Elektrohemijska i površinska karakterizacija trokomponentnih legura sistema Ag-Cu-Zn u blisko neutralnim hloridnim rastvorima
Electrochemical and surface characterization of ternary alloys of the system Ag-Cu-Zn in near neutral chloride solutions.
Doktorand
Dimitrijević, Stevan P.Mentor
Vujasinović-Rajčić, MirjanaČlanovi komisije
Kamberović, ŽeljkoGrekulović, Vesna
Stević, Zoran
Metapodaci
Prikaz svih podataka o disertacijiSažetak
Predmet istraživanja disertacije bile su legure sistema Ag-Cu-Zn sličnog sastava faza u
širokom opsegu sadržaja srebra. Metali za sve ispitivane legure dobijeni su reciklažom
elektronskog otpada. Nakon dobijanja dvostrukim topljenjem i homogenizacionog
žarenja u trajanju od 24h u atmosferi azota izvršena je površinska i elektrohemijska
karakterizacija ovih legura. Kao legure za uporednu analizu korišene su legure sistema
Ag-Zn i Cu-Zn, sastava sličnog fazama ispitivanih legura i legura Ag40Cu30Zn30 čiji
se fazni sastav značajno razlikuje od preostale tri trokomponentne legure istog sistema.
Termodinamička analiza Ag-Cu-Zn sistema izvršena je korišćenjem faznih dijagrama i
Pandat softvera. Za površinsku karakterizaciju homogenizovanih legura korišćena je
skenirajuća elektronska mikroskopija sa rentgenskom analizom (SEM/EDS) i
rentgenskom difrakcijom (XRD).
Elektrohemijsko ponašanje legura sistema Ag-Cu-Zn ispitivano je u deaerisanim i
prirodno aerisanim neutralnim rastvorima... NaCl koncentracije 3,5% (masenih),
sintetičkoj morskoj vodi, prirodnim filtriranim morskim vodama i boratnom puferu
(pH=8.1) sa (masenih) 3,5% NaCl, korišćenjem potenciodinamičkih merenja, linearne
polarizacije, ciklične voltametrije i potenciostatskih merenja.
Anodni film formiran na ispitivanim legurama hronoampermetrijski na 0,0 V i +0,25 V
(vs. ZKE) je ispitivan: rentgenskom difrakcijom, FE SEM/EDS metodom, Raman
spektroskopijom i MALDI masenom spektrometrijom.
Utvrđen je isti mehanizam korozije prilikom anodne polarizacije za sve legure u svim
hloridnim rastvorima, osim u puferisanom rastvoru NaCl. Naročito je slično ponašanje
legura Ag43Cu37Zn20 i Ag25Cu52,5Zn22,5. Legura sa 25% (mas.) srebra ima sličnu
otpornost na koroziju u 3,5% rastvoru NaCl kao legura sa 40% (mas.) srebra, što je
nedvosmisleno uticaj faznog sastava. Pri sličnom faznom sastavu legura koroziona
otpornost raste sa većim udelom srebra (faze bogate srebrom). Sve ispitivane legure
sistema Ag-Cu-Zn nemaju pasivnu oblast u svim rastvorima osim puferskog, gde se
javlja pseudo-pasivna oblast na polarizacionim krivama...
Alloys of the Ag-Cu-Zn system with wide range of silver content, selected to have similar
phase compositions, were the subject of the research. Metals for all examined alloys are
obtained by recycling of electronic waste. After obtaining alloys by double melting and
homogenization annealing for 24 h under nitrogen, surface and electrochemical
characterization of these alloys were performed. For comparative analysis, binary alloys
of Ag-Zn and Cu-Zn systems were used. They had similar composition as the phases of
the examined alloys. For the same purposes the Ag40Cu30Zn30 alloy with different
phase composition than three other alloys of the same system was used.
Thermodynamic analysis of the Ag-Cu-Zn system was performed using phase diagrams
and Pandat software. Surface characterization of the homogenizated alloys was
performed by Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS) and
X-diffraction (XRD).
Electrochemical behavior of the alloys of the Ag-Cu-Zn sy...stem in deaerated and
naturally aerated neutral 3.5 wt.% NaCl solution, synthetic seawater, natural filtered
seawaters and borate buffer (pH=8.1) with 3,5% NaCl has been investigated using the
potentiodynamic measurements, linear polarization, cyclic voltammetry and
potentiostatic measurements.
The anodic layer formed on examined alloys by chronoamperometry at 0.0 and +0.25 V
(vs. SCE) has been characterized by X-ray diffraction, FE SEM/EDS, Raman
spectroscopy and MALDI mass spectrometry.
The same mechanism of corrosion under anodic polarization was found for all alloys in
all chloride solutions except buffered 3.5% NaCl solution. The behavior of alloys
Ag43Cu37Zn20 and Ag25Cu52.5Zn22.5 is particularly similar. The alloy with 25 wt. %
content of silver has similar corrosion resistance in 3.5% NaCl solution as the alloy with
40 wt. % silver, which is clearly the consequence of phase composition. For a similar
phase composition of alloy, corrosion resistance increases with higher content of silver
(Ag-rich phase). All investigated alloys of the Ag-Cu-Zn system have no passive area in
all solutions, except in buffered solution, where a pseudo-passive area appears on
polarization curves.
Copper rich phase (Cu) is critical for corrosion resistance of alloys. Preferentially
dissolution of this phase is determined by polarization curves analysis, chemical...
Fakultet:
Универзитет у Београду, Технички факултет, БорDatum odbrane:
23-10-2015Projekti:
- Inovativna sinergija nus-produkata, minimizacije otpada i čistije proizvodnje u metalurgiji (RS-MESTD-Technological Development (TD or TR)-34033)