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1.
P. Kavouras Th. Kehagias K. Chrissafis Ph. Komninou Th. Karakostas 《Journal of Thermal Analysis and Calorimetry》2006,86(3):715-719
Three batch compositions of pure oxides (SiO2,
Fe2O3, PbO, Na2O)
with equivalent SiO2, Fe2O3
and PbO contents and a gradually increased Na2O content
were vitrified through heating in a high temperature electric furnace and
subsequent quenching. The resulting vitreous products were thermally treated
in order to study the devitrification behaviour, under conditions designated
from differential thermal analysis experiments. Depending on the Na2O
content, crystal phase separation gave rise to the growth of acmite and hematite
or maghemite. A uniformly phase separated glass-ceramic material, with crystallites
of similar size and population density, was produced from devitrification
of the vitreous product with the higher Na2O content. 相似文献
2.
K. Chrissafis K. M. Paraskevopoulos C. Manolikas 《Journal of Thermal Analysis and Calorimetry》2006,84(1):195-199
The
thermal effect accompanying the transition of Cu2–xSe
into a superionic conduction state was studied by non-isothermal measurements,
at different heating and cooling rates (β=1, 2.5, 5, 10 and 20°C
min–1). During heating the peak temperature
(Tp) remains almost
stable for all values of β, (136.8±0.4°C for Cu2Se
and 133.0±0.3°C for Cu1.99Se). A gradual
shift of the initiation of the transformation towards lower temperatures is
observed, as the heating rate increases. During cooling there is a significant
shift in the position of the peak maximum (Tp)
towards lower temperatures with the increase of the cooling rate. A small
hysteresis is observed, which increases with the increase of the cooling rate, β.
The mean value of transformation enthalpy was found to be 30.3±0.8
J g–1 for Cu2Se and
28.9±0.9 J g–1 for Cu1.99Se.
The transformation can be described kinetically by the model f(ǯ)=(1–ǯ)n(1+kcatX), with activation energy E=175 kJ mol–1,
exponent value n equal to 0.2, logA=20 and log(kcat)=
0.5. 相似文献
3.
G. Vourlias N. Pistofidis D. Chaliambalias K. Chrissafis El. Pavlidou G. Stergioudis 《Journal of Thermal Analysis and Calorimetry》2007,87(2):401-409
Zinc coatings on ferrous substrates are possible to be applied with
thermal spraying. In the present work the corrosion behavior of zinc thermal
sprayed coatings deposited on low carbon steel St-37 was examined in a simulated
marine atmosphere (salt spray chamber-SSC) and in a dry atmosphere at elevated
temperature (400°C). The corrosion progress was examined by means of optical
microscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric
analysis. From this investigation it was deduced that in the SSC the coating
is uniformly corroded, while the main corrosion products are hydrated zinc
oxides and chlorides. By contrast at 400°C only a thin, compact and continuous
film of ZnO is formed on top of the coating, which remains adherent to the
ferrous substrate. 相似文献
4.
M. Anastasiou Th. Hasapis T. Zorba E. Pavlidou K. Chrissafis K. M. Paraskevopoulos 《Journal of Thermal Analysis and Calorimetry》2006,84(1):27-32
Historic
plasters from wall paintings of Byzantine and post-Byzantine churches situated
in the Balkan region were studied. All wall paintings were made with fresco
technique and are dated from IX - XVI century. Plaster samples were followed
from room temperature to 1000°C by Thermogravimetric (TG) and Differential
Thermal Analysis (DTA), and one or two significant temperature regions, corresponding
to thermal decomposition mechanisms were observed. The analysis of the plaster
samples and the composition characterization was carried out using also, Fourier
Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM).
Although the main components are calcite and quartz (from sand) in different
proportions, there are differences between them such as the presence of gypsum
being either as a constituent element or due to environmental pollution. The
results are examined comparatively taking into account the creation time and
place of the paintings. 相似文献
5.
