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ULF DWORAK HANS OLAPINSKI WOLFGANG BURGER 《Journal of the American Ceramic Society》1986,69(7):578-579
The dilatation behavior of two grades of partially stabilized zirconia (PSZ) was determined. ZN 40 is a material which contains 40% to 50% t -ZrO2 particles, and has a reproducible dilatometric behavior up to 900°C. ZN 50 is a Mg-PSZ containing 20% to 30% of the monoclinic phase. The cyclic dilatation curves show an unstable hysteresis effect which arises from the tetragonal-monoclinic phase transformation. 相似文献
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A detailed numerical study has been made of the dissolution kinetics of particles in binary alloys during isothermal annealing.
In earlier models, the assumption was made that the dissolution reaction could be described by the dissolution of only one
particle in an infinite matrix or the dissolution of a regular array of particles of equal size. This assumption has been
relaxed and a log-normal size distribution of particles has been introduced instead. The calculations have been done numerically
by applying a finite difference technique to a spherical particle in a spherical cell of finite size. The presence of a size
distribution of particles was found to have a great effect on the dissolution kinetics and, therefore, must be included in
a reliable model for the dissolution of particles. The results have been presented in diagrams, giving the volume fraction
as a function of the dimensionless annealing time with the geometrical standard deviation as a parameter, and thus should
be useful in making accurate predictions of the dissolution kinetics of binary alloys. The curves can be used for all volume
fractions provided that all of the particles can be dissolved completely at the temperature considered. Also, equations have
been derived that can easily be used to give an estimate of the annealing time to dissolve 90 pct of the initial volume fraction. 相似文献
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This paper comments on a technical problem arising in the article ‘ Precision tracking control of non-minimum phase systems with zero phase error’ by Xia and Menq. 相似文献
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A detailed experimental study of the dissolution kinetics of Si particles in an Al-Si alloy has been carried out in order
to test the validity of the two models presented in the accompanying article.[1] In these models, the dissolution kinetics
are dependent on the particle size distribution of the alloy. An alloy with composition Co = 0.77 at. pct Si was heat-treated in order to obtain rather coarse spherical particles (1 to 10 μn). The size distribution
of the particles was found to be close to the log-normal distribution. At high temperatures, when the solvus concentration
was well above Co, the experimental values were very close to the values of the model which predicted the highest dissolution rates. At lower
temperatures, when the solvus concentration was closer toC
o, the experimental values lay in between the values predicted by the two models. The results clearly demonstrate that a size
distribution of particles must be included in the model if an accurate prediction of the dissolution kinetics is to be achieved. 相似文献
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