Fabrication of machinable AlN-BN composites with high thermal conductivity by pressureless sintering turbostatic BN-coated AlN nanocomposite powders
Fabrication of machinable AlN-BN composites with high thermal conductivity by pressureless sintering turbostatic BN-coated AlN nanocomposite powders
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DOI：
10.1557/jmr.2008.0022
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发表时间：
2008-01-01
影响因子：
2.7
通讯作者：
Niihara, Koichi
中科院分区：
文献类型：
--
作者：
Kusunose, Takafumi;Sekino, Tohru;Niihara, Koichi
为了赋予硬脆AlN陶瓷可加工性而不损失其高导热性，研究了细BN颗粒在AlN基体中的均匀分散。通过无压烧结涡轮增压BN包覆的AlN纳米复合粉末（AIN-BN纳米复合粉末）获得BN颗粒的均匀分散，所述AIN-BN纳米复合粉末通过还原和加热含有硼酸、尿素和碳的混合物的AlN颗粒制备。虽然AlN在还原过程中被硼酸轻微氧化，但碳的加入通过碳热还原氧化的AlN颗粒降低了AIN-BN复合粉末的氧含量。结果，烧结材料的热导率随着纳米复合材料粉末的氧含量的降低而增加。AIN-BN纳米复合材料含有超过20体积%的BN表现出高强度，机械加工性，和相对较高的热导率相比，与传统的微复合材料。
To impart machinability to hard and brittle AIN ceramics without losing their high thermal conductivity, a homogeneous dispersion of fine BN particles in an AIN matrix was investigated. A homogeneous dispersion of BN particles was obtained by pressureless sintering of turbostatic BN-coated AIN nanocomposite powder (AIN-BN nanocomposite powder), which was prepared by reducing and heating AIN particles containing a mixture of boric acid, urea, and carbon. Though AIN is slightly oxidized by boric acid during the reduction, the addition of carbon reduced the oxygen content of the AIN-BN composite powder by carbothermal reduction of the oxidized AIN particles. As a result, the thermal conductivity of the sintered material increased with decreasing oxygen content of the nanocomposite powder. AIN-BN nanocomposites containing more than 20 vol% BN showed high strength, machinability, and relatively high thermal conductivity in comparison with the conventional microcomposites.