Kinetics of Ceramic-Metal Composite Formation by Reactive Metal Penetration
Kinetics of Ceramic-Metal Composite Formation by Reactive Metal Penetration
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活性金属渗透形成陶瓷金属复合材料的动力学
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
P. Lu
中科院分区：
文献类型：
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作者：
W. Fahrenholtz;K. Ewsuk;R. Loehman;P. Lu
通过反应性金属渗透的复合材料形成的速率已被确定。金属穿透深度（即，反应层厚度）由部分反应的样品的横截面测量。将致密的莫来石预制件浸入温度为900°-1300 ° C的熔融铝浴中，并使组合物反应长达250 min。通常，反应层厚度随时间增加而线性增加。渗透率高达6.0 mm/h的测量，然而，铝渗透率随时间和温度的变化显着。反应温度从900°C升高到1100°C时，渗透速率增加，反应层厚度在此温度范围内随时间的增加而线性增加。在1150°C及以上的温度下，由于反应界面附近的硅浓度增加，反应层的形成在相对短的快速线性生长期后减慢或停止。快速线性生长期的持续时间从1150°C下的25 min减少到1250°C下的<1 min。在1300°C及以上的温度下，通过使用光学显微镜没有检测到反应层。动力学数据和透射电子显微镜分析表明，该反应被抑制在较高的反应温度和较长的时间，因为在反应前沿的硅积累和饱和。计算表明，随着反应温度的升高，硅的生成量的增加速度大于硅的输运速度。在1100°C的温度下，这两个速率大致相等。
The rate of composite formation via reactive metal penetration has been determined. The metal penetration depth (i.e., the reaction-layer thickness) was measured from cross sections of partially reacted samples. Samples were fabricated by immersing dense mullite preforms in a bath of molten aluminum at temperatures of 900°–1300°C and reacting the combination for up to 250 min. In general, the reaction-layer thickness increased linearly as the time increased. Penetration rates as high as 6.0 mm/h were measured; however, the aluminum penetration rate varied dramatically with time and temperature. The penetration rate increased when the reaction temperature was increased from 900°C to 1100°C, and the reaction-layer thickness increased linearly as the time increased in this temperature range. At temperatures of 1150°C and above, reaction-layer formation slowed or stopped after a relatively short period of rapid linear growth, because of an increase in silicon concentration near the reaction interface. The duration of the rapid linear growth period decreased from 25 min at 1150°C to <1 min at 1250°C. At temperatures of 1300°C and above, no reaction layer was detected by using optical microscopy. Kinetics data and transmission electron microscopy analysis suggest that the reaction was inhibited at higher reaction temperatures and longer times, because of silicon buildup and saturation at the reaction front. Calculations show that, as the reaction temperature increased, the silicon production increased faster than the silicon transport. The two rates were approximately equal at a temperature of 1100°C.