Hydrothermal electrochemical processes. Techniques for functional coatings

Transcription

1 Hydrothermal electrochemical processes. Techniques for functional coatings Presentation by: Drd. Cosmin Petrica, dr. Madalina Popescu, dr. Roxana Piticescu, National R&D Institute for Non-ferrous and Rare Metals, Pantelimon, Ilfov, Romania 1

2 Definition Hydrothermal electrochemical method Hydrothermal synthesis refers to any heterogeneous reaction in the presence of aqueous solvents or mineralizers under high pressure high temperature (HPHT) conditions to dissolve and recrystallize (recover) materials that are relatively insoluble under ordinary conditions. Also, hydrothermal synthesis was defined as the heterogeneous reactions in aqueous media, in a closed system above 100 C and 1 bar or above room temperature and a pressure greater than 1 atm [K. Byrappa, M. Yoshimura, Handbook of Hydrothermal Technology, 2 nd Ed., Elsevier, 2013]. Hydrothermal-electrochemical technique combines hydrothermal process with electrochemical method and consists in electrodeposition of highly crystalline thin films on metallic substrate (working electrode), directly from nanostructured products of hydrothermal reaction. It is particularly important in the case of crystalline oxide products which can not precipitate out of solution in the absence of an applied electric potential. This method refers to the reaction between species included in the electrolytic solution and the substrate being used as an electrode of the electrolytic cell under hydrothermal conditions [K. Byrappa, M. Yoshimura, Handbook of Hydrothermal Technology, 2 nd Ed., Elsevier, 2013]. Advantages hydrothermal-electrochemical method is very convenient for preparing a wide range of films on substrates, coating of materials, preparation of multilayered compounds, functionally graded materials, etc. high versatility: a variety of compounds can be obtained using this technique, such as perovskites, tungstates, molybdates, solid solutions of alkaline earth titanates, etc. short reaction time of electrochemical process; working electrode can be a 2D or 3D metallic substrate. Drawback hydrothermal-electrochemical technique can not be applied for coating of large surfaces. 2

3 Schematic drawing of hydrothermal-electrochemical technique Figure 1. Hydrothermal electrochemical system. 1. colloidal solutions; 2. Cortest autoclave (300 C, 250 atm); 3. autoclave insulation; 4. Teflon vessel; 5. mounting bracket for working electrode (copper); 6. working electrode, WE (Si; Ti;); 7. auxiliary electrode, CE (Pt coated Nb); 8. gold wire (electrical contact); 9. reference electrode, RE (Ag/AgCl); 10. pressure equalizer tap; 11. security valve; 12. manometer; 13. potentiostat / galvanostat PGZ 100; 14. booster HVB 100; 15. computer, software VoltaMaster 4; 16. programmer PID. 3

4 Technological flow working principle mode 4

5 Examples of thin films prepared using hydrothermalelectrochemical technique. (Ba, Sr)TiO 3 deposited on Si/SiO 2 /Ti/Au substrate Potential Cyclic Voltammetry (100 mv/s) Chrono Amperometry ( mv) 5

6 Examples of thin films prepared using hydrothermalelectrochemical technique. (Ba, Sr)TiO 3 deposited on Si/SiO 2 /Ti/Au substrate SEM images of BST thin film EDX spectrum of BST thin film 6

7 Examples of thin films prepared using hydrothermalelectrochemical technique. Previous experience Hybrid organic-inorganic nanopowders based on hydroxyapatite and maleic copolymers deposited on TiAlNb alloy Potential Cyclic Voltammetry (100 mv/s) Chrono Amperometry ( mv) 7

8 Examples of thin films prepared using hydrothermalelectrochemical technique. Previous experience IN VIVO TESTS on Hydrothermal-electrochemical depositions Implant interface identification It can be observed the formation of new bone tissue in contact with fibrous tissue in exterior and with a mass of platelets on the implant surface Roxana Mioara Piticescu, Gabrielle Charlotte Chitanu Laura Madalina Popescu, Florin Miculescu, Ion Patrascu, Lucian Ciocan, unpublished 8

9 IN VIVO TESTS on hydrothermal-electrochemical depositions Morphostructural aspects in the interface area of the implant with biologic tissue in stage of structural and compositional remodeling 9

10 Examples of thin films prepared using hydrothermalelectrochemical technique. Previous experience IN VIVO TESTS on Hydrothermal-electrochemical depositions 3D deposition of hybrid organic-inorganic nanopowder on cylindrical Ti alloy Insertion of implant in rabbit bone. Macroscopic image of a cylindrical implant made of hybrid organic-inorganic nanopowders deposited on TiAlNb alloy, inserted in rabbit s bone. 1

11 Expertise gained in the frame of national projects (Program Nucleu PN Obtinerea de filme nanostructurate multifunctionale hibride prin procese de depunere fizica pentru aplicatii in domeniul biosenzorilor. Studiul proceselor fizico-chimice la interfata and CEEX, ctr. 46/2005 Integrated technological research network on advanced biocompatible structures for dental implants, RETE-β- DENT will be used in International Project H2020-MSCA-RISE- 2014, Grant no , Development of a non-invasive breath test for early diagnosis of tropical diseases, Acronym TROPSENSE, to obtain biosensors with potential use as electronic nose for tropical diseases. 11

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