9 research outputs found
Formation of Oxide Phases in the System Fe203-Sm203
Formation of oxide phases in the system Fe2O3-Sm2O3 was investigated. The samples wore prepared by the solid state reactions et two molar ratios of Fe203 and Sm203
FT-IR and Mossbauer Study of Corrosion of Steel in Tap and Mineral Water
The influence of carbonates on the process of corrosion of steel in
aqueous media has been studied. The corrosion of steel in tap
water and mineral water of three different chemical compositions (all
for human use) was monitored for up to 6 months. Rust samples were
analyzed using Fourier transform infrared (FT-IR) spectroscopy and
57 Fe Mossbauer spectroscopy. Some selected samples were also analyzed by X-ray powder diffraction (XRD).It was shown that the concentration of carbonates plays an important role in the corrosion of steel in aqueous media, both during short (days), and long times
(months) of corrosion. For short times of corrosion in the presence of
a high content of carbonates, the rust was found amorphous for XRD.
It was proved that "\u27(-FeOOHwas absent in amorphous rust. The possible presence of ferrihydrite in this amorphous fraction is discussed taking into account the FT-IR and Mossbauer spectroscopic results. At a very high concentration of carbonates, after 6 month of corrosion,\u27(-FeOOHwas not found in the rust. Formation of a-FeOOH and Fe304 in corrosion products was also monitored. It was suggested
that, in the very early stages of corrosion, carbonates can be structurally incorporated in the rust in the form of hydroxycarbonates,
while in the later stages, they can modify the phase transformation
by the mechanism of specific adsorption
Formation of Rust During the Corrosion of Steel in Water and (NH4)2S04 Solutions. Part II
Chemical and structural properties of the rust formed by corrosion of steel in water and (NH4)2S04 solutions at 20 Ā°C for time periods up to 6 months were investigated by X-ray dittraction, Fourier transform IR spectroscopy and 67Fe Mossbauer spectroscopy
Stvaranje hrÄe tijekom korozije Äelika u vodi i otopinama (NH4)2S04. II.
Chemical and structural properties of the rust formed by corrosion of steel in water and (NH4)2S04 solutions at 20 Ā°C for time periods up to 6 months were investigated by X-ray dittraction, Fourier transform IR spectroscopy and 67Fe Mossbauer spectroscopy.Kemijska i strukturna svojstva hrÄe, stvorene korozijom Äelika u vodi i otopinama (NH4)2S04 pri 20 Ā°C u vremenskom periodu do 6 mjeseci, istraživana su difrakcijom X-zraka, FT-IR spektroskopijom i 57Fe Mossbauerovom spektroskopijom. U uzorcima hrÄe detektirane su tri oksidne faze: lepidokrokit, magnetit i getit. Raspodjela tih faza u uzorcima hrde ovisila je o vremenu korozije i o koncentraciji (NH4)2SO4. 57Fe Mossbauerova spektroskopija pokazala je nestehiometrijski karakter magnetita (Fe3-x04). Magnetit nije opažen u hrÄi koja je stvorena u otopini 2M (NH4)2S04. FT-IR spektroskopija pokazala se posebno pogodnom za odreÄivanje malih koliÄina getita i lepidokrokita u hrÄi. Snažan utjecaj koncentracije (NH4)2S04 na fazni sastav hrÄe objaÅ”njen je kumulativnim efektom iona NH4+ i SO2- agresivnih u korozijskom smislu
Stvaranje hrÄe tijekom korozije Äelika u vodi i otopinama (NH4)2S04. II.
Chemical and structural properties of the rust formed by corrosion of steel in water and (NH4)2S04 solutions at 20 Ā°C for time periods up to 6 months were investigated by X-ray dittraction, Fourier transform IR spectroscopy and 67Fe Mossbauer spectroscopy.Kemijska i strukturna svojstva hrÄe, stvorene korozijom Äelika u vodi i otopinama (NH4)2S04 pri 20 Ā°C u vremenskom periodu do 6 mjeseci, istraživana su difrakcijom X-zraka, FT-IR spektroskopijom i 57Fe Mossbauerovom spektroskopijom. U uzorcima hrÄe detektirane su tri oksidne faze: lepidokrokit, magnetit i getit. Raspodjela tih faza u uzorcima hrde ovisila je o vremenu korozije i o koncentraciji (NH4)2SO4. 57Fe Mossbauerova spektroskopija pokazala je nestehiometrijski karakter magnetita (Fe3-x04). Magnetit nije opažen u hrÄi koja je stvorena u otopini 2M (NH4)2S04. FT-IR spektroskopija pokazala se posebno pogodnom za odreÄivanje malih koliÄina getita i lepidokrokita u hrÄi. Snažan utjecaj koncentracije (NH4)2S04 na fazni sastav hrÄe objaÅ”njen je kumulativnim efektom iona NH4+ i SO2- agresivnih u korozijskom smislu
Formation of Oxide Phases in the System Fe203-Sm203
Formation of oxide phases in the system Fe2O3-Sm2O3 was investigated. The samples wore prepared by the solid state reactions et two molar ratios of Fe203 and Sm203
Formation of Rust During the Corrosion of Steel in Water and (NH4)2S04 Solutions. Part II
Chemical and structural properties of the rust formed by corrosion of steel in water and (NH4)2S04 solutions at 20 Ā°C for time periods up to 6 months were investigated by X-ray dittraction, Fourier transform IR spectroscopy and 67Fe Mossbauer spectroscopy
Formation and Characterization of NiFe2O4
Synthesis of nickel ferrite, NiFe204, was performed applying the
thermal treatment of the corresponding mixed metal hydroxides or
the solid state reaction between NiO and a-Fe203. The samples
were studied by X-ray diffraction, Fourier transform IR spectroscopy
and 57Fe MÄssbauer spectroscopy. Ball-milling of NiFe204
caused a decrease of hyperfine magnetic fields corresponding to
Fe3+ ions in tetrahedral and octahedral sites, an increase of the
Mossbauer spectral line widths, as well as a slight increase of isomer
shifts. It was supposed that the ball-milling of NiFe204 had
more influence on the degree of inversion than on other structural
properties of the spinel. It was found that the heating temperature,
and not the heating time, had the ultimate effect on NiFe204 microstructure. Samples heated up to 500 Ā°C showed a pronounced
size-correlated diffraction line broadening, corresponding to the coherent domain size of about 13 nm, and rather small crystalline
disorder. Samples heated at temperature s above "" 1000 Ā°C had
much larger crystallites, exhibiting very small disorder
Formation and Characterization of NiFe2O4
Synthesis of nickel ferrite, NiFe204, was performed applying the
thermal treatment of the corresponding mixed metal hydroxides or
the solid state reaction between NiO and a-Fe203. The samples
were studied by X-ray diffraction, Fourier transform IR spectroscopy
and 57Fe MÄssbauer spectroscopy. Ball-milling of NiFe204
caused a decrease of hyperfine magnetic fields corresponding to
Fe3+ ions in tetrahedral and octahedral sites, an increase of the
Mossbauer spectral line widths, as well as a slight increase of isomer
shifts. It was supposed that the ball-milling of NiFe204 had
more influence on the degree of inversion than on other structural
properties of the spinel. It was found that the heating temperature,
and not the heating time, had the ultimate effect on NiFe204 microstructure. Samples heated up to 500 Ā°C showed a pronounced
size-correlated diffraction line broadening, corresponding to the coherent domain size of about 13 nm, and rather small crystalline
disorder. Samples heated at temperature s above "" 1000 Ā°C had
much larger crystallites, exhibiting very small disorder