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1.
In this study, abrasive wear behaviour of bio-active glass ceramic materials produced with two different processes is studied.
Hot pressing process and conventional casting and controlled crystallization process were used to produce bio-active ceramics.
Fracture toughness of studied material was calculated by fracture toughness equations using experimental hardness results
of the bio-active glass ceramic material. Two fracture toughness equations in the literature were used to identify the wear
behaviour of studied ceramics. Wear resistance results that identified with both of the equations were similar. The results
showed that the abrasive wear resistance of the bio-active glass ceramics produced with hot pressing process was found to
be higher than that of the ceramics produced by conventional casting and controlled crystallization process. 相似文献
2.
B. Eraiah 《Bulletin of Materials Science》2006,29(4):375-378
Glasses with the composition, (Sm2
O
3)
x
(ZnO)(40-x)(TeO
2)(60), were prepared by conventional melt quenching method. The density, molar volume, and optical energy band gap of these glasses
have been measured. The refractive index, molar refraction and polarizability of oxide ion have been calculated by using Lorentz-Lorentz
relations. Optical absorption spectra of these glasses were recorded in the range 300–700 nm at room temperature. The oxide
ion polarizabilities deduced from two different quantities, viz. refractive index and optical energy band gap, agree well
compared with other glasses. The nonlinear variation of the above optical parameters with respect to samarium dopant has been
explained. 相似文献
3.
Pika Jha Saroj L. Samal Kandalam V. Ramanujachary Samuel E. Lofland Ashok K. Ganguli 《Bulletin of Materials Science》2005,28(6):571-577
Oxides of the type (La2/5Ba2/5Ca1/5)(Mn(2/5)-x Ni x Ti3/5)O3 (0 ≤ x ≤ 0.4) have been synthesized by the ceramic route. All the above oxides have been found to crystallize in the cubic perovskite structure. Rietveld refinement of the Ni-based oxide, (La2/5Ba2/5Ca1/5)(Ni2/5Ti3/5)O3 gave rise to a composition (La0.44Ba0.38Ca0.18) (Ni0.42Ti0.58)O2.85(6) and the refined lattice parameter obtained was 3.9411(2) Å (space group Pm3m;R(F2) = 0.026,R p = 0.074,wR p = 0.087). A shift from antiferromagnetic to paramagnetic behaviour is observed with increase in nickel concentration, the Mn-rich phases showing antiferromagnetism around 5 K. There is a systematic decrease in the dielectric constant, ε and loss tangent with increase in Ni concentration (from ε = 592 forx = 0 to ε = 78 forx = 0.4). 相似文献
4.
N. Srinivasa Rao M. Purnima Shashidhar Bale K. Siva Kumar Syed Rahman 《Bulletin of Materials Science》2006,29(4):365-370
Pure and copper doped glasses with composition,x
Li
2
O-(40-x)Na
2
O-50B
2
O
3-10Bi
2
O
3,have been prepared over the range 0 ≤
x ≤ 40. The electron paramagnetic resonance (EPR) spectra of Cu2+ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated.
The molecular bonding coefficients, α2 and β2, have been calculated by recording the optical absorption spectra in the wavelength range 200–1200 nm. It has been observed
that the site symmetry around Cu2+ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows
non-linear behaviour. The IR studies show that the glassy system contains BO3 and BO4 units in the disordered manner. 相似文献
5.
N. Srinivasa Rao Shashidhar Bale M. Purnima K. Siva Kumar Syed Rahman 《Bulletin of Materials Science》2005,28(6):589-592
The local structure around Cu2+ ion has been examined by means of electron spin resonance and optical absorption measurements in xLi2O-(40-x)Na2O-50B2O3-10As2O3 glasses. The site symmetry around Cu2+ ions is tetragonally distorted octahedral. The ground state of Cu2+ isd
x
2−y
2.The glass exhibited broad absorption band near infrared region and small absorption band around 548 nm, which was assigned
to the
2B1g →2Eg
transition. 相似文献
6.
S. R. Murthy 《Bulletin of Materials Science》2001,24(6):611-616
Polycrystalline NiZn ferrites with different grain sizes (1.2 (Am to 10.2 (Am) were prepared by the usual ceramic method.
The magnetic properties were measured at room temperature. The ultrasonic velocity and attenuation were measured on Ni-Zn
ferrite by using the pulse transmission method at 1 MHz, in the temperature range 300–600 K. The velocity was found to be
slightly sample dependent at room temperature and decreased with increasing temperature, except near the Curie temperature,
T
c
,where a small anomaly was observed. The longitudinal attenuation (α
1
)at room temperature was found to be more sample dependent. The temperature variation of ultrasonic longitudinal attenuation
exhibited a broad maximum around 400 K and a sharp maximum just below Curie temperature (
T
c
).The above observations were carried out in the demagnetized state. The application of a 380 mT magnetic field allowed us to
reach the saturated state of the sample at all the measuring temperatures. The anomaly observed in the thermal variation of
velocities (longitudinal and transverse) and attenuation has been qualitatively explained with the help of the temperature
variation of the magneto-crystalline anisotropy constant. 相似文献
7.
N. K. Lokanath M. A. Sridhar J. ShashidharA Prasad G. S. Gopalakrishna K. G. Ashamanjari 《Bulletin of Materials Science》2000,23(3):175-178
Na2MnP2O7 crystals were synthesized by hydrothermal technique. Crystals obtained are in the form of single crystals of rhombohedral morphology with lattice parameters as follows: triclinic, P 1, π = 0-71069 Å, a = 6.657(3) Å, b = 6.714(6) Å, c = 6.518(4) Å, α = 112.31(6)°, β = 92.14(4)°, γ = 83.89(5)°, V = 268.0(3) Å3, Z = 2, ρcal = 2, 3.121 g/cm3, μ = 3.121 mm-1, F000 = 244, goodness-of-fit on F = 1.348, final R indices with [I > 3σ(I)]R = 0051 and ωR = 0.065. 相似文献
8.
A. Subramania N. Angayarkanni A. R. Sathiya Priya R. Gangadharan T. Vasudevan 《Bulletin of Materials Science》2005,28(7):663-667
Abstract. Cubic spinels of composition, LiMgyMn2-yO4, with y = 0.0, 0.05, 0.1, 0.15 and 0.2, were synthesized by a modified Pechini process using polyethylene glycol and citric
acid. The phase formation and/or crystallization of the precursors were studied by thermal analysis. Products were characterized
by X-ray diffraction and SEM analysis. Coin cells were fabricated with lithium as the anode and LiMgyMn2-yO4 as the cathode in an electrolyte of 1 M LiPF6 in a 1: 1 (v/v) mixture of EC and DEC. The charge-discharge studies were performed and the results were compared with materials
prepared by a solid state thermal method. 相似文献
9.
The preparation of an organic-inorganic hybrid material by solid state intercalation of 2-mercaptopyridine (2Mpy) into Na-, Co(II)- and Al(III)-montmorillonite has been studied using a variety of techniques. The extension ofd 001from XRD proves that the intercalation of 2-mercaptopyridine into Na-, Co(II)- and Al(III)-mont occurs at ambient temperature in 5 mn. When the intercalated samples were heated at different temperatures, we found that the d001 gave different values. For instance, for intercalated Al(III)- and Co(II)-, d001 remained unchanged for a temperature under 500°C. However, for intercalated Na-mont, it shifted to 14 Å for a temperature of 300° C, the washing of different samples with a methanol solution shifted thed 001of intercalated Na-mont to 14 Å. However, for intercalated Al(III) and Co(II), it did not change. This proves that in the case of Na-mont, the molecules of 2-mercaptopyridine interact with the clay through hydrogen bindings and physical interactions. However, for Al(III) and Co(II), it forms coordination linking and physical interaction.13C NMR and FTIR spectroscopy have been employed for the characterization of the intercalation compounds. Tautomeric equilibrium between thiol and thione species of 2-mercaptopyridine must be taken into account to explain the arrangement of molecular aggregates and their particular orientation in the interlayer space. The isotherm of adsorption-desorption of nitrogen and topographic AFM images prove that intercalation of 2Mpy is accompanied by a total blockage of clay porosity and an increase in roughness. 相似文献
10.
A gel was formed when a aqueous solution of BaCl2, NbF5 and citric acid in stoichiometric ratio is heated on a water bath. This gel on decomposition at 600°C yielded the nano crystallites
of BaNb2O6, as confirmed by X-ray diffraction study (XRD). This is a much lower temperature as compared to that prepared by traditional
solid state method (1000°C) as reported for the formation of BaNb2O6. Transmission electron microscopic (TEM) investigations revealed that the average particle size is 50 nm for the calcined
powders. The room temperature dielectric constant at 1 kHz is found to be 1000. The ferroelectric hysteresis loop parameters
of these samples were also studied. 相似文献
11.
12.
K. L. Ramakumar 《Bulletin of Materials Science》2005,28(4):331-337
Available analytical literature reveals that it is possible to identify a lot of procedures to carry out any determination
using a plethora of analytical techniques. The fundamental analytical requirements for realizing the desired and acceptable
information from a chemical analysis are representative nature of the sample, precision, accuracy, selectivity and sensitivity.
These decide, to a larger extent, the selection of the most appropriate methodology in order to obtain chemical information
from a system. A number of analytical methodologies are being used in the author’s laboratory for carrying out trace elemental
analysis as a part of chemical quality control. Quite a good number of analytical challenges with specific reference to the
characterization of high purity materials of relevance to nuclear technology were addressed and methodologies were developed
for trace elemental analysis of both metallic and non-metallic constituents. A brief review of these analytical challenges
and the analytical methodologies developed and also the future needs of analytical chemist are presented in this paper. 相似文献
13.
J. Shakhapure H. Vijayanand S. Basavaraja V. Hiremath A. Venkataraman 《Bulletin of Materials Science》2005,28(7):713-718
Solid adsorbents have shown great promise for control of particulate and non-particulate matter and as gas sensing devices
in recent times. In the present study, adsorption of environmental toxic pollutant such as lead ions on solid adsorbents viz.
α-Fe2O3 and fly ash, are reported. Considerable adsorption was observed on fly ash when compared to α-Fe2O3 surface. These studies are characterized by employing solid state and solution studies. 相似文献
14.
The metallic glass samples of Fe
67Co18B14Si1 (2605CO), prepared by the melt spinning technique were procured from the Allied Corporation. The kinetics of crystallization
of this multicomponent glassy alloy is studied using differential scanning calorimetry (DSC). The crystallization data have
been examined in terms of modified Kissinger and Matusita equations for the nonisothermal crystallization. The results show
enhanced bulk nucleation in general. At high heating rates added to it is surface induced abnormal grain growth resulting
in fractal dimensionality.
5th IUMRS ICA98, October 1998, Bangalore. 相似文献
15.
An effective interaction potential (EIOP) is developed to invoke the pressure induced phase transition from zinc blende (B3) to rocksalt (B1) structure and anharmonic properties in ZnX (X = Se, S, Te) semiconductors. The effective interaction potential incorporates
the long range Coulomb interaction, van der Waals interaction and short-range repulsive interaction up to second neighbour
ions within the Hafemeister and Flygare approach as well as the charge transfer effects caused by the electron-shell deformation
of the overlapping ions. The van der Waals coefficients are computed by the Slater Kirkwood variation method as a first step.
Later on, we evaluate volume collapse, second order and third order elastic constants with pressure pointing to the systematic
trends in all compounds of zinc blende structure and their thermal properties such as force constant, Gruneisen parameter,
compressibility, Debye temperature etc. The vast volume discontinuity in pressure-volume (PV) phase diagram identifies the
structural phase transition from zinc blende (B3) to rock salt (B1) structure and is consistent with those revealed from earlier reports. 相似文献
16.
P. P. Singh 《Bulletin of Materials Science》2003,26(1):131-135
Using density-functional-based methods, we have studied the fully-relaxed, fulltronic structure of the newly discovered superconductor,
MgB
2, and BeB2, NaB2 and AlB2. Our results, described in terms of (i) total density of states (DOS) and (ii) the partial DOS around the Fermi energy, EF, clearly show the importance of B p-electrons for superconductivity. For BeB2 and NaB2, our results indicate qualitative similarities but significant quantitative differences in their electronic structure due
to differences in the number of valence electrons and the lattice constantsa andc.
We have also studied Mg
1-xMxB2 (M = Al, Li or Zn) alloys using coherent-potential to describe disorder, Gaspari-Gyorffy approach to evaluate electron-phonon
coupling, and Allen-Dynes equation to calculate the superconducting transition temperature, Tc. We find that in Mg1-xMxB2 alloys (i) the way Tc changes depends on the location of the added/modified k-resolved states on the Fermi surface and (ii)
the variation of Tc as a function of concentration is dictated by the Bp DOS. 相似文献
17.
Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of
semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons
of the tube screen the magnetization of the dopants: the coupling to the tube is usually antiferromagnetic (except for Cr). 相似文献
18.
P. T. Deshmukh D. K. Burghate V. S. Deogaonkar S. P. Yawale S. V. Pakade 《Bulletin of Materials Science》2003,26(6):639-642
The optical transmission and absorption spectra in UV- VIS were recorded in the wavelength range 350–800 nm for different
glass compositions in the system (CuO)
x
(PbO)
50−x(Bi2O3)50 (x = 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0). Absorption coefficient (α), optical energy gap (Eopt), refractive index (nD), optical dielectric constant (ε′∞), measure of extent of band tailing (ΔE), constant (β) and ratio of carrier concentration to the effective mass (N/m*) have
been reported. The effects of compositions of glasses on these parameters have been discussed. It has been indicated that
a small compositional modification of the glasses lead to an important change in all the optical properties including non-linear
behaviour. The optical parameters were found to be almost the same for different glasses in the same family. 相似文献
19.
Isothermal ac MH (magnetization-field) loops for varying field amplitudes were recorded at 77 K on YBa2(Cu1-xMnx)3O7-δ with x = 0, 0.010, 0.015, 0.020, 0.025, 0.035 and 0.050, YBa2(Cuo.o75Fe0.025)3O7-δ, YBa2(Cu0.075Ni0.025)3O7-δ and YBa2(Cu0.075Zn0.025)3O7-δ samples up to a maximum field amplitude of 80 Oe. Flat band susceptibility, ac losses and flux profiles were deduced from
the ac MH loops. The undoped sample exhibited a minimum weak link ac loss and the 5.0% doped sample showed maximum weak link
ac loss. Ni and Fe doped samples showed higher granular losses.J
cg estimated from the flux profiles decreases monotonically with increasing concentrations of Mn up to 2.5%. 相似文献
20.
The d.c. electrical conductivity of Na2O-ZnO-B2O3 glass system has been measured as a function of temperature in the range of 350–600°K. The conductivity data show that the
activation energy of Na+ ions is dependent on ZnO concentration. The results have been discussed in the light of the cluster model of glasses. 相似文献