Lv Yuzhen

Effect of Ageing on Insulating Property of Mineral Oil-based TiO 2 Nanofluids

A class of mineral oil-based nanofluid has been developed by modifying mineral oil with TiO2 nanoparticle to enhance their dielectric performance. In this paper, we present the investigation results of aged nanofluids, which have been subjected to accelerated aging condition of 130°C for 6 days. Both AC breakdown voltage and PDIV tests were carried out according to ASTM standards respectively. It was found that AC breakdown voltage of nanofluids has been largely improved before and after aging 6 days. The mean value of PDIV in aged nanofluid achieves an increase of 1.16 times than that of mineral oil. In addition, the results of statistical data indicate that 1% probability breakdown voltage of nanofluid is 78.34kV, which is 8kV higher than that of mineral oil. The experimental results demonstrated that both breakdown voltage and PDIV of mineral oil can be significantly improved by modifying with TiO2 nanoparticles.

油酸修饰TiO 2 纳米棒的溶剂热合成及形貌调控研究

采用溶剂热法在两种不同反应体系中制备TiO 2 纳米棒, 采用X射线粉末衍射法(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热重分析(TG)对产物的结构、形貌和表面修饰状态进行表征。结果表明, 表面修饰和结晶过程是影响TiO 2 纳米棒形貌的主要因素, 在无水反应体系中, 当钛盐与油酸配比为1︰10时所制TiO 2 纳米棒的长径比可达11.5, 是相同配比水解反应体系产物的2.3倍。这一方面是因为油酸在TiO 2 表面的选择性吸附促使晶粒沿一维方向生长, 增加其用量提高了纳米棒的长径比; 另一方面, 无水体系反应速率较水解体系缓慢, 有利于晶粒的充分生长和纳米棒之间的“定向附着”, 显著增大了纳米棒的长径比。所得最佳长径比TiO 2 纳米棒对变压器油的正冲击击穿强度显示出良好的改性作用。采用溶剂热法在两种不同反应体系中制备TiO 2 纳米棒, 采用X射线粉末衍射法(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热重分析(TG)对产物的结构、形貌和表面修饰状态进行表征。结果表明, 表面修饰和结晶过程是影响TiO 2 纳米棒形貌的主要因素, 在无水反应体系中, 当钛盐与油酸配比为1︰10时所制TiO 2 纳米棒的长径比可达11.5, 是相同配比水解反应体系产物的2.3倍。这一方面是因为油酸在TiO 2 表面的选择性吸附促使晶粒沿一维方向生长, 增加其用量提高了纳米棒的长径比; 另一方面, 无水体系反应速率较水解体系缓慢, 有利于晶粒的充分生长和纳米棒之间的“定向附着”, 显著增大了纳米棒的长径比。所得最佳长径比TiO 2 纳米棒对变压器油的正冲击击穿强度显示出良好的改性作用。

Solvothermal Synthesis and Morphological Control of TiO

采用溶剂热法在两种不同反应体系中制备TiO 2 纳米棒, 采用X射线粉末衍射法(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热重分析(TG)对产物的结构、形貌和表面修饰状态进行表征。结果表明, 表面修饰和结晶过程是影响TiO 2 纳米棒形貌的主要因素, 在无水反应体系中, 当钛盐与油酸配比为1︰10时所制TiO 2 纳米棒的长径比可达11.5, 是相同配比水解反应体系产物的2.3倍。这一方面是因为油酸在TiO 2 表面的选择性吸附促使晶粒沿一维方向生长, 增加其用量提高了纳米棒的长径比; 另一方面, 无水体系反应速率较水解体系缓慢, 有利于晶粒的充分生长和纳米棒之间的“定向附着”, 显著增大了纳米棒的长径比。所得最佳长径比TiO 2 纳米棒对变压器油的正冲击击穿强度显示出良好的改性作用。采用溶剂热法在两种不同反应体系中制备TiO 2 纳米棒, 采用X射线粉末衍射法(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热重分析(TG)对产物的结构、形貌和表面修饰状态进行表征。结果表明, 表面修饰和结晶过程是影响TiO 2 纳米棒形貌的主要因素, 在无水反应体系中, 当钛盐与油酸配比为1︰10时所制TiO 2 纳米棒的长径比可达11.5, 是相同配比水解反应体系产物的2.3倍。这一方面是因为油酸在TiO 2 表面的选择性吸附促使晶粒沿一维方向生长, 增加其用量提高了纳米棒的长径比; 另一方面, 无水体系反应速率较水解体系缓慢, 有利于晶粒的充分生长和纳米棒之间的“定向附着”, 显著增大了纳米棒的长径比。所得最佳长径比TiO 2 纳米棒对变压器油的正冲击击穿强度显示出良好的改性作用。

lt;inf

Copper sulfide deposition on oil-paper insulation will lead to insulation deteriorations or failures in power transformers. Recently, nanoparticles have exhibited great potential in improving dielectric strength of transformer oil. In this work, we aim to investigate the effect of semiconductive nanoparticle on the sulfur corrosion behaviors in the oil-paper insulation by adding certain amount of active organic sulfide. Thermal aging tests of paper-wrapped copper strips in both pure mineral oil and nanofluid were carried out. The corrosive characteristics of paper-wrapped copper strips were measured by scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) analysis. The AC breakdown and lightning impulse breakdown voltages of two corroded oil samples were also tested. Experiments and analysis results indicate that the copper sulfide deposition not only changes the surface morphology of copper strips and insulation paper, but also reduce the dielectric strength of transformer oil. It was found that semiconductive nanoparticles can improve the partial discharge-resistance of corroded transformer oil. The obtained results are helpful for further understand the sulfur corrosion behavior in oil-paper insulation of power transformers.

gt;2

It recently has shown that nanoparticles can improve the electric properties of transformer oil when it is added in the oil. This paper investigated the effects of nanoparticles on oil impregnated pressboard in terms of the surface discharge development, the surface tracking marks, and the material trapping properties. It is found that the nanoparticles can increase the shallow trap density in the oil impregnated pressboard, resulting in less carbonized tracking marks on the pressboard surface.