Yttria-stabilized zirconia-based composites with adaptive thermal conductivity
Yttria-stabilized zirconia-based composites with adaptive thermal conductivity
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DOI：
10.1016/j.compscitech.2010.08.010
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发表时间：
2010-11-30
影响因子：
9.1
通讯作者：
Gord, James R.
中科院分区：
文献类型：
--
作者：
Gengler, Jamie J.;Muratore, Christopher;Gord, James R.
采用时域热反射（TDTR）技术研究了“变色龙涂层”薄膜的热导率变化趋势。一种氧化钇稳定的氧化锆（YSZ）基纳米复合材料，其含有类似于21体积%的氧化钇稳定的氧化锆（YSZ）。本研究采用银（Ag）。用TDTR测量沉积态复合膜的热导率（k），发现其值为7.4 +/- 1.4 W m（-1）K（-1）。然后将膜在500摄氏度下退火1小时，以刺激Ag从复合材料内通过扩散流到表面。在退火过程中聚结在表面上的Ag被去除以暴露下面的多孔YSZ基质，并且样品用TDTR技术重新检查。然后测量多孔纳米复合材料YSZ材料的热导率为1.6 +/- 0.2 W m（-1）K（-1），其显著低于纯纳米晶体YSZ的完全致密对照样品（2.0 +/- 0.1 W m（-1）K（-1））。与对照样品相比，退火的膜显示出热导率降低20%，与沉积态材料相比，热导率降低4-5倍。实验证明了温度触发的复合材料，导致自修改的热导率和扩散控制的孔隙率。这些方面可用于增强或限制热传输（即，热开关）。的TDTR技术测量薄，纳米多孔膜材料的适用性也得到了证明。(C)2010爱思唯尔有限公司版权所有。
Thermal conductivity trends in a "chameleon coating" thin film were characterized with a time-domain thermoreflectance (TDTR) technique. A yttria-stabilized zirconia (YSZ)-based nanocomposite material containing similar to 21 vol.% silver (Ag) was employed for this study. The thermal conductivity (k) of the asdeposited composite film was measured with TDTR and found to have a value of 7.4 +/- 1.4 W m(-1) K(-1). The film was then annealed at 500 degrees C for 1 h to stimulate Ag flow from within the composite to the surface via diffusion. The Ag that coalesced on the surface during annealing was removed to expose the underlying porous YSZ matrix, and the sample was reexamined with the TDTR technique. The thermal conductivity of the porous nanocomposite YSZ material was then measured to be 1.6 +/- 0.2 W m(-1) K(-1), which is significantly lower than a fully dense control sample of pure nanocrystalline YSZ (2.0 +/- 0.1 W m(-1) K(-1)). The annealed film displayed a 20% reduction in thermal conductivity as compared to the control sample and a 4-5-fold reduction in thermal conductivity as compared to the as-deposited material. The experiments demonstrate temperature triggering of a composite material, resulting in selfmodifying thermal conductivity and diffusion-controlled porosity. These aspects can be used to enhance or restrict thermal transport (i.e., a thermal switch). The applicability of the TDTR technique to measurements of thin, nanoporous film materials is also demonstrated. (C) 2010 Elsevier Ltd. All rights reserved.