# Effect of Hydrophobic Silica Nanochannel Structure on the Running Speed of a Colloidal Damper
###### Abstract  
A colloidal damper (CD) can dissipate a significant amount of vibrations and impact energy owing to the interface power that is generated when it is used. It is of great practical significance to study the influence of the nanochannel structure of hydrophobic silica gel in the CD damping medium on the running speed of the CD. The fractal theory was applied to observe the characteristics of the micropore structure of the hydrophobic silica gel by scanning electron microscopy (SEM), the primary particles were selected to carry out fractal analysis, and the two-dimensional fractal dimension of the pore area and the tortuous fractal dimension of the hydrophobic silica gel pore structure were calculated. The fractal percolation model of water in hydrophobic silica nanochannels based on the slip theory could thus be obtained. This model revealed the relationship between the micropore structure parameters of the silica gel and the running speed of the CD. The CD running speed increases with the addition of grafted molecules and the reduction in pore size of the silica gel particles. Continuous loading velocity testing of the CD loaded with hydrophobic silica gels with different pore structures was conducted. By comparing the experimental results with the calculation results of the fractal percolation model, it was determined that the fractal percolation model can better characterize the change trend of the CD running velocity for the first loading, but the fractal dimension was changed from the second loading, caused by the small amount of water retained in the nanochannel, leading to the failure of fractal characterization. colloidal damper (CD); hydrophobic silica gel; nanochannel; fractal percolation model; fractal dimension +
Footnote †: journal: Applied Sciences  
**Citation**: [PERSON]; [PERSON] Effect of Hydrophobic Silica Nanochannel Structure on the Hydrophobic Silica Nanochannel Structure on the Hydrophobic Silica Nanochannel Structure on the Hydrophobic Silica  
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mechanism, usually involving experimental studies. Researchers have mainly performed pressurization experiments on hydrophobic silica gels with different modification degrees and pore sizes, allowing the \"hysteresis curves\" of CDs under different conditions to then be obtained. Additionally, the influencing factors of the energy dissipation capacity of CDs can be explored in this process [4; 5; 6]. [PERSON] et al. [7] studied the effect of different vibration frequencies (0\(\sim\)30 Hz) on the energy dissipation efficiency of CDs by dynamic pressure experiments. The results showed that the CDs had different hysteretic curves under different external vibration frequencies. [PERSON] et al. [8] established three vehicle suspension system models including CDs and found that the damping characteristics of the CDs varied with the excitation frequency. [PERSON] et al. [9; 10] considered the flow of water in the silica gel nanochannels of CDs as macro-flow and analyzed the seepage through Poiseuille theory. It was determined that the complex pore structure of porous silica gel has a great influence on the seepage velocity of water in the channels. The working mechanism of a CD involves colloid and interface science. The core scientific problem is to explore the law of liquid seepage in nanochannels. Owing to the complexity and disorder of the porous medium channel structure, there are a number of limitations for the traditional theories and methods. Since the microstructures of porous silica gel have the fractal characteristics of statistical self-similarity in a certain scale, this provides a new method to apply fractal theory and study the transport properties of silica gel nanochannels. [PERSON] and [PERSON] [11] proposed a fractal seepage model including fractal dimension according to the particle size, porosity, and pore structure of porous media, which was in good agreement with the experimental data.