【作者】 李守林；

【导师】 杨君友；

【作者基本信息】 华中科技大学 ， 材料学， 2006， 硕士

【摘要】 梯度热电材料把两种或两种以上的单一材料结合在一起,使每种材料都工作在各自最佳温度区间,这样既扩大了材料的应用温度范围,又有效利用了各段材料的ZT值,因此可大幅度地提高材料的热电性能。本论文研究了不同La含量时LaxNi0.2Co3.8Sb12均质填充Skutterudite材料的热电性能;用热压烧结方法制备了具有不同过渡层的p型La0.4FeCo3Sb12/Bi2Te3梯度热电材料,并对梯度结构材料的界面特性和热电性能进行了研究,对梯度结构材料进行了模拟计算。研究结果表明:对于填充Skutterudite的均质材料,用机械合金化热压烧结的方法制备了不同La含量时LaxNi0.2Co3.8Sb12材料(x=0.1,0.3,0.5,0.7)。随着La含量的增加,材料的Seebeck系数、电阻率及热导率均有不同程度地减小,而材料的热电性能得到显著提高。在390℃时,La0.3Ni0.2Co3.8Sb12的ZT值只有0.22,而La0.5Ni0.2Co3.8Sb12和La0.7Ni0..2Co3.8Sb12材料热电性能较好, ZT值分别为0.31和0.29。对无过渡层和分别以Fe、Ni、Al金属薄片为过渡层的p型La0.4FeCo3Sb12/Bi2Te3分段梯度复合材料,通过FESEM界面形貌观察以及EDAX界面成分分析,结合热电性能的测量,综合评估了使用不同界面过渡层的梯度热电材料的成分组元扩散情况及其热电性能。结果表明,使用Fe为界面层时,p型La0.4FeCo3Sb12/Bi2Te3梯度材料界面处连接紧密,能有效阻止界面两侧元素的扩散,热电功率因子α2σ为1.796mWm-1K-2,具有相对较好且稳定的热电性能。对梯度热电材料结构及性能进行了计算机模拟,编写了相应的计算机模拟软件,从界面处无扩散和有扩散时两种情形下模拟计算了梯度结构材料的热电性能,模拟结果与实验所得的结论相符得较好。更多还原

【Abstract】 Functionally graded thermoelectric materials(FGTM), with optimized design and consolidation of different monolithic thermoelectric materials which have different working temperature range, could work over a wide temperature range and make full use of figure of merit of every component material, therefore its thermoelectric properties and thermoelectric conversion efficiency could be improved remarkably.In this thesis, LaxNi0.2Co3.8Sb12 filled skutterudites with different La filling content (x=0.1,0.3,0.5,0.7) were prepared by mechanical alloying and hot pressing, effect of La content on thermoelectric properties of LaxNi0.2Co3.8Sb12 was studied and discussed. P-type La0.4FeCo3Sb12/Bi2Te3 FGTM were prepared with different junction layers by hot press sintering and their interface characteristics and thermoelectric properties were studied subsequently, and a computer simulation and calculation for FGTM were also performed. The main results are shown as follows:With increasing the La content, the Seebeck coefficent, electrical resistivity and thermal conductivity of LaxNi0.2Co3.8Sb12 filled skutterudites decreased more or less, and the thermoelectric properties improved remarkably. At 390℃, the ZT value of La0.3Ni0.2Co3.8Sb12 was 0.22, while the ZT values of La0.5Ni0.2Co3.8Sb12 and La0.7Ni0.2Co3.8Sb12 were 0.31 and 0.29, respectively.The interface morphologies and element diffusion of p-type La0.4FeCo3Sb12/Bi2Te3 with different joint materials were characterized by FESEM and EDAX. Power factor was calculated and used to evaluate thermoelectric properties of the FGTM. As a result, p-type La0.4FeCo3Sb12/Bi2Te3 with Fe junction layer, which had good bond with both segments at interface and prevented elements from diffusing to opposite side, got a better power factor, 1.796mW·m-1·K-2, and had a relative good and steady performance.A computer software was written and a simulation was performed to the FGTM with consideration of two different interface situations: with diffusion and without diffusion. The results of simulation are in good accordance with that of experiments.更多还原