【作者】 朱聪旭；

【导师】 马南钢； 胡树兵；

【作者基本信息】 华中科技大学 ， 材料学， 2013， 博士

【摘要】 随着电子工业的繁荣和高密度封装设备的发展需要，传统的散热基板材料已经不能达到其性能要求。众所周知，单晶金刚石具有较高的热导率和较低的热膨胀系数等性能特点，因此金刚石复合材料已然成为散热基板新材料研究领域的热门。本文采用放电等离子烧结工艺，制备了具有优良热物理性能的金刚石-硅及金刚石-铜复合材料。采用场发射扫描电子显微镜（FSEM）、EDAX-能谱仪、X射线衍射（XRD）、导热系数测试仪及热膨胀系数测试仪等对材料微观组织及性能进行分析研究。金刚石-硅复合材料的研究表明，随着硅含量的增加降低了样品的烧结温度并增加了样品的相对密度；采用放电等离子原位反应技术能够制备相对密度高且热物理性能优越的Diamond/Si复合材料；烧结过程中在金刚石和硅基体界面反应产生了界面碳化硅相；硅有效降低了气孔并对金刚石在高温时的石墨化具有一定的阻碍作用；随着金刚石体积分数的增加，烧结样品的热导率急剧增加；界面微观组织尤其是基体硅与金刚石颗粒的界面键合对复合材料的热导率和热膨胀系数有直接关联；与真空烧结相比，在氩气条件下烧结得到的样品相对密度及热导率更高且热膨胀系数更低；添加烧结助剂Al的样品界面与没有添加的样品相比有很大不同，Al主要分布在硅和金刚石界面处；添加烧结助剂Al有利于提高样品的相对密度但其热导率下降；添加微量烧结助剂Ti有利于样品的致密化且能够提高样品的热导率；与采用低品质的FDP型金刚石(热导率约为1000W·m^-1·K^-1)相比较，采用高品质的MBD8型金刚石(热导率约为2000W·m^-1·K^-1)制备得到的金刚石-硅复合材料具有更优异的热物理性能。通过金刚石-铜复合材料的界面微观组织和热物理性能的研究显示，（Al, Si）包覆的金刚石颗粒均有效地提高了烧结样品的相对密度和热导率；对于Al包覆的Diamond-Cu复合材料而言，当金刚石体积分数为40%⁵0%条件下，样品热导率为491-565W/（m.K），在理论热导率的60%以上。Al包覆的金刚石-铜复合材料的热膨胀系数在Kerner模型和R-H模型理论值以下，说明了铜和金刚石颗粒之间具有较强的键接；对于Si包覆的Diamond-Cu复合材料而言，当金刚石体积分数为40%⁵0%条件下，样品热导率为450-535W/（m.K），在理论热导率的55%以上。在Maxwell-Eucken模型和Hasselman-Johnson模型基础上，考虑了相对密度对复合材料热传导理论的修正。更多还原

【Abstract】 With booming electronic industry and growing requirement for highly integrateddevices, traditional materials for radiating substrate have not fulfilled their performancerequirements. As is known to all that single crystal diamond has high thermal conductivityand low thermal expansion coefficient, so diamond composites have became hot spots inthe new material research field of radiating substrate. Diamond-Si and diamond-Cucomposites prepared by spark plasma sintering process have excellent thermo-physicalproperties in this work. The microstructures and properties of materials were analyzed byfield emission scanning electron microscope （FSEM）, EDAX-energy spectrometer, X-raydiffractometer （XRD） and testers of thermal conductivity and thermal expansioncoefficient.The research of diamond-silicon composites shows that increase of silicon contentreduced sintering temperatures and increased relative packing density obviously.Diamond-Si composites prepared by in-situ reactive spark plasma sintering yieldedexcellent thermo-physic properties and high relative density. As a result of reaction betweendiamond and silicon, SiC phase formed. This study shows that silicon facilitates reductionof porosity and hinders diamond graphitization. Thermal conductivity of samples sinteredimproved obviously with the increase of diamond content. Thermal conductivity andthermal expansion appear to be strongly related to interface microstructure, particularly tointerfacial bonding between the silicon matrix and the diamond particles. Samples sinteredin argon have remarkably high thermal conductivity and relative packing density comparedwith the samples sintered in vacuum. In the sample with trace aluminum, the Al phase isfound to be embedded in the interface between diamond and silicon. The addition ofaluminum improved relative density of samples sintered but reduced the thermalconductivity. The addition of titanium not only improved relative density of samples sintered but also increased the thermal conductivity. Compared with the use of low qualityFDP-diamond particles (thermal conductivity is about1000W·m^-1·K^-1), diamond-siliconcomposites have superior thermal physical properties via using high qualityMBD8-diamond particles (thermal conductivity is about2000W·m^-1·K^-1).The interfacial microstructures and thermal conductivities of Cu/diamond compositeswere examined. The results show that （Al or Si）-coated diamond particle is an effectiveapproach to promoting the relative packing density and improving thermal conductivity ofsamples sintered. Thermal conductivity of Al-coated diamond particles dispersed Cu-matrixcomposites containing40-50vol%diamond reached491-565W·m^-1·K^-1, higher than60%the theoretical thermal conductivity estimated by Maxwell-Eucken’s equation. Thecoefficient of thermal expansion of the Al-coated composites falls in the lines of Kernermodel and R-H model lower bound, indicating strong bonding between the Al-coateddiamond particles and the Cu-matrix in the composite. Thermal conductivity of Si-coateddiamond particles dispersed Cu-matrix composites containing40-50vol%diamond reached401-535W·m^-1·K^-1, higher than55%the theoretical thermal conductivity estimated byMaxwell-Eucken’s equation.On the basis of Maxwell-Eucken model and Hasselman-Johnson model, heatconduction theory of composite would be revised by considering relativity density.更多还原