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RESULTS
Results of the First Stage the Project – 2006
- Equipment for Thermoelectrochemical Treatments – Functional Model
- Equipment for studies of the Flow Accelerated Corrosion processes – Experimental Model
- Documentation for expanding of the research potential of Consortium in Surface Science
Final results
Resources of the integrated technical platform include experimental facilities developed in the frame of MENER Project, “Integrated Laboratory for nuclear material evaluation” upgraded by replacement of the ESCALAB MK II with a new ESCALAB 250 Electron Spectrometer, as well as experimental facilities from the research bases with multiple BCUM utilizers: “National Research Center for fatigue and constructions”, “Research Center for material resistance, mechanical structures safety, cables and conductors”.
The research capabilities in the field of Surface Science (techniques for structures and processes characterization, techniques for surface electrochemical processing), are interconnected in an informational system (SI) with the following functions:
- data acquisition by different experimental techniques used for surfaces and interfaces characterization (ESCA, XRD, LXRD, SEM, AFM, EIS and other electrochemical techniques);
- data acquisition by different electrochemical characterization techniques of material/functioning environment interaction process;
- processing and correlation of experimental data;
- materials and processes diagnosis;
- control of electrochemical reactor used for carbonic films electro deposing.
Integrated activities of partners to the technological integrated platform cover the multidisciplinary scientific and technical activities that start from the designing of the multifunction materials and having as final purpose the integrated technologies for industrial applications. Scheme from Fig. 1 shows the scientific and technical activities which are developing in the frame of the Platform.
The integrated research capacity is utilized for developing of technologies for controlled modification of materials superficial structure, in order to obtain multifunctional advanced materials and to assist the Management Program of lifetime of Cernavoda NPP by developing two pilot projects:
- Integrated Laboratory for electro deposing of carbon films LIECA;
- Control and Prediction System for Flow Accelerated Corrosion Process FAC SCP-FAC.
Results:
- Electrochemical Reactor for Carbonic Film Electro deposition by organic liquids electrolysis (Functional Model);
- Equipment for Thermoelectrochemical treatments (Functional Model).
Fig. 1. Scientific activities developed in the frame of the project
Extensive trials were carried out in order to develop a complex electrochemical treatment of stainless steels to improve the corrosion and tribological performances. The treatment include:
- various nitriding and nitrocarburising plasma electrochemical diffusion processes to modify the steelcsubstrate;
- carbonic films electro-deposition using a method for synthesis of DLC structures at atmospheric pressure and low temperature; a solution of acetylene in liquid ammonia was used as electrolyte;
- carbonic films deposition in Thermionic Vacuum Arc Plasma.
The processes and structures obtained by Electrochemical Surface Engineering Methods, in various experimental conditions, were characterized by correlation of the results of the complementary techniques: XPS, "depth profiling", SEM, XRD, LAXRD, EIS, AFM.
The corrosion behavior was studied by electrochemical techniques, and was correlated to the microstructure and the composition of the surface layers which are strongly depending of the electrical parameters.
The effects of the thermo-electrochemical processes are:
- anodic electrolytic heating: temperatures in the range 800-1200°C are established in 2-3 minutes;
- the diffusion of N and C species in the vapor-gas shell surrounding the anode and the interaction with metalic surface;
- the disconnecting of the voltage applied at anode/ solution interface results in the fast tempering of the steel- anode in the working solution, by fast condensation of the vapor-gas shell;
- after thermo-electrocemical treatment the nitrido-martensitic structure of the low carbon steels is changed.
- Surface films developed by thermoelectrochemical treatments, containing Fe, N, C, and Cr in the case of 403 and 304 stainless steel(used as nuclear structural materials) enssure a good corrosion behaviour;
- Adherent DLC films were formed by duplex treatments which include plasma electrolytic carburization of the austenitic steels and subsequent deposition of thin carbonic films using Thermionic Vacuum Arc Plasma (TVA) processes; further developments related to the improvement of the duplex treatments are required to increase the sp3 bonds concentration in the carbonic layer;
- The polyaniline-polypirrole composite protective coatings were formed on low carbon steels by aqueous electro-polymerization;
- Testing System for Flow Accelerated Corrosion behavior in different environments (Functional Model).
The corrosion behavior testing system, based on electrochemical measurement system Pricepton Applied Research, allows electrochemical behavior testing of the obtained surface structures in different testing medium using potential-static and potential-dynamic techniques; the polarization resistance method is used for the evaluation of the corrosion rate; utilization of a special cell and recirculating system allows the testing of the behavior to accelerated flow corrosion phenomena (Jet Impinging Testing). For diagnosis and prediction GENERA software produced by Intercorr International is used. GENERA software offers a generic frame for solutions development to the material corrosion problems.
The results obtained by surface engineering for different covers types were experimentally analyzed and verified on sample components by using the methods of analysis for tension state and deformation and methodologies and procedures for integrity and liability evaluation.
Integrity and reliability of the structures are two notions wich become compulsory three decades ago for designing of the aircraft and evaluation of the healthy of aircraft in operation.
Our research regarding aero-spatial applications of the surface engineering processes is focused attention on the computational aspects and application methods for fracture analysis (to compute crack propagation) and by using the results to evaluate integrity of structure, fatigue life and periodicity of inspection.
Coupling analytical methods to experimental results forms the basis of consistent structural integrity analysis.
The integrated research capacity of the Technological Platform ELSURFSTRUCT will be utilized for developing of technologies for controlled modification of materials superficial structure, in order to obtain multifunctional advanced materials and to assist the Management Program of lifetime of Cernavoda NPP.
Last update: 19.05.2009
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