基于负热膨胀颗粒的低热膨胀、高导热复合材料的设计、制备及性能调控

By loading negative thermal expansion (NTE) particles, cupreous matrix composites with low thermal expansion, high heat conducting and good processability will be designed and prepared. The composition and microstructure will be designed by computer simulation and then verified by experiments to get numerical model, which can be used to adjust the structure and properties of the composites. Laser micro-texture sculpt, surface modification of NTE particles and vacuum hotpressing (or hot finishing) techniques will be used to prepare the composites to guarantee the effective diffusion bonding between NTE particles and cupreous matrix. NTE particles in the composites will be distributed orderly and have specific microstructure as designed by computer. Effects of the characteristcs of particles (loading ammount, morphology and size, distribution mode) and the key preparation parameters on the thermal performances of the composites will be investigated and the relationship will be revealed. Results obtained in this study will promote the application of this composite material in high technology industry.

以低膨胀、高导热复合材料为研究对象，引入负热膨胀(NTE)无机颗粒为复合相，重点通过计算机模拟辅助设计、实验制备、性能表征相结合，建立相互间内在联系，获得具有组织结构与性能双向设计功能的数值模型。运用激光精确微造型、NTE颗粒表面改性和真空热压（或热精轧）技术，实现有效扩散粘结，所获复合材料具有与设计目标相对应的颗粒有序分布和微结构，实现在较低填充量下有效降低金属基材的热膨胀系数并保持良好的导热特性和可加工型，并揭示颗粒相特征值（填充量、形貌尺寸、分布状态）、关键制备参数对复合材料热学特性的影响规律，实现性能的主动调控，为该类材料的高技术应用奠定基础。

本项目针对铜（Cu）基热沉与芯片材料之间存在过大的热膨胀系数不匹配的现象展开研究，提出以负热膨胀（NTE）材料为复合相，制备NTE/Cu复合材料以解决热沉材料低膨胀和高热导之间的协调与统一。首先，在计算机辅助下进行Cu/Sc2W3O12的设计和模拟复合研究，获得相应的关键制备参数（坑的形状、坑的间距、层间的叠加模式），借助激光精密刻蚀技术实现Sc2W3O12颗粒在Cu基体中复合量和空间分布状态的精确和主动控制；分别采用固相法和水热法成功合成了高纯度的Sc2W3O12，通过氧化石墨烯（GO）实现了对Sc2W3O12形貌和负热膨胀性能的调控；在此基础上，开展了制备方法及热性能的研究，发现：通过调节Sc2W3O12的复合量，可以调节复合材料的热膨胀性能。在室温~300℃内，Sc2W3O12/GO/Cu复合材料的热膨胀系数皆线性一致，随着Sc2W3O12的质量分数的改变，其热膨胀系数可以控制在4~14×10-6 K-1之间，导热可以达到200~245W/(m∙K)。