多尺度碳基水泥复合材料的导电、压敏及电热性能研究

发布时间：2018-01-06 23:24

本文关键词：多尺度碳基水泥复合材料的导电、压敏及电热性能研究　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：水泥基材料添加导电相，可显著改善其导电性能，并可使材料具备诸如：压敏、电热、电磁屏蔽等多功能。本文采用碳纤维、碳黑、碳纳米管三种多尺度碳基材料作为导电相，制备混掺碳基导电水泥复合材料，围绕着复合材料的导电性能、压敏性能以及电热性能方面展开系统研究。主要内容如下：研究了多尺度碳基水泥复合材料的导电性能。通过单掺碳纤维、碳黑、碳纳米管水泥复合材料的导电渗流曲线确定各自的渗滤区间，以此为基础进行三者混掺配比优化，制备了不同电阻率范围的混掺试件，并得到了具有优异导电性能的混掺配方。进而结合SEM微观分析和EDX分析，探讨了三种多尺度碳基材料的导电网络结构形成的机制。研究结果表明：三者混掺时水泥复合材料的电阻率均显著小于它们各自单掺时的电阻率，导电性能改善明显；三种碳基材料的多尺度效应，使得水泥基体内形成了丰富完善的导电网络结构。研究了多尺度碳基水泥复合材料的压敏性能。通过单调加载和循环加载，对七种不同混掺配比试件的压敏性能进行了试验，进而选取一种压敏性能较好的试件，探讨了两个主要环境因素—温度和湿度对其压敏性能的影响，并进一步研究了加载频率对压敏效应的影响。研究结果表明：F02T15B1和F03T15B2混掺配比试件的压敏性能表现较好，，F02T15B1电阻变化率达到9.5%，灵敏系数在42左右；随着温度的升高，电阻变化率先逐渐增大再减小；随着湿度的增大，电阻变化率逐渐减小；电阻变化率随加载频率的增大而逐渐减小，且其传感性能也在逐渐丧失，复合材料所能感知的最大加载频率为0.5Hz。研究了多尺度碳基水泥复合材料的电热性能。采用热电偶测试了各试件在室温下电致热过程的升温曲线，进而在低温环境下，借助红外摄像机，实际测试了试件的化冰性能。研究结果表明：各试件在室温20V下通电30分钟，均有较大幅度温升，试件发热性能良好，电压增大为30V，试件发热性能增强；低温与室温相比，相同电压下，各试件温升均大幅度降低；试件F03T15B3化冰显著，低温20V下，化冰效率为863J/g，电能有效利用率约为41.4%，电压加大至30V，化冰量显著增加，化冰效率提升27.2%，电能有效利用率提高了15.4%，可见电压的提高能够显著提升碳基水泥复合材料的化冰效率。
[Abstract]:Adding conductive phase to cement-based materials can significantly improve its electrical conductivity and make the materials have many functions such as pressure-sensitive, electrothermal, electromagnetic shielding and so on. Carbon fiber and carbon black are used in this paper. Carbon nanotubes (CNTs) three kinds of multi-scale carbon-based materials are used as conductive phase to prepare carbon-doped conductive cement composites. The main contents of this paper are as follows: (1) A systematic study on varistor and electrothermal performance is carried out. The conductivity of multi-scale carbon matrix cement composites was studied. The percolation curves of carbon fiber carbon black and carbon nanotube cement composites were used to determine their percolation intervals. On the basis of this, we optimize the blending ratio of the three components, and prepare the different resistivity range of the mixed samples, and get the blending formula with excellent conductivity. Then, combined with the SEM microanalysis and EDX analysis. The formation mechanism of conductive network structure of three kinds of multi-scale carbon based materials is discussed. The results show that the resistivity of cement composites when mixed with each other is significantly lower than that of their single doped composites. The electrical conductivity was improved obviously. The multi-scale effect of three carbon-based materials results in the formation of rich and perfect conductive network structure in cement-based materials. The pressure-sensitive properties of multi-scale carbon matrix cement composites were studied. The pressure sensitivity properties of seven kinds of specimens with different mixing ratios were tested by monotone loading and cyclic loading. Then, two main environmental factors, temperature and humidity, were selected to study the effect of temperature and humidity on the pressure sensitivity. The effect of loading frequency on the varistor effect is further studied. The results show that the varistor properties of the specimens mixed with F02T15B1 and F03T15B2 are better. The change rate of F02T15B1 resistance is 9.5 and the sensitivity coefficient is about 42. With the increase of temperature, the change of resistance increases gradually and then decreases. With the increase of humidity, the change rate of resistance decreases gradually. The resistance change rate decreases gradually with the increase of loading frequency and its sensing performance is gradually lost. The maximum loading frequency of the composite is 0.5 Hz. The electrothermal properties of multi-scale carbon based cement composites were studied. The heating curves of the electrothermal process of each specimen at room temperature were measured by thermocouple, and then the infrared camera was used in the low temperature environment. The experimental results show that each specimen has a large temperature rise at room temperature 20 V for 30 minutes, and the heating property of the specimen is good, and the voltage increases to 30 V. The heating property of the specimen is enhanced; Compared with room temperature at low temperature, the temperature rise of each specimen decreases significantly at the same voltage. At 20 V low temperature, the ice reduction efficiency is 863 J / g, the effective utilization ratio of electric energy is about 41.4, the voltage increases to 30 V, and the amount of ice deicing increases significantly. The efficiency of ice removal was increased by 27.2g, and the effective utilization rate of electric energy was increased by 15.4.The increase of visible voltage can significantly improve the efficiency of ice removal of carbon based cement composites.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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