Hydrothermal-electrochemical processes. Techniques for functional ...

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

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11 September 2015, Bucharest

Hydrothermal – electrochemical methodDefinition

• Hydrothermal synthesis refers to any heterogeneous reaction in the presence of aqueous solvents or mineralizers underhigh pressure – high temperature (HPHT) conditions to dissolve and recrystallize (recover) materials that are relativelyinsoluble under ordinary conditions. Also, hydrothermal synthesis was defined as the heterogeneous reactions in aqueousmedia, 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, 2nd Ed., Elsevier, 2013].

• Hydrothermal-electrochemical technique combines hydrothermal process with electrochemical method and consists inelectrodeposition of highly crystalline thin films on metallic substrate (working electrode), directly from nanostructuredproducts of hydrothermal reaction. It is particularly important in the case of crystalline oxide products which can notprecipitate out of solution in the absence of an applied electric potential. This method refers to the reaction between speciesincluded in the electrolytic solution and the substrate being used as an electrode of the electrolytic cell under hydrothermalconditions [K. Byrappa, M. Yoshimura, Handbook of Hydrothermal Technology, 2nd 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.

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Schematic drawing of hydrothermal-electrochemical technique

Figure 1. Hydrothermal – electrochemical system. 1. colloidalsolutions; 2. Cortest autoclave (300°C, 250 atm); 3. autoclaveinsulation; 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. referenceelectrode, RE (Ag/AgCl); 10. pressure equalizer tap; 11. securityvalve; 12. manometer; 13. potentiostat / galvanostat PGZ 100; 14.booster HVB 100; 15. computer, software VoltaMaster 4; 16.programmer PID.

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Technological flow working principle mode


Examples of thin films prepared using hydrothermal-electrochemical technique.

(Ba, Sr)TiO3 deposited on Si/SiO2/Ti/Au substrate

Potential Cyclic Voltammetry (100 mV/s) Chrono Amperometry (-2000 – 2000 mV)

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Examples of thin films prepared using hydrothermal-electrochemical technique.

(Ba, Sr)TiO3 deposited on Si/SiO2/Ti/Au substrate

SEM images of BST thin film

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EDX spectrum of BST thin film

Examples of thin films prepared using hydrothermal-electrochemical technique. Previous experience

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Potential Cyclic Voltammetry (100 mV/s) Chrono Amperometry (1000 – 1500 mV)

Hybrid organic-inorganic nanopowders based on hydroxyapatite and maleic copolymers deposited on TiAlNb alloy


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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

IN VIVO TESTS on Hydrothermal-electrochemical depositions



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IN VIVO TESTS on hydrothermal-electrochemical depositions

Morphostructural aspects in the interface area of the implant withbiologic tissue in stage of structural and compositional remodeling


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IN VIVO TESTS on Hydrothermal-electrochemical depositions

Macroscopic image of a cylindricalimplant made of hybrid organic-inorganicnanopowders deposited on TiAlNb alloy,inserted in rabbit’s bone.

Insertion of implant in rabbit bone.

3D deposition of hybrid organic-inorganic nano-powder on cylindrical Ti alloy


• Expertise gained in the frame of national projects (Program NucleuPN “Obtinerea de filme nanostructurate multifunctionale hibrideprin procese de depunere fizica pentru aplicatii in domeniulbiosenzorilor. Studiul proceselor fizico-chimice la interfata” andCEEX, ctr. 46/2005 – “Integrated technological research network onadvanced biocompatible structures for dental implants, RETE-β-DENT” will be used in International Project H2020-MSCA-RISE-2014, Grant no.645758, “Development of a non-invasive breath testfor early diagnosis of tropical diseases”, Acronym TROPSENSE, toobtain biosensors with potential use as “electronic nose” for tropicaldiseases.

11 September 2015, Bucharest 11

11 September 2015, Bucharest 12

Hydrothermal-electrochemical processes. Techniques for functional ...

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