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首页> 外文期刊>Thermochimica Acta: An International Journal Concerned with the Broader Aspects of Thermochemistry and Its Applications to Chemical Problems >THERMAL PROPERTIES AND DEVITRIFICATION BEHAVIOUR OF (2.5-X)CAO.X/3Y(2)O(3).2SIO(2)
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THERMAL PROPERTIES AND DEVITRIFICATION BEHAVIOUR OF (2.5-X)CAO.X/3Y(2)O(3).2SIO(2)

机译：（2.5-X）CAO.X / 3Y（2）O（3）.2SIO（2）的热性质和失偏行为

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摘要

The effect on thermal properties and non-isothermal devitrification of substituting CaO by Y2O3, in a glass of composition 2.5 CaO.2SiO(2) was studied. The glass samples were submitted to thermal analysis (DTA) and X-ray diffraction analysis. The trends with the composition of the glass transformation, T-g, softening, T-s temperature and the activation energy of crystal growth, E-c, can be explained on the basis of the increase of the structural rigidity when Ca2+ ions are substituted by Y3+ ions; stronger bonds to the oxygen are, indeed, expected. In all the devitrified samples CaO.SiO2 crystals form together with a secondary calcium silicate phase. The pattern of the Y2O3 free glass shows that the alpha CaO.SiO2 is also formed in the temperature range 900-1000 degrees C. When x = 1.0 a new, crystalline phase appears, which could not be identified by means of JCPDS cards. The activation energy for crystal growth was E-c = 640 +/- 25.1 kJ/mole, regardless of composition. Devitrification involved a mechanism of surface nucleation: however, as the samples softened and sintered before devitrifying, surface nuclei behaved as bulk nuclei. (C) 1997 Elsevier Science B.V. [References: 21]
机译：研究了组成为2.5 CaO.2SiO（2）的玻璃中Y2O3取代CaO对热性能和非等温失透的影响。将玻璃样品进行热分析（DTA）和X射线衍射分析。玻璃化转变的组成，T-g，软化，T-s温度和晶体生长的活化能E-c的趋势可以基于当Ca2 +离子被Y3 +离子取代时结构刚度的增加来解释。的确，与氧的键更强。在所有失透的样品中，CaO.SiO2晶体与第二硅酸钙相一起形成。不含Y2O3的玻璃的图案表明，在900-1000摄氏度的温度范围内也形成了αCaO.SiO2。当x = 1.0时，出现了新的结晶相，无法通过JCPDS卡识别。晶体生长的活化能为E-c = 640 +/- 25.1 kJ / mol，与成分无关。失透涉及表面成核的机制：但是，由于样品在失透之前软化和烧结，表面核表现为整体核。 （C）1997 Elsevier Science B.V. [参考：21]

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