CFRC电导率的高密度缺陷界面电子气解耦强化机理与方法研究

Energy consumption of pavement resistance heating for deicing and snow removal in winter can be reduced greatly by Peltier effect of carbon fiber reinforced cement-based composites (CFRC). However, decoupled electric conductivity of CFRC has to be increased before realizing this application. Up to the present, the enhanced mechanism and method are not clear. The behavior of CFRC electric conductivity and the coupling behavior between CFRC electric conductivity and Seebeck coefficient are greatly different from the crystalline thermoelectric materials, because of the extreme density microstructure defects in CFRC which consist of polytype defect interfaces. In addition, the decoupled enhanced theory for electric conductivity of relative cement-based materials has not been reported until now. In our previous research, the electric conductivity of CFRC was increased and decoupled with holding Seebeck coefficient at a high value, by increasing the content of interface between metallic oxide or carbon fiber and cement matrix. Take into account these results, the effect of defect interfaces in CFRC on carrier transport will be first researched to explain the strong effect mechanism of high density defect interfaces on CFRC electric conductivity. After the two-dimensional electron gas is introduced into the defect interfaces, the effect of electron gas on carrier mobility along the network of high density defect interfaces in CFRC will be also researched. Then, the decoupled enhanced mechanism of CFRC electric conductivity via cooperative action of high density defect interfaces and two-dimensional electron gas can be made clear. Finally, the decoupled enhanced method of CFRC electric conductivity by material technology and the estimation of energy consumption for pavement deicing and snow removal by CFRC-Peltier effect will be obtained. In this work, the electric conductivity enhanced mechanism of cement-based materials will be explained from a new perspective, and a new approach reducing energy consumption of pavement resistance heating for deicing and snow removal will be provided.

碳纤维水泥基复合材料（CFRC）Peltier效应能显著降低冬季路面热融除雪能耗，但解耦提高其电导率并稳定Seebeck系数是应用前提，确切的强化机理和方法尚未明确。CFRC具有的高密度微观结构缺陷（本质为多类型界面组合）使其电导率行为规律和电导率-Seebeck系数耦合规律与晶态热电材料显著不同，水泥基材料电导率解耦强化的相关理论，迄今国内外也尚无报道。本课题前期研究发现，增加碳纤维或金属氧化物与基体界面的界面密度，可显著提高CFRC电导率并稳定Seebeck系数。在此基础上，本课题将通过缺陷界面对载流子输运过程的影响研究，阐明高密度缺陷界面对CFRC电导率强烈影响的微观机制，然后在缺陷界面构造二维电子气异质界面，研究电子气对高密度缺陷界面载流子输运过程迁移率的影响规律，阐明CFRC电导率的高密度缺陷界面电子气解耦强化机理，获得电导率解耦强化的工艺方法，为降低路面热融除雪能耗提供新途径。

碳纤维水泥基复合材料（CFRC）Peltier效应可有效降低热融除雪能耗，在道路低能耗热融除雪领域具有重要应用前景。本项目研究了高密度缺陷界面对CFRC电导率和热电性能参数的强烈影响规律，采用复合材料工艺在CFRC界面构造电子气异质界面层和界面改性，研究其对复合材料热电性能和载流子输运过程的影响规律，大幅解耦提高CFRC电导率，并研究了环境载荷对CFRC热电性能的影响规律。主要研究结果有：（1）碳纤维酸处理工艺改性复合材料界面，可有效提高CFRC热电性能；酸处理时间延长，CFRC电导率逐渐降低，Seebeck系数、热导率、功率因数和热电优值逐渐增加；水泥基复合材料孔隙率逐渐增加，抗压强度逐渐减小；（2）在复合材料界面构造了均匀的ZnMgO/ZnO电子气异质界面层，Mg离子有效掺杂到ZnO晶格中，显著提高了CFRC电导率；（3）膨胀石墨水泥基复合材料电导率在半导体范围内，为热激发载流子所控制，并随温度升高缓慢增加。含15.0wt.%膨胀石墨CFRC具有最高的热电优值，其载流子迁移率为681.43cm2•v-1•s-1；（4）碳纳米管水泥基复合材料的功率因数和热电优值，随着碳纳米管含量的增加缓慢提高；（5）离子液体界面改性显著提高了CFRC的综合热电性能；（6）氧化物缺陷改性解耦提高了CFRC电导率，并稳定Seebeck系数，获得了较高的功率因数；（7）Peltier效应在水泥基复合材料试样表面可产生明显的温差，达10oC；（8）疲劳载荷会降低CFRC电导率，使其Seebeck系数绝对值先增大后减小；低温循环载荷会增加材料内部微裂纹数量，降低载流子的迁移率，使得材料电导率和Seebeck系数绝对值下降；冻融循环载荷也会降低水泥基材料的热电性能。通过上述结果，阐明了CFRC电导率的高密度缺陷界面电子气解耦强化机理，获得其电导率解耦强化的工艺方法，为降低路面热融除雪能耗提供了新途径。