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研究了难熔金属铱与SiC及铱与Y2O3的固相反应,采用金属间化合物的标准生成吉布斯自由能等于标准形成焓的方法计算固相反应热力学,采用电子分布与晶体结构之间相关的Engel理论分析了铱与Y2O3的固相反应机制。结果表明,铱与SiC在1000℃开始反应生成Ir3Si和石墨,随着反应温度升高,Ir3Si与SiC进一步反应生成更高熔点的IrSi,当反应温度为1400℃时,固相反应产物为IrSi和石墨。在1800℃的还原性碳气氛下,铱与Y2O3能够发生固相反应生成Ir2Y和CO,Ir外围电子层失去电子形成d5sp2排布,Y外围电子层得到电子形成d3sp排布,成键电子数目由17个增加至21个,导致Ir-Y键能大于Y-O键能。
The solid-state reaction of iridium with SiC and iridium and Y2O3 was studied. The thermodynamics of solid-state reaction was calculated by the standard Gibbs free energy equivalent to the standard formation enthalpy of intermetallic compound. The correlation between electron distribution and crystal structure The Engel theory analyzes the solid-state reaction mechanism of iridium and Y2O3. The results show that Ir3Si and graphite begin to react with SiC at 1000 ℃. Ir3Si reacts with SiC to form higher melting point IrSi as the reaction temperature increases. When the reaction temperature is 1400 ℃, the products of the solid reaction are IrSi and graphite. In 1800 ℃ reductive carbon atmosphere, iridium and Y2O3 solid-state reaction can produce Ir2Y and CO, Ir peripheral electron layer loses electrons to form d5sp2 arrangement, Y outer electron layer to form d3sp electron distribution, the number of bonding electrons from 17 to 21, resulting in Ir-Y bond energy greater than the YO key.