多媒體教案-材料物理性能學(xué)-04-材料的熱性能-2016-au

1、材料的熱學(xué)性能是宏觀物質(zhì)的體效應(yīng)體效應(yīng)，能夠反映材料內(nèi)部的結(jié)構(gòu)特性，熱容、熱導(dǎo)率、熱膨脹和熱應(yīng)力都是材料工程應(yīng)用中不可忽略的方面，值得人們進(jìn)行深入探索研究。自由度自由度 (degree of freedom)kTm23212ktvkTmmmzyx21212121222vvvyzxo分子平均平動(dòng)動(dòng)能分子平均平動(dòng)動(dòng)能222213xyzvvvv 單原子分子平均能量單原子分子平均能量kT213RkNTECVmV330RkNTECVmV330)21( nEn1expTkEB220 1)/exp()/exp()(3TkTkTkkNTECBBBBVmVmax03)(vNdvvg1exp1)(kTEEEfF3

2、332220000! 31! 21)()(xdrUdxdrUdxdrdUrUrUrrr)(121121TTlllTlll)(TgraddxdTqvlCv31231FvevCFFEmv 221FBemTnk322TmnemTnkFFBe222/3TLe0/TLTTTphphe0)/(BABabNNeTkEln溫差發(fā)電器溫差發(fā)電器In 1822, the EstonianGerman physicist Thomas Johann Seebeck (inset) discovered that if heat is applied across the junction of two wires,

3、 a current is generated. It is the basis of thermocouples devices used for cooling, and for power generation such as in the Voyager mission to Jupiter and Saturn, seen here at its launch in 1977.An inconvenient truth about thermoelectricsCronin B. Viningature materials | VOL 8 | FEBRUARY 2009 1821年，德國(guó)物理學(xué)家塞貝克（T.J. Seebeck）發(fā)現(xiàn)，在兩種不同的金屬所組成的閉合回路中，當(dāng)兩接觸處的溫度不同時(shí)，回路中會(huì)產(chǎn)生一個(gè)電勢(shì)，這就是熱電效應(yīng)。也稱作“塞貝克效應(yīng)（Seebeck effect）”。Thomas Johann Seebeck（17701831）ZT=S2T/(ke+kl)四級(jí)制冷芯片An inconvenient truth about thermoelectricsCronin B. Viningature materials |