- 學位論文
超音波霧化技術於磁性奈米流體磁性質之研究
Study on the magnetic properties of magnetic nanofluids prepared by ultrasonic atomization.
摘要
本論文完成磁性奈米流體之製備與其材料性質之分析。主要目的在探討超音波霧化技術對磁性奈米流體磁性質之影響。首先，將超音波霧化技術應用於化學共沉法，透過改變壓電式超音波微孔霧化片的振盪頻率及霧化液滴鐵離子濃度以製備磁性奈米粒子。接著，透過溶膠凝膠法將穩定劑包覆於奈米粒子製備出穩定的水基磁性奈米流體。進一步，透過同軸套管密度計以推算奈米流體之粒子殘存率，最後，透過加速樣品測磁儀量測和分析磁性奈米流體磁性質。 研究結果發現，粒子殘存率隨著霧化片振盪頻率及霧化液滴鐵離子濃度增加而增加，至一較高值後可能稍稍下降。研究結果亦發現磁相粒子平均粒徑可能增大或減小，但流體飽和磁化場強度及初始磁化率皆隨著霧化片振盪頻率及霧化液滴鐵離子濃度增加呈單調增加。
並列摘要
This thesis presents a study on the preparation of magnetic nanofluids and the analysis of their material properties. The main purpose is to study the influence of ultrasonic atomization technique on the magnetic properties of magnetic nanofluids. First, the ultrasonic atomization technology is applied to the chemical co-precipitation method. The magnetic nanoparticles are synthesized by adjusting the oscillation frequency of piezoelectric ultrasonic microporous atomizer plate and the concentration of iron ions of atomized droplet. Then, the sol-gel method is used for covering a stabilizer layer on each particle, so as to prepare stable water-based magnetic nanofluids. Furthermore, by using the co-axial-tube density meter, the residual ratio of particles in fluids is determined. Finally, through the accelerating sample magnetometer, the magnetic properties of magnetic nanofluids are measured and analyzed. It is found that the residual ratio of particles increases with the increase of the oscillation frequency of atomizer plate and the concentration of iron ions of atomized droplet and to greater values and then may decrease slightly. It is also found that the average magnetic-phase particle diameter may increase or decrease but the saturation magnetization and initial magnetic susceptibility of fluid monotonically increase with increasing oscillation frequency of the atomizer plate and the concentration of iron ions of atomized droplet.