基于3D打印构筑的高面间热导率氮化硼陶瓷的制备

Boron nitride ceramics with high interfacial thermalconductivity based on direct ink writing

氮化硼(BN)陶瓷具有高纵横比、耐高温、高导热和电绝缘性等优异性能,广泛应用于电子信息、航天航空、冶金、机械等领域。3D打印技术与传统加工方式相比具有低成本和省时等特点,是制备具有复杂三维结构陶瓷制件的重要成型技术。为此,基于自主研发的气压式新型直写3D打印材料成型平台,使用BN和聚乙烯醇(PVA)作为原料和粘结剂,制备了不同BN含量的陶瓷浆料,利用逐层堆积原理,设计并制备具有不同三维结构的陶瓷预制件,通过改变浆料的流变学特性,在打印过程中实现了BN二维纳米片在剪切力作用下的取向,得到了高面间热导率的陶瓷材料。研究了BN含量对陶瓷制件成型质量的影响,并且采用了XRD和SEM对打印得到的陶瓷材料的结构和微观形貌进行了表征。结果表明,BN/PVA 85浆料有着良好的剪切变稀特性和黏弹性,在线性黏弹性区的屈服应力达到240 Pa,适配于直写成型3D打印技术。BN在制件内部的水平取向度提高有助于增强陶瓷材料的面间热导率,其中,BN/PVA 85陶瓷制件的面间热导率约为4.3 W/(m·K)。

Boron nitride(BN)ceramics have excellent properties such as high aspect ratio,high temperature resistance,high thermal conductivity and electrical insulation,widely used in electronic information,aerospace,metallurgy,machinery and other fields.3D printing technology has low cost and time-saving compared with traditional processing methods,and is an important molding technology for the preparation of ceramic parts with complex three-dimensional structure.To this end,in this paper,based on the self-developed pneumatic new direct-write 3D printing material forming platform,ceramic slurries with different BN contents were prepared using BN and polyvinyl alcohol(PVA)as raw materials and binder,and ceramic preforms with different 3D structures were designed and prepared using the layer-by-layer stacking principle.By changing the rheological properties of the slurries,the BN 2D nanosheets were realized in the printing process under the shear.By changing the rheological properties of the slurry,the orientation of BN 2D nanosheets under the action of shear force was achieved during the printing process,and ceramic materials with high interplanar thermal conductivity were obtained.The effect of BN content on the molding quality of the ceramic parts was investigated,and the structure and microscopic morphology of the printed ceramic materials were characterized by XRD and SEM.The results show that the BN/PVA 85 slurry has good shear thinning and viscoelastic properties,and the yield stress in the linear viscoelastic region reaches 240 Pa,which is suitable for direct-writing 3D printing technology.the increased horizontal orientation of BN inside the part contributes to the enhanced interfacial thermal conductivity of the ceramic material,where the interfacial thermal conductivity of the BN/PVA 85 ceramic part is about 4.3 W/(m·K).