P. Aslanidis K. Chrissafis M. Lalia-Kantouri 《Journal of Thermal Analysis and Calorimetry》2011,103(3):797-803
Copper (I) halide complexes formulated as [(L)2Cu(μ2-L)2Cu(L)2]2+ 2Χ−, (X = Cl, Br and L = pyridine-2-thione (py2SH) or 4,6-dimethylpyrimidine-2-thione (dmpymtH)) were prepared, and their photoluminescence
and thermal properties were investigated. The complexes are strongly emissive in the solid state, with the emissions being
dominated by large Stokes shifts (>200 nm), which are depending on both the heterocyclic thione and the nature of the halogen.
These emissions can be assigned to MLCT with some mixing of the halide-to-ligand (XL) CT characters. Simultaneous TG/DTG–DTA
technique was used for two complexes with the dmpymtH ligand to determine their thermal degradation, which was found to be
very complicated. In inert atmosphere the residues at 1,000 °C (verified with PXRD) were mainly Cu2S, while at 1,300 °C a mixture of Cu2S and Cu. In oxygen atmosphere the residues were CuO. 相似文献
6.
P. Aslanidis V. Gaki K. Chrissafis M. Lalia-Kantouri 《Journal of Thermal Analysis and Calorimetry》2011,103(2):525-531
Copper(I) halide complexes formulated as [(L)CuX(μ2-L)2CuX(L)] (X = Cl, Br and L = pyridine-2-thione (py2SH), or 4,6-dimethylpyrimidine-2-thione (dmpymtH)) were prepared, and their
photoluminescence and thermal properties were investigated. The complexes are strongly emissive in the solid state, with the
emissions being dominated by large Stokes shifts (>200 nm), which are depending on both the heterocyclic thione and the nature
of the halogen. These emissions can be assigned to MLCT with some mixing of the halide-to-ligand (XL) CT characters. Simultaneous
TG/DTG–DTA technique, coupled with MS for the analysis of the gaseous decomposition products, was used for two complexes with
the dmpymtH ligand to determine their thermal degradation, which was found to be very complicated. In inert atmosphere the
residues at 1,000 °C (verified with PXRD) were a mixture of Cu2S and CuX, while at 1,300 °C a mixture of Cu2S and Cu. In oxygen atmosphere the residues were CuO. 相似文献
7.
8.
9.
Bi2Se3 and Bi2Te3 are layered semiconductors n-type and p-type, respectively, which belong to the family of thermoelectric materials. In this
work we examine the insertion of Cu in Bi2Te3 and Bi2Se3 single crystals through an intercalation reaction. The inserted Cu acting as donor enhances the n-type character of Bi2Se3 while changing the native p-type character of Bi2Te3 to n-type. The spatial distribution of the intercalated species was monitoring by X-ray microanalysis and microscopic IR
reflectivity measurements.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997 相似文献
10.
Dagounaki C. Chrissafis K. Kassoli-Fournaraki A. Tsirambides A. Sikalidis C. Paraskevopoulos K. M. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):295-306
The curing of a thermoreactive alkyd-melamine-formaldehyde resin system was investigated by rheologycal, TG and TMA-analysis,
in order to construct the time-temperature-transformation diagram. The points of the gelation curve were determined by measuring
the increase in viscosity during isothermal curing at different temperatures. A power-function could be fitted to the gelation
curve, which is suitable to estimate gelation at any curing conditions, as well as to establish storage conditions. The reaction
in the resin matrix was followed by monitoring the loss of mass during isothermal curing at different temperatures. The final
section of the resulted iso-curing temperature (iso-T
cure) diagrams could be fitted with logarithmic functions, which may be used for estimating the conditions needed to a given,
desirable mass loss, i.e. conversion. The steepness of the curves increases with temperature suggesting the forthcoming of
degradation during cure with increasing temperature. From these data the iso-mass loss curves of the TTT-diagram were constructed.
For determining the iso-Tg curves of the TTT-diagram isothermal curing was carried out in a drying oven at different temperatures,
followed by TMA measurements. The iso-Tcure diagrams served to determine T
g
¥, and to construct the iso-T
g curves of the TTT diagram. Vitrification curve is far beyond conditions of storage, curing and degradation, meaning that
the resin matrix is in rubbery physical state before, during and after the cure. Curing conditions resulting degradation can
also be estimated from the TTT-diagram.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献