A Novel Sealing Method Using Nano-Micro Magnetic Powders and Its Leakage Rate Analysis

Fe
₃
O
₄
nanoparticles have been a research focus area for many years and have been applied in fields like medical treatment, catalysis and sensors. Particularly, they can be coated and dispersed in a solvent to prepare magnetic fluids. Magnetic fluid sealing is a high-performance sealing method, but it is still not capable to work in extreme conditions such as elevated temperatures. Here we present a new sealing method with nano-micro magnetic powders as the sealing medium. Fe
₃
O
₄
particles with average sizes of 20 nm, 200 nm, and 25
$\mu \text{m}$
are prepared by the chemical co-precipitation method. The fluid permeability of magnetic powders is estimated by Darcy’s law. Finally, a static sealing prototype is designed and optimized based on magnetic field distribution analysis. Sealing experiments show a strong relevance between particle sizes and leakage rate. The mixture of nano and micrometer-sized Fe
₃
O
₄
particles leads to a significant decrease in leakage rate, making magnetic powder sealing a promising novel sealing method.