無機物質の高温蒸発;無機物質の高温蒸発;High temperature vaporization of inorganic materials
無機物質の高温蒸発;無機物質の高温蒸発;High temperature vaporization of inorganic materials
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无机材料高温汽化;无机材料高温汽化
DOI：
10.2465/gkk1952.16.special_137
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
T. Sata
中科院分区：
文献类型：
--
作者：
T. Sata
无机材料在高温下汽化的蒸气物质是由化学式与固体相同的分子、分解的较小分子和原子及其聚合物组成的复杂混合物。获得每种物质的形成反应的平衡常数可以计算每种物质的蒸气压和热力学数据。在氧化物汽化的分解反应中，通常会放出氧气，因此气氛中的氧分压对平衡影响很大。样品在真空中的非平衡汽化称为自由汽化。由于包含取决于汽化表面原子结构的汽化系数项，因此无法从上述平衡数据准确估计自由汽化的结果。它随着温度的升高而增加，并在熔点处趋于统一。单一氧化物的蒸气压与其熔点有关，但在某些情况下与熔点有很大偏差。蒸气压和蒸发速率随着大气中氧分压的增加而降低。 Cr2O3 的蒸发速率在较低 pO2 区域随着 pO2 的增加而降低，但在达到最小值后会增加，因为形成了较高价氧化物 CrO3 和 CrO2。通过蒸发法测量，大气中水蒸气的分压通过形成氢氧化物蒸气物质加速蒸发，特别是来自碱金属和碱土金属氧化物。双氧化物材料的蒸发可以根据上述单氧化物的数据来估计，但主要蒸发组分的平衡蒸气压包括化合物或固溶体中的活性项。真空中双氧化物的自由蒸发速率通常随着时间的推移而降低。一种组分优先蒸发，剩余组分在蒸发表面形成一层（多孔或致密化合物和固溶体）。因此，蒸发速率随时间降低，由蒸发物质或离子穿过层的扩散控制，或者由于蒸气物质穿过多孔层或同成分蒸发反应的非电阻率而保持恒定。从上述知识可以理解材料中含有的微量杂质在高温下的蒸发，但也有一些杂质在基体中非常稳定的例子。
Vapor species vaporized from inorganic materials at high temperatures are complex mixtures consisting of molecules with the same chemical formulae as solid, decomposed smaller molecules and atom, and their polymers. Obtaining the equilibrium constant for the formation reactions of each species leads to calculations for the vapor pressures and the thermodynamic data for each species. In the decomposition reactions of the vaporization of oxides, oxygen gas is usually evolved, so that oxygen partial pressure in the atmosphere affects largely on the equilibrium. Non-equilibrium vaporization from the specimen in vacuum is called the free vaporization. Results in this free vaporization can not be estimated accurately from the above equilibrium data, because of containing the term of vaporization coefficient which depends on atomic structure of the vaporization surface. It increases with increasing temperatures and tends to unity at the melting point. Vapor pressures over single oxides relate to their melting points, but there are some cases which deviate considerably from them. Vapor pressure and vaporization rate decrease with increasing oxygen partial pressures in the atmosphere. The vaporization rate from Cr2O3 decreases at lower pO2 region with increasing pO2, but it increases after a minimum value, because of the formation of higher valence oxide species CrO3 and CrO2. Partial pressure of water vapor in the atmosphere accelerates the vaporization by formations of hydroxide vapor species, especially from alkali and alkaline earth oxides, as measured by the transpiraton method. Vaporizations from double oxide materials may be estimated from the data of the above mentioned single oxides, but the equilibrium vapor pressure of a predominant vaporizing component includes the term of activity in the compound or solid solution. Rate of the free vaporization from double oxides in vacuum usually decreases with time. One component vaporizes pref ereecially and remained component makes a layer (porous or dense compound and solid solution) on the vaporization surface. So the vaporization rate decreases with time, being controlled by diffusion of vaporizing species or ions through the layer, or it is constant due to non-resistivity of passing of vapor species through the porous layer or the congruent vaporization reaction. Vaporizations of minor impurities containing in materials at high temperature may be understood from the above mentioned knowledge, but there are some examples of impurities much stabilzed in the matrix.