polarization resistance and corrosion rate, the nanoparticles have a beneficial role, significantly improving the corrosion resistance

Evaluation of Corrosion Behaviour by Gravimetric Method

The study aims to evaluate the corrosion behaviour of two steels: BL245 and S235JR, produced at Liberty Steel Galati. BL245 is an alloy used in the oil and gas industry to manufacture pipes for pipeline transportation systems. S235JR is used to make hot finished hollow sections for construction. Gasoline, diesel and a 3.5% sodium chloride solution were chosen as corrosion environments for this study, considering the field of use of the two alloys (oil and construction). Corrosion assessment was analysed using the gravimetric method, which is based on weighing the samples before and after they were immersed for 7, 14, and 35 days in the above-mentioned corrosion environments. Based on the initial weighing and those recorded after the immersion periods, the mass variation of the samples was determined, and the corrosion rate and penetration index were calculated

Effect of Electrodeposition Parameters on the Morphology, Topography and Corrosion Resistance of Epoxy Resin/Zinc Hybrid Coatings

The paper presents the morphology, topography and corrosion behavior of epoxy resin/zinc hybrid coatings obtained by electrodeposition from zinc sulphate electrolyte. The effect of current density and mean diameter size of polymer particles used for electrodeposition of the epoxy resin/zinc coatings on the morphology, topography and roughness of the surfaces were investigated by Scanning Electron Microscopy and Atomic Force Microscopy. The corrosion behavior of the hybrid coatings in 0.5 M sodium chloride solution was evaluated using electrochemical methods. For microbiological corrosion, the effect of sulphate reducing bacteria (SRB) on the surfaces was evaluated using epifluorescence microscopy. The surface roughness before and after bacteria attachment was evaluated using Atomic force microscopy. Polymer particles provide an influence in restricting the growth of zinc crystals as well as a catalytic role in nucleation sites increase. The results of electrochemical tests indicate a very good corrosion resistance of hybrid coatings comparing with zinc coatings. Epifluorescence images demonstrate that hybrid coating surfaces are slightly attacked by sulphate reducing bacteria