Experimental study of surface roughness on improving the tribological performance of sealing pairs in magnetorheological damper

Comprehension of the tribological behavior of magnetorheological fluid (MRF) is crucial in many fields, particularly those related to seal wear. The sealing conditions are more complex than traditional media due to composition and rheological characteristics of MRF. The sealing pairs are prone to wear failure when in contact with magnetic particles. To this end, the paper focuses on the influence of surface roughness on MRF tribological properties with and without magnetic field. The whole experiment is carried out by a self-developed device to reproduce the wear evolution between the sealing pairs for magnetorheological damper. Experimental results show that higher surface roughness exhibits lower friction coefficient and better friction performance under MRF, especially in the absence of magnetic field. This is in stark contrast to the best wear resistance exhibited by polished samples under methyl silicone oil, a carrier fluid of MRF. This means that the effective coupling between surface roughness and iron particles helps to improve the friction and wear performance of sealing pairs. On this basis, the optimum surface roughness values of metal pin under MRF are obtained. Subsequently, the effect of pin surface morphology on the dynamics of iron particles are confirmed through the analysis of scanning electron microscopy images. It is further demonstrated that wear mechanism varies with surface roughness, that is, as the roughness increases, from sliding to mixing, and finally to rolling. Consequently, this research is of great significance for improving the wear resistance of sealing pairs under MRF.