| Grant number: | 13/05012-7 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | March 01, 2014 |
| End date: | February 28, 2017 |
| Field of knowledge: | Physical Sciences and Mathematics - Physics - Physics of Fluids, Plasma Physics and Electrical Discharge |
| Principal Investigator: | Elidiane Cipriano Rangel da Cruz |
| Grantee: | Rita de Cássia Cipriano Rangel |
| Host Institution: | Universidade Estadual Paulista (UNESP). Campus Experimental de Sorocaba. Sorocaba , SP, Brazil |
| Associated scholarship(s): | 14/24707-9 - Corrosion resistance of plasma treated carbon steel, BE.EP.PD |
Abstract This paper proposes energetically feasible and environmentally friendly methods for the treatment of carbon steel at low-temperature plasmas to improve their performance under corrosive atmospheres. It describes commercial carbon steel plates initially subjected to ablation process to remove the native oxide layer, which does not completely act on the surface due to the existing faults. This procedure will be conducted in radiofrequency plasmas under previously enhanced conditions. Next, a new oxide layer will be grown under controlled conditions in oxygen plasma. The treatment time, the plasma excitation power and the gas pressure in the reactor will be analyzed regarding how they affect the properties on the resulting layer. Scanning electron microscopy, SEM, and atomic force microscopy, AFM, will be used to evaluate the effects of plasma parameters on the morphology and topography of the oxide layer. X-ray photoelectron spectroscopy, XPS, is used to analyze the chemical composition, molecular structure and thickness of the layer formed. The oxide structure and corrosion resistance to steel will be investigated, respectively, by X-ray diffraction and electrochemical impedance spectroscopy, EIS. The second line of research regards carbon steel blades already containing the enhanced oxide layer which are coated with plasma mixtures of hexamethyldisiloxane, oxygen and/or argon. The properties of these coatings according to the power of the excitation signal, the proportion and total gas pressure will be investigated. Infrared spectroscopy is used to investigate the molecular structure of the films while the deposition rate is calculated by the thickness, determined by profilometry. The wettability of the films and the corrosion resistance to the saline solution system will be evaluated, respectively, by the sessile drop method and by EIS. The third line of research regards creating the silica layers from the surface oxidation of the organosilicone films in oxygen plasmas. This procedure aims to provide a simple method to create SiOxCyHz/SiO2 multilayer structures with a lower rate of defects than that obtained by the usually employed methods. The influence of pressure, power and treatment time on the thickness and chemical composition of the layers will be investigated using XPS. The surface morphology and topography will be analyzed by SEM and AFM, respectively. The mechanical strength and corrosion will be determined by nanoindentation tests and EIS. Finally, in the fourth line of research the number of SiOxCyHz/SiO2 layers intercalated on the carbon steel that contains the metal oxide is changed to determine the corrosion resistance and also the physical stability of the multilayer system. Tests will be conducted on the adhesive tape to assess its physical stability and the corrosion resistance will be determined by EIS. The samples submitted to both tests will be inspected by SEM to evaluate the structural conditions after the tests. The multilayer barrier properties will be determined by gas permeability, therefore they will be prepared on polymer membranes. | |
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