各向异性硅橡胶-铁粉复合材料力学性能及压阻性能研究材料学专业论文.docxVIP

内 内蒙古科技大学硕士学位论文 I I 摘 要 本文以羰基铁粉为导电填料、GMX6117 硅橡胶为基体，制备了硅橡胶导电复合材 料，对复合材料的力学和导电性能进行检测和分析。本文的特点在于，通过外加磁场控 制导电铁粉在基体的排列和分布，控制复合材料的宏观性能及其对环境温度/应力的敏感 性，探索其作为新型柔性应力、温度传感器的潜力。 在液体硅橡胶硫化过程中施加磁场，铁粉在磁场作用下迁移，获得了定向排列的纤 维状组织。在交变磁场中，铁粉磁化方向不断变化，在定向排列时容易取向、填补组织 空白，故交变磁场获得排列组织明显优于直流稳恒磁场。 拉伸力学试验显示，硅橡胶复合材料的拉力-位移曲线接近线性，没有明显的屈服 点，拉伸强度、断裂伸长率较大；定向排列的复合材料的纵向抗拉强度和断裂伸长率均 高于铁粉随机分布的复合材料，交流磁场的作用优于直流磁场，因为后者得的定向排列 组织的完整性、连贯性优于前者；试样抗拉强度和弹性模量的各向异性，测试显示组织 定向排列方向的力学性能高于垂直方向，而且都明显高于颗粒随机分布的复合材料。 电性能检测试验显示，随机复合材料的渗流阈值为20wt%，排列复合材料的渗流阈 值约为5wt%。复合材料的电阻-填料曲线渗流转变的标度因子t=1.6～2，复合经典渗流理 论，施加磁化后，定向排列渗流网络的相干长度增大，故使t增大；复合材料的电阻随外 加压力增加而下降，即出现负压阻系数，在P=0.05～0.1Mpa之前，电阻曲线非线性下 降，之后电阻曲线趋于稳定。对压阻曲线的数据拟合显示，电阻随压力的变化规律可以 用Ruschau模型解释，说明复合体系电阻的微观模型符合Simmons量子隧道理论；本体系 压阻性能比较稳定，随着循环加压次数的增加，复合材料电阻变化幅度较小，经交变磁 场处理的试样，其100次循环电阻变化5%。 关键词：硅橡胶；羰基铁粉；磁场排列；力学性能；压阻性能 II II Abstract In this paper, silicon rubber (SR) filled with micro-carbonyl iron powder composites (SR-Fe) was prepared, SEM/EDS, XRD techniques were used to characterize the microstructure and phase of composites, the mechanical properties and piezoresistivity were measured and analyzed, and the concerned mechanisms were probed. The following inclusions were derived: Imposing external magnetic field during the vulcanizing of liquid silicon rubber usher will induce directed microstructures consisting of aligned iron powders in silicon rubber. In the alternating magnetic field, magnetization direction alters at a specific frequency, so iron particles are easier to fill the vacancy and get rise to more perfect directed microstructures. Tensile tests on SR composite samples show the strain depends linearly on the displacement, observes as in typical rubbers, there is none of yield in tensile curves. The tensile properties, such as tensile strength and breaking elongation, of aligned directed composites exhibit clearly anisotropic in aligned (longitudinal) and perpendicular directions and the values in both directions are found higher than those obtained in random composites. Moreo