The Tribological Performance of Frictional Pair of Gas–Liquid Miscible Backflow Pumping Seal in Oil–Air Environment

Abstract

The gas–liquid miscible backflow pumping seal (G-LMBPHS) is a non-contact mechanical seal that is suitable for high-speed bearing chambers. However, the tribological properties and wear mechanisms of the frictional pair of G-LMBPHS in an oil–air environment have not yet been comprehensively studied. In this study, the tribological properties of six frictional pairs, consisting of three hard materials (18Cr2Ni4WA, Al2O3 coating, and Cr2O3 coating) and two soft materials (metal-impregnated graphite [Metal-IG] and resin-impregnated graphite [Resin-IG]), were analyzed using a disc-on-disc tribometer. An oil–air environment was created using a minimal quantity lubrication (MQL) system and a closed chamber. The results show that the COF of the four frictional pairs consisting of two coatings and two graphites decreases gradually with increasing rotational speed, and the frictional pairs composed of Al2O3 coating and Resin-IG and Cr2O3 coating and Resin-IG have the lowest COF between 0.022 and 0.03. Therefore, the frictional pairs of G-LMBPHS are in a mixed lubrication condition. The lubricant in the oil–air environment is adsorbed and stored in pits on the surface of graphite and coatings, enhancing the hydrodynamic effect of the spiral grooves and reducing the COF by up to 45%. Metal-IG has better wear resistance than Resin-IG, and the frictional pair consisting of Cr2O3 coating and Metal-IG has the lightest wear. This study provides an important basis for the selection of G-LMBPHS frictional pairs in oil–air environments.

Study on the Evolution of Sealing Performance during the Start-Up Process of Dynamic Pressure Seals Based on Three-Dimensional Fractal Functions

“…These studies have established a theoretical foundation for analyzing the static sealing performance of dynamic pressure seals. Li [6] and Bai [16] found that the dynamic leakage rate of the dynamic seal increased significantly compared to the static leakage rate through experimental study. This indicates the importance of analyzing the evolution of sealing performance during the start-up process of the dynamic pressure seal.…”

“…This transition leads to an increase in seal leakage and a decrease in the sealing performance if there is improper design or significant machining errors. In severe cases, static leakage may occur, significantly impacting the seal's operational lifespan [4][5][6]. Therefore, the study of the performance of the dynamic pressure seal start-up process is very important.…”