复合纳米碳化硅包芯线蠕墨铸铁孕育及其效果分析

采用喂线法对蠕墨铸铁进行蠕化及孕育处理,分析了纳米SiC、微米SiC,以及纳米SiC含量(质量分数)为1%、10%、20%的复合纳米SiC孕育线对蠕墨铸铁的孕育效果。试验结果表明:复合纳米SiC孕育剂的孕育效果优于纯纳米SiC和纯微米SiC孕育剂,当加入量为0.05%时,含10%纳米碳化硅的复合纳米碳化硅对蠕墨铸铁的孕育效果最佳。

硅灰制备硅/碳化硅纳米复合材料及其储锂性能研究

硅负极的体积效应导致锂离子电池的循环寿命短且容量迅速衰减,如何提高硅负极材料的循环稳定性至关重要。采用了熔盐辅助镁热还原法,通过使用含有单质碳的工业固体废弃物硅灰,成功设计了一种碳化硅增强的硅纳米材料(SF-Si),所制备的SF-Si样品不仅保留了SF本身存在的SiC,还将单质碳转化为SiC,使样品中的SiC含量达到了16.4%(质量分数)。与经过热处理去除单质碳的硅灰制备的硅材料(H-SF-Si)相比,SF-Si负极材料表现出更好的循环性能和倍率性能,即第1圈2584.76 mAh·g^(-1)的高比容量和第100圈时具有83%的容量保持率,并且在高电流密度5 A·g^(-1)下的平均容量仍为877.28 mAh·g^(-1),这主要归因于更高的SiC含量。研究表明,硅灰在锂离子电池硅负极领域具有应用潜力,其碳元素在制备硅基纳米材料时发挥积极的作用。

纳米碳化硅/硅橡胶复合物介电性研究

制备了质量分数分别为1%、2%、3%、4%、5%、6%和7%的纳米碳化硅/硅橡胶复合物,利用宽频介电谱测试仪测试了不同碳化硅含量的纳米碳化硅/硅橡胶复合物的介电谱特性.结果表明:纳米碳化硅/硅橡胶复合物的介电常数在室温下随碳化硅含量的增加而增加,且在频率小于1Hz时,复合物的介电常数小于纯硅橡胶的介电常数.当频率小于50Hz时,复合物的介质损耗角正切随碳化硅含量的增加而降低,当频率大于1k Hz,复合物的介质损耗角正切随碳化硅含量的增加而增加.同时研究了纳米碳化硅/硅橡胶复合物的击穿特性,通过交流击穿试验可知,纳米碳化硅/硅橡胶复合物的击穿场强随纳米碳化硅含量的增加先增加后降低,当碳化硅质量分数为3%时,击穿场强出现最大值.

纳米碳化硅/硅橡胶复合物非线性电导特性研究

将纳米碳化硅填加到硅橡胶中,可以获得具有非线性电导特性的纳米碳化硅/硅橡胶复合物.本文研究了质量分数分别为5 wt%,15 wt%,30 wt%,45 wt%的纳米碳化硅/硅橡胶复合物的非线性电导特性,建立了电导率与场强的函数关系,分析了复合物的非线性电导机理,并测试了复合物的介电谱特性和击穿特性.为了探讨非线性碳化硅/硅橡胶复合物应用于电缆终端和复合绝缘子以均匀其电场分布的可能性,应用COMSOL Multiphysics软件,对电缆终端和复合绝缘子中的电场分布进行了仿真分析.仿真结果表明,将纳米碳化硅/硅橡胶复合物应用于电缆终端应力锥的绝缘部分,以及应用于复合绝缘子的端部,可以有效地降低其最大场强.

镍基纳米SiC复合镀层的摩擦学性能

为研究镍基纳米 Si C复合镀层的摩擦学性能 ,在A3钢板上制备了该镀层 ,利用扫描电镜对镀层显微组织进行观察 ,通过纳米显微力学探针测量镀层微区硬度 ,在 MM-2 0 0摩擦磨损试验机上对镀层进行磨损试验 ,研究阴极电流密度、温度和镀液中 Si C浓度等主要工艺参数对镀层耐磨性能的影响。结果表明 :Si C颗粒在镀层中分布均匀 ;Si C颗粒附近镀层的硬度是纯镍镀层的 3倍 ,但随着远离 Si C,复合镀层硬度明显下降 ;复合镀层的耐磨性能与普通镍镀层相比有较大幅度的提高 ,在油润滑条件下磨损体积为普通镍镀层的 1/ 8。

PIEZOSPECTROSCOPIC STUDY OF RESIDUAL STRESSES AROUND INDENTATIONS IN SiC/Al_O_3 NANOCOMPOSITE

A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. <

Effect of SiC content on dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites

The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.