Nano-sized silicon carbide/mullite bi-layered film was applied onto the surface of graphite using electrophoretic deposition (EPD) method from stabilized suspensions. The suspensions were prepared adding 5 g L⁻¹ SiC and 10 g L⁻¹ mullite in ethanol. The effects of adding various amounts of polyethylene imine (PEI) on the stability of suspensions were investigated by visual inspection (sedimentation height), measuring the zeta potential, and particle size distribution. As a result, the addition of 6.0 dwb% and 1.5 dwb% PEI to SiC and mullite suspensions were found to be an effective way in dispersing of nanoparticles. The zeta potential values of well-stabilized suspensions were determined 37.6 mV and 42.4 mV for SiC and mullite suspensions, respectively. Therefore, the coating processes were conducted with the optimal amounts of PEI. In the deposition process, the optimal distance between electrodes was determined 10 mm. In order to investigate the coating process parameters, the optical microscopy (OM) was used for single-layer coatings. The results reveal that applied voltages of 40 V and 10 V with deposition periods of 50 s and 60 s bring about uniform coatings. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were carried out to evaluate the microstructure. The thicknesses of green coatings were measured about 24.15 μm for SiC layer and 7.23 μm for the mullite layer.

中文翻译：

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从稳定的悬浮液中电泳沉积纳米级碳化硅/莫来石双层涂层

使用电泳沉积（EPD）方法从稳定的悬浮液中将纳米尺寸的碳化硅/莫来石双层薄膜涂到石墨表面上。通过添加5 g L ^-1 SiC和10 g L ^-1制备悬浮液莫来石在乙醇中。通过目视检查（沉降高度），测量zeta电位和粒径分布，研究了添加各种量的聚乙烯亚胺（PEI）对悬浮液稳定性的影响。结果，发现向SiC和莫来石悬浮液中添加6.0dwb％和1.5dwb％的PEI是分散纳米颗粒的有效方法。SiC和莫来石悬浮液的稳定稳定悬浮液的Zeta电位值分别确定为37.6 mV和42.4 mV。因此，涂覆过程以最佳的PEI量进行。在沉积过程中，电极之间的最佳距离确定为10 mm。为了研究涂层工艺参数，光学显微镜（OM）用于单层涂层。结果表明，在沉积时间分别为50 s和60 s的情况下施加40 V和10 V的电压可获得均匀的涂层。另外，进行了扫描电子显微镜（SEM）和原子力显微镜（AFM）以评价其微观结构。SiC层的生坯涂层厚度约为24.15μm，莫来石层的生坯涂层厚度约为7.23μm。