Research on multi-layer type of Peltier cooling micro-devices by assembling thermoelectric particles

近年来，新型热电材料的开发和热电器件的制造技术取得了很大的进步，人们为扩大热电的应用范围做出了许多努力。另一方面，微型机械、微型计算机和中央处理器在各种便携式产品中得到了广泛的应用。这些趋势对小型电源或局部冷却装置提出了特殊的要求。为了制造热电模块或器件，通常需要几个工艺过程。主要工序包括热电材料的制备、切削、TE材料与电极的连接。如果我们需要一个小的模块，大约需要几毫米的尺寸，TE材料应该切得更小。这将给组装高质量的热电器件带来很多困难，因为大多数热电材料都很脆，很难切割成非常小的块，尤其是在低温度下使用的热电材料。为了解决这一问题，小颗粒和烧结模块的组装应该是一种有效的选择。单尺寸颗粒的组装技术也可以很容易地应用于组成功能梯度的热电器件或其他结构。采用脉冲孔喷射法（POEM）制备了含铋锑合金热电材料球的高精度单尺寸颗粒。这使我们能够进行单尺寸颗粒的组装和烧结工艺的研究。火花等离子烧结（SPS）和等离子活化烧结（PAS）是烧结和连接块状热电材料的有效方法。SPS很难用于微颗粒的烧结，但考虑到使用直流电。用普通电炉也可以制备烧结的单尺寸热电颗粒，但其微观结构控制困难且耗时长。本课题旨在探索一种有效的烧结单尺寸热电颗粒的制备方法，并对通过放电烧结制备微热电器件进行了探讨。表征结果表明，放电烧结的单尺寸颗粒具有较好的性能，并且我们认为5w / s的放电条件可以使热电性能达到平衡的高水平。室温下放电烧结的Seebeck结果约为82 μ V/K，接近实际Bi-Sb合金的数值。少

Recent years, technology on development of new thermoelectric (TE) materials and fabrication of thermoelectric device has been made much progress and many efforts are made to extend the application of thermoelectric. On the other hand, micro-machine, microcomputer and CPU have been used in a lot of field in various portable products. These trends make a specific request for small-sized electric source or for local cooling device.In order to fabricate a thermoelectric module or a device, usually several technique processes are needed. The main procedures include preparation of thermoelectric materials, cutting, joining of TE material with electrode. If we need a small module that is required about the size of several millimeters, the TE material should be cut smaller. This will make a lot of difficulties for assemble a high quality thermoelectric device since most thermoelectric materials are brittle and hard to be cut in very small pieces especially for TE materials those used at low t … More emperature. To solve this problem, assembly of small monosized particles and a sintered module should be an effective choice. The assembling technique for monosized particles can also be easily applied to compose a functionally graded thermoelectric device or other structures. The authors have prepared high accuracy monosized particles including thermoelectric materials balls of Bi-Sb alloy by pulsated orifice ejection method (POEM). These enable us to do the research of assembling and sintering process of monosized particles.For sintering and joining of bulk thermoelectric materials, the method of spark plasma sintering (SPS) and plasma activated sintering (PAS) are effective processes. The SPS is difficult to use to the sintering of micro particles but in the view of using direct current. The preparation of sintered monosized thermoelectric particles is also can be done by a normal electric furnace, however, we found it is very difficult to control the microstructure and it takes long time. The project is take the aim at developing of an effective method for preparing of sintered monosized thermoelectric particles, and makes some approach to compose micro-thermoelectric device through the discharge sintering.The characterization results indicate that the discharge-sintered monosized particles shows better properties compared with others, and we consider the condition of electric discharge at 5 watt per second led the thermoelectric properties to a balanced high level. The result of Seebeck at room temperature for discharge sintering is around 82 μ V/K, it is near value from the bulk practical Bi-Sb alloy. Less