Showing papers by "Wuhan University of Technology published in 1992"
TL;DR: In this article, the effects of different dopant species and combinations of dopants and the effect of microstructure are examined in terms of the properties of transition temperature, transition width, resistivity ratio, and transition hysteresis size.
Abstract: Doped V2O3 is examined to understand its useful properties as a positive temperature coefficient (PTC) material. The effects of different dopant species and combinations of dopant species and the effects of microstructure are examined in terms of the properties of transition temperature, transition width, resistivity ratio, and transition hysteresis size. In addition to the previously used dopants of Cr and Al, the dopants In, Al+Cr, Al+In, and Al+Ga are also found to be effective at producing a PTC phase transition. The combination of Al+In produced the best resistivity ratio for its transition temperature. Higher sintering temperatures are found to produce larger grains and a sharper transition. The sharper transition is interpreted as the combined effect of heterogeneous nucleation and self-catalysation within a single grain. The hysteresis decreases from over 100 K between the first cooling and the following heating to around 50 K for subsequent thermal cycles. This is most likely a result of the formation of microcracks which are observed in the ceramic. An additional five cycles, though, shows no measurable decrease in the hysteresis size indicating no further growth of the microcracks.
18 citations
TL;DR: In this paper, the dynamic behavior of straight elasto-plastic columns subjected to axial solid-fluid slamming compression is investigated experimentally and three critical conditions for each of the columns are observed from the experiments: plastic incipience, buckling and plastic collapse.
16 citations
TL;DR: PbBr 2 PbI 2 CuBr(Cl) KBr glasses have been synthesized in this paper, and the experimental results show that the effect of mixed ions can improve glass-forming ability.
Abstract: PbBr 2 PbI 2 CuBr(Cl) KBr glasses have been synthesized. Their chemical resistance is much better than that of ZnCl 2 -based and CdBr 2 (CdI 2 )-based glasses. The infrared cut-off wavelength of PbBr 2 PbI 2 CuBr KBr glasses is 18 μm. The glass formation was studied by infrared spectra analysis and differential thermal analysis. The experimental results show that the effect of mixed ions can improve glass-forming ability.
9 citations
TL;DR: In this article, some kinetics parameters of alumina during microwave sintering were studied and compared with that during conventional processing, and it was indicated that the microwave processing at higher temperatures for a shorter time was favorable for preparing high density and fine-grained alumina ceramics.
Abstract: Some kinetics parameters of alumina during microwave sintering were studied and compared with that during conventional sintering. The results demonstrated that the sintering rates for microwave processing were much greater than that for conventional processing, and the grain growth of alumina was rapid with prolonged time at high temperature in a microwave field. It was indicated that the microwave sintering at higher temperatures for a shorter time was favorable for preparing high density and fine-grained alumina ceramics.
8 citations
TL;DR: In this article, the influence of mixed-cation and mixed-anion effect on glass formation is discussed. And the results show that both mixedcation and mixing effects are beneficial to glass formation for dynamic reasons and the weak chemical bond introduced by the mixed anion effect may reduce glass formation of some strong systems.
Abstract: The influence of mixed-cation effect and mixed-anion effect on glass formation is discussed The results show that both mixed-cation and mixed-anion effects are beneficial to glass formation for dynamic reasons and the weak chemical bond introduced by the mixed-anion effect may reduce glass formation of some strong systems, such as ZrF 4 -based and AlF 3 -based glass However, for CdF 2 -based, MnF 2 -based and heavy halide glass, the weak glass formation is enhanced by the mixed-anion effect
8 citations
TL;DR: In this article, a continuum damage mechanics approach is used to develop a constitutive model for describing the characteristics of fiber-reinforced composite materials damaged by matrix cracking, where the matrix cracks are assumed to be an array of parallel cracks along fibers in the plies, and the average measurement of the damage effects by this special damage state on the composite materials is represented by a vectorial internal state variable (ISV).
6 citations
TL;DR: In this article, a novel element of a plate is presented, where the degrees of freedom of a corner node (not a midside node) can be different from that of the others.
4 citations
01 Jan 1992
TL;DR: In this paper, the geometric nonlinear forced flexural vibration of anisotropic composite material symmetrically laminated plates under the harmonic force was discussed and an analysis of the complete solution analysis process including computing examples was presented.
Abstract: In this paper, the author discusses the geometric nonlinear forced flexural vibration of anisotropic composite material symmetrically laminated plates under the harmonic force, makes an analysis of the complete solution analysis process including computing examples, obtains the illustrative amplitude-frequency relationships of the laminated plates with different ply-direction angles and under the load of different magnitude and especially analyzes the effect of the ply-direction angle of the symmetrically laminated plates on the amplitude-frequency relationships of nonlinear forced vibration of the plates
2 citations
01 Oct 1992-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the effects of 57Fe-implanted Al2O3 and post-implantation thermal annealing on surface properties and structure of an implanted layer have been studied by electric measurement.
Abstract: The effects of 57Fe-implanted Al2O3 and post-implantation thermal annealing on surface properties and structure of an implanted layer have been studied by electric measurement. X-ray photoelectron spectroscopy (XPS) and Mossbauer spectroscopy. It has been found that the resistivity of the implanted layer of polycrystalline alumina is greatly reduced and that relatively high doses and suitable annealing temperatures must be used to achieve modification of the electrical properties. XPS and Mossbauer spectroscopy measurements have shown that the implanted iron ions are in three charge states of Fe4+, Fe2+ and Fe0 for an as-implanted sample. After thermal annealing, the iron is present as Fe3+, Fe2+ and Fe0. Finally, the conductivity mechanisms are discussed briefly. The electrical conductivity for Fe-implanted polycrystalline alumina may be caused not only by mobile interstitials of aluminum and electronic defects but also by the implanted metallic elements themselves.
2 citations
TL;DR: In this paper, the structure of 3CaO · 3Al 2 O 3 · BaSO 4 was determined by computer programs based on the single-crystal structure of the compound as T 5 −123; a = b = c = 9.303 ± 0.002 A, α = β = γ = 90°, density 3.01 g cm −3.
2 citations
01 Sep 1992
TL;DR: In this paper, a vibrational assignment for the B11H−14 amine boranes is proposed based on the appearance of several bands on going from (C2H5)4NCl to (C 2H5,4NB11H14), and the Ni-P vibration frequencies are located at about 202 and 177 cm−1.
TL;DR: This method is based on the logical induction which is different from the traditional statistic method and is a practical way to analyze macroeconomic systems.
01 Jan 1992
TL;DR: In this article, the effects of stiffness ration as well as scarf angles on the adhesive stresses are discussed by examples and some conclusions have been obtained from this work. And the governing differential equations are given.
Abstract: Composites scarf joints with different elastic moduli and thickness between adherends are studied and the governing differential equations are given in this paper. Adherends and adhesive stress distributions of scarf joints between stiffness imbalanced composite materials are calculated and analysed by finite difference method. The effects of stiffness ration as well as scarf angles on the adhesive stresses are discussed by examples. Some conclusions have been obtained from this work.
TL;DR: In this article, the transport problem for interstitial fluorine ions in M 1−xLnxF2+x (M = Ca, Sr, Ba, Pb ; Ln = La, Y, Ce, etc.) is discussed in terms of the percolation theory.
Abstract: The transport problem for the interstitial fluorine ions in M1−xLnxF2+x ( M = Ca, Sr, Ba, Pb ; Ln = La, Y, Ce , etc.) is discussed in terms of the percolation theory. An expression for the percolation threshold x c (i.e. the critical dopant amount of LnF3) is obtained and the theoretically predicted values of x c are found to be consistent with the experimental results. It appears that the percolation problem in M1−xLnxF2+x belongs to the same universality class as the standard percolation problem.