熔盐法制备金红石晶须及其对硅橡胶介电性能的影响

发布时间：2018-03-30 03:35

  本文选题：金红石晶须　切入点：熔盐法　出处：《河南科技大学》2017年硕士论文

【摘要】：陶瓷/聚合物复合材料作为柔性基板具有高机械弹性、低介电常数、低介质损耗、高热导率、低热膨胀系数等优异性能。陶瓷晶须具有优异的物理化学性能,相对于陶瓷颗粒能进一步提高复合材料的介电性能、热学性能、力学性能和摩擦性能等。本实验分别把金红石晶须、微米颗粒和纳米颗粒及其改性后粉体加入107硅橡胶中经室温固化制备了复合材料,系统的研究金红石形态和体积分数及改性对复合材料微波介电性能的影响。金红石晶须采用熔盐法制备,以无定形Ti O2、ZnSO4·7H2O和Na2SO4按照1:1:1摩尔比混合为原料,加热方式分别采用常规加热和微波加热,通过设计合理的实验方案研究加热温度,升温速率和保温时间对金红石晶须形貌的影响。在微波加热条件下,以升温速率15℃/min,煅烧温度700℃保温15min,合成了形貌良好的金红石晶须,其直径约0.5μm,长径比约为25,与常规加热相比加热温度降低了100℃,保温时间由4h缩短到15min,这是由于微波加热能对材料进行整体而均匀的加热。随着金红石填料体积分数的增加,复合材料的εr和τf逐渐增大,Q×f逐渐减小。在同等体积分数下,金红石晶须/硅橡胶复合材料的εr略大,纳米颗粒次之,微米颗粒最小;对于Q×f,在相同添加量下,金红石晶须/硅橡胶复合材料的最大,其次是微米颗粒,纳米颗粒最小;这可能与金红石填料的不同形态有关。金红石粉体用KH570改性后,三种复合材料的εr和Q×f均得到提高,当金红石填料体积分数为19%时,改性金红石晶须/硅橡胶复合材料的εr=3.645,Q×f=3655GHz,τf=+45.6ppm/℃。实验把复合材料在1MHz和微波频率下的εr试验值分别与Lichtenecker模型、Maxwell-Garnet模型和Jayasundere-Smith模型进行了比较。发现在1MHz下,复合材料的εr试验值与三种模型的理论值基本相符,在微波频率下,试验值比理论值偏低,随着金红石填料体积分数的增大,偏差越来越大,与Maxwell-Garnet模型最为接近。同时还研究了复合材料的吸水率对其微波介电性能的影响。随着浸泡时间的增加,复合材料的吸水率越来越大。在相同浸泡时间下,金红石晶须/硅橡胶复合材料的吸水率最大,纳米颗粒次之,微米颗粒最小。在微波频率下,随着复合材料吸水率的增加,复合材料的εr基本没有变化,Q×f逐渐减小。
[Abstract]:As a flexible substrate, ceramic / polymer composites have excellent properties such as high mechanical elasticity, low dielectric constant, low dielectric loss, high thermal conductivity and low thermal expansion coefficient. Compared with ceramic particles, the dielectric properties, thermal properties, mechanical properties and friction properties of composites can be further improved. The composite materials were prepared by adding micron particles and nano-particles and their modified powders into 107 silicone rubber at room temperature. The effects of morphology and volume fraction of rutile and modification on microwave dielectric properties of composites were systematically studied. Rutile whiskers were prepared by molten salt method and mixed with amorphous TIO _ 2O _ 2ZnSO _ 4 7H2O and Na2SO4 at 1:1:1 molar ratio. The effects of heating temperature, heating rate and holding time on the morphology of rutile whisker were studied by designing a reasonable experimental scheme. Rutile whiskers with good morphology were synthesized at the heating rate of 15 鈩，

